So how bad is -1 diopters? -2? -10? My eyechart research! https://bwelcometothevisionandeyeforums.runboard.com/t211 Runboard| So how bad is -1 diopters? -2? -10? My eyechart research! en-us Thu, 28 Mar 2024 14:52:32 +0000 Thu, 28 Mar 2024 14:52:32 +0000 https://www.runboard.com/ rssfeeds_managingeditor@runboard.com (Runboard.com RSS feeds managing editor) rssfeeds_webmaster@runboard.com (Runboard.com RSS feeds webmaster) akBBS 60 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p963,from=rss#post963https://bwelcometothevisionandeyeforums.runboard.com/p963,from=rss#post963The below is someone's experience with Intacs(but anything that undercorrects will achieve the same end result be it glasses, lasik, orthoK, intacs) Hi Molly, First of all, a 'plano', or zero refraction is not required to have 20/20 or better vision. For example, I am about -0.50 in my left eye, and see 20/15 with it. My comments: Such a small residual myopia undercorrection does not have much affect on UCVA. No one with a -.25 undercorrection will lose a line and this is comming from an optometrist's experience. -.5 diopters typically costs just one line so instead of 20/15 you may be 20/20 which is still considered perfect vision and nothing should be done but enjoy your crisp vision! I have tested my UCVA with my older glasses and found almost no difference with a slight undercorrection. But a slight undercorrection can help keep you out of readers without really making an impact on distance vision so its great! For this reason, an undercorrection with orthoK will pratically eliminate my dependency on glasses, period except maybe for driving.nondisclosed_email@example.com (Myope5)Wed, 25 Oct 2006 00:27:11 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p775,from=rss#post775https://bwelcometothevisionandeyeforums.runboard.com/p775,from=rss#post775I heard somewhere the following value: -.5 = 20/25 -1 = 20/50 -1.5 = 20/80 -2 = 20/120 -2.5 = 20/200 -3 = 20/300 -4 = 20/500 -5 = 20/800 -6 = 20/1200 -7 = 20/1800 -8 = 20/2700 -9 = 20/4000 My comments They believe each additional diopter results in 1.5x worse UCVA for the moderate and especially higher prescriptions. Elsewhere, I heard this: -1 = 20/40 -2 = 20/100 -3 = 20/200 -4 = 20/400 -5 = 20/600 -6 = 20/900 -7 = 20/1200 -8 = 20/1600 -9 = worse than 20/2000 My comments The closest in agreement to my objective blur chart and may in fact reflect the average values of UCVA for most myopes. I often use that chart for rounding and also to reflect more average UCVA rather than maximum values. A third source said: -1 = 20/50 -2 = 20/150 -3 = 20/300 -4 = 20/600 -5 = 20/1000 -6 = 20/1600 -7 = 20/2400 My comments Quite conservative, more so on the higher prescriptions One lasik site said that: -1.00 = 20/60 -2.00 = 20/200 -3.00 = 20/400 -4.00 = 20/800 -5.00 = 20/1,200 -6.00 = 20/2,000 My comments I already commented on this a few posts ago. Ill say again they are very conservative/strict, especially on the higher prescriptions. My own objective blur chart: -.5 = 20/25 -1 = 20/40 -1.5 = 20/60 -2 = 20/100 -2.5 = 20/150 -3 = 20/200 -4 = 20/300 -5 = 20/500 -6 = 20/700 -7 = 20/1000 -8 = worse than 20/1200 My comments This is my own rounded to snellen eyechart verson of the objective blur chart. -6 is actually 20/727 so the rounding to the nearest hundred is about 4% off which isnt all that much. There isnt a 20/700 on the snellen, but I put that number there for accuracy as it falls between 20/600 and 20/800. I did round off by 10% for -4, but in reality most -4's will probably not be able to see 20/300 snellen. Overall, let me group the values together to make it easier to compare. -1 values: 50, 40, 50, 60, 40 -2 values: 120, 100, 150, 200, 100 -3 values: 300, 200, 300, 400, 200 -4 values: 500, 400, 600, 800, 300 -5 values: 800, 600, 1000, 1200, 500 -6 values: 1200, 900, 1600, 2000, 700 -7 values: 1800, 1200, 2400, >2000, 1000 -8 values: 2700, 1600, >2400, >>2000, >1200 I am assuming they are taking 20/20 BCVA into factor. It appears the average for -1 is 20/50 with many capable of 20/40. It is clear(pun intended) that -1 does not result in much blur. For -2, we see(another pun) that the range is 20/100 to 20/200 with the average in between at 20/150. I have checked lots of websites and studies and nearly all of them have their own idea, that being 20/100 or 20/200 usually, some say 20/100 to 20/200, others say between 20/100 and 20/200. For -3, it appears to be twice as bad as -2 accroding to most sources. Some sources put -3 at a little more than twice as bad. By -4, I commonly see 20/400 associated with that amount of myopia. Ive seen several optometrists also say this. At -5, you most likley wont see 20/400 and be off the charts at most snellen charts. Going by the averages I listed, -5 appears quite bad, being between 20/600 and 20/800! -6 and up is high myopia and worse than 20/800 by those averages! Summary of averages: -1 = 20/50 -2 = 20/150 -3 = 20/300 -4 = 20/500 -5 = 20/800 -6 = worse than 20/800nondisclosed_email@example.com (Myope5)Sun, 13 Aug 2006 05:58:11 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p774,from=rss#post774https://bwelcometothevisionandeyeforums.runboard.com/p774,from=rss#post774The UCVA was 20/60 and manifest refraction was -1.75 D + 0.75 D at 55 producing 20/30. My comments: spherical equivalent of -1.25 would decrease 20/30 into 20/75 so she must have good blur preception and/or squinted. Update on my vision self-treatment experiment: I had my annual medical exam today (for the local Sheriff's Office where I work, not for the FAA), and today's vision test results were as follows: Refractive Error (Manifest): OS: –4.50 sph –0.50 cyl OD: –3.75 sph –0.25 cyl Distant Visual Acuity: OS: 20/200 (uncorrected), 20/10 (corrected) OD: 20/100 (uncorrected), 20/10 (corrected) OU: 20/70 (uncorrected), 20/10 (corrected) My comments: Impossible unless he squinted or had the eye test in bright light. 20/10 BCVA is unusual(less than 2%) and gets a 1 diopter bonus. That still comes out to 20/170 and 20/300! I simulated -3.75 and I can barely see 20/400 in a fair test. Most people arent gonna see better than 20/300 with -3.75 An estimated 20 million adult Americans have mild nearsightedness (roughly speaking, 20/80 to 20/300 vision), which is the treatment range for Intacs. This range includes people requiring from -1.0 to -3.0 diopters of myopic correction. Intacs are designed especially for this group -- the largest segment of nearsighted adults in the U.S. My comments: Sorry but -1 is much better than 20/80. -3 and 20/200 sounds right. [0012] If the retainer lens is discontinued for more than 12-24 hours, significant regression occurs in the corneal topography. For example, if the baseline myopia was -3 diopters (D), and the unaided visual acuity was 20/300, and after treatment, myopia was corrected to -0.50D and 20/20 WVA, if the retainer is worn each night or day, a 20/20-20/30 WVA, and less than -1 D myopia, can be maintained. If the patient does not wear the retainer lens for a minimum of 2 days and 2 nights, the UVA may regress to 20/100 -20/200, and the myopia may regress up to -2 D to 3 D. My comments: OrthoK talk and how much it improves vision. -3 is quite bad being at 20/200 to 20/300 per the article. Revisit of diopters to 20/x in my subjective testing, how well I see with the following prescriptions using various undercorrections with different minus powers. I tested mostly my dormant left eye which has 20/25 BCVA. The right eye with its 20/30 BCVA needs -.25 diopters less myopia to see the same line. Left eye: plano(needs -5 correction) 20/25 -.5 undercorrection 20/30 -.75 undercorrection 20/40 -1 undercorrection 20/50 -1.25 undercorrection 20/60 -1.5 undercorrection 20/80 -1.75 undercorrection 20/100 -2 undercorrection 20/120 -2.25 undercorrection 20/150 -2.5 undercorrection 20/200 -3 undercorrection 20/250 -3.25 undercorrection 20/300 -3.75 undercorrection 20/400 -4.75 undercorrection 20/600 -5(no correction) slightly below 20/600 The first half diopter blurs very little, only one line. The first diopter reduces my vision in half. It gets worse expotentionally from there. At -2 undercorrection, I definately cant see 20/100, the 20/200 is pretty easy to see still. At -2.5 the 20/200 is very blurry. The 20/300 is quite blurry and hard to see even at only -3. I cant quite make out 20/400 at -4 but at -3.5 to -3.75 I can but its very blurry. Its gradual where a quarter diopter makes only a tiny difference once I get to -3 and I have to decide how blurry is "too" blurry to actually "see" it and not just recall from memory. At -2.25, -3, -3.5 and -4.5 is where id say I would feel confident passing 20/200, 20/300, 20/400 and 20/600 every time. Ill keep up to date with more testing. -2.25 for 20/200 -3 for 20/300 -3.5 for 20/400 -4.5 for 20/600 To further comment, my diopter charts and their corresponding 20/x are regarded as maximum values one can still just barely make out something. -4.5 has an objective blur of slightly worse than 20/400 so youd need a BCVA of marginally better than 20/20 to just barely discern 20/400. I did put down -4.5 and 20/400 in my rounded verson of the snellen as its closer than -4.25 and 20/375. -4.25 is slightly better than 20/400, -4.5 slightly worse with a 20/20 BCVA. Even though -4.5 is regarded as 20/400, this does not guarantee youll be able to discern 20/400. If not, youll of course be just slightly worse than 20/400. There is no such line as 20/450. You may be able to discern 20/400 with a -.25 lens that takes you down to -4.25 I can sometimes just barely discern 20/400 with a -4 undercorrection in the left eye but usually I need -3.75 and on bad days, -3.5! For someone with a 20/20 BCVA, he will be able to see 20/400 with -.5 diopters more myopia than me. Someone at 20/15 will be able to with -1 more myopia than me! nondisclosed_email@example.com (Myope5)Sat, 05 Aug 2006 03:24:28 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p773,from=rss#post773https://bwelcometothevisionandeyeforums.runboard.com/p773,from=rss#post773Method of predicting visual acuity with change of spherocylindrical refractive error Very interesting website that attempts to convert diopters to uncorrected visual acuity. You can see that with 6mm or larger pupils, the pinhole effect is greatly reduced. This is why eye exams should be done in a darkened room as ive mentioned before. They came up with about 20/30 at -.5 which I disagree. Likewise for 20/50s for -1. The -2 results is pretty close and may be correct for some. Ditto with -3 although I believe -3 is easily twice as bad as -2. Their measure of -4 concides with mine at 20/334 but the gap between -3 and -4 is more than 1.5x, its about 1.7x and some say even 2x! They start to get too generous at -5 and following the pattern. They are too conservative for low diopters. -4 is where they are most accurate. this guy below found it in a lasik book. I calculated it based on subjective blur, but will update it to reflect my objective blur in the second set of paranthesis I just happened to be reading a book this morning, and came across a table listing the relationship between refraction and acuity. (The book is called The Laser Vision Breakthrough, and it said the table should only be considered a rough guide. BTW - you'll learn alot about refractive eye surgeries from the book, although my feeling is that it emphasizes the positive aspects and sugar-coats the potential negatives) The number to the left of the = sign is the spherical measurement. No or minimal refractive error     0.0 = 20/20(normal BCVA)     -0.50 = 20/30(20/25)(20/25) Low myopia     -1.0 = 20/50(20/40)(20/40)     -2.0 = 20/150(20/80)(20/100)     -3.0 = 20/250(20/150)(20/200)     -4.0 = 20/400(20/250)(20/334) Moderate myopia     -5.0 = 20/500(20/400)(20/500)     -6.0 = 20/650(20/500)(20/800)     -7.0 = 20/800(close enough)(20/1000) Extreme myopia     -8.0 = 20/1000(20/800?)(20/1300)     -9.0 = 20/1300(20/1000?)(20/1600) The -5 is the only one they got right. They are too conservative for low myopia and too generous for high myopia. One optometrist even said most figures or calculations tend to be conservative for low amounts, meaning they see better than what we think they do and too generous for high amounts meaning they see worse than the 20/800 or 20/1000 estimate thrown at very high myopes. My Lenses are -2.5 so it will not affect me either way but my uncorrected vision is 20/50 which is pretty good. The funny thing is that I know a chap who's Lenses are -1.0 and -1.25 but his uncorrected vision is 20/100 which is way worse than mine, so it goes to show that the strength of your glasses is no indicator of how well you will see with out them or indeed how good your eyesight is anyway. My comment: That -2.5 guy did not mention BCVA, but if his BCVA is at least 20/10, that explains it to a large extent. He would need to have a BCVA of 20/7 to go in line with my objective blur chart, -2.5 uses the 7x multiplier. Its more likley he has a BCVA of 20/12 to 20/15, is slightly overcorrected and is squinting a little. As for that 20/100 guy, I suspect he has subnormal BCVA, he has cylindar in addition to sphere(for some reason, some people omit or dont mention their cylindar, especially if its low like less than -1) another possibility is he is just not trying at all to interpret blur and only reading down as far as its easy. A normal, healthy eye correctable to 20/20 with -1 sphere, no cylindar should read at least 20/50 if not 20/40. My eyesight was -6 diopters, or worse than 20/200 in both eyes. I could only read the E on the chart, but that's because I memorized it. My comment: Most eyecharts have an "E" on top. Those who "pass" for 20/200 or 20/400 with unusually high prescriptions likley recalled it from memory and not actually "seeing" it which they cant. Someone who is honest and tries to actually see it without squinting or recalling from memory will find they wont be able to see 20/400 if they are much beyond -4. Random generator would be a great way to asset their UCVA by eliminating recall from memory. Thats what they may use for UCVA requirements to be a pilot or in some fields in the army. They even have categories called v1, v2, v3, v4, v5. Technically, I fall into the "moderately myopic" category, since my distance correction is somewhere around a -4 in both eyes. (For those of you playing with decent eyes and who can't translate diopters, -4 in diopters translates to something like 20/400 vision, uncorrected.) My comment: -4 is commonly associated with 20/400, some say worse than 20/400, others say its the limit for 20/400 Within each 1-D range of the spherical equivalent of the refractive error, the visual acuity spanned five to ten Snellen lines. Within the narrow range of refraction between -2.00 and -2.50 D, the mean uncorrected visual acuity was 20/125 for 56 unoperated eyes and 20/63 for 29 operated eyes, a difference of three Snellen lines. My comments: Makes no sense, nonsense. In fact its the courtesty or opposite from what ive seen, not so much in UCVA, but more to do with decreased quality. People after refractive surgury appear to be more picky with residual refractive error. I however agree with the 20/125 at -2 to -2.5 my blur chart shows 20/120 at -2.25 which is in the middle. 20/60 both eyes, just got -1 contacts on a whim the other day (makes reading signs 200 miles away a little easier) only problem is they said they wouldn't do laser eye surgery on me because my vision isn't that bad. My comment: He is lucky his surgeon is competent and has morals not to do lasik on someone that doesnt need it! He does not even need correction except for driving. If we are to assume -1 contacts equals -1.25 glasses, 20/60 sounds close enough Q. What was your eyesight like before LASIK? A. My vision was 20/400, which was enough to cause two of my female friends to clasp their hands and exclaim, "Wow, you're really bad!" My prescription was -3 diopters (nearsighted), or close to that, with some astigmatism. I pretty much wore glasses almost all the time while I was awake. My comment: The astigmatism potion is the real problem because he may not see perfectly clear even from near. Id much rather be alot more myopic and free of astigmatism then at least ill be in focus from near! nondisclosed_email@example.com (Myope5)Sat, 05 Aug 2006 00:55:21 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p772,from=rss#post772https://bwelcometothevisionandeyeforums.runboard.com/p772,from=rss#post772H.R is -1 sphere in left eye and 20/60 This is a fairly poor snellen score for only -1 and he corrects to 20/20! Perhaps he wasnt giving much effort as -1 is generally 20/40. Right Eye 20/1000 20/20 Left Eye 20/1000 20/20   Refraction  Before After Right Eye -6.75 - 0.50 x 165 0.00 - 0.25 x 17 Left Eye -7.25 -1.25 x 004 +0.25 - 0.75 x 61   My comments Looks like an estimate was pulled out. It agrees spot on with my objective blur formula and chart for the right eye, but the left eye would be 20/1200 Right Eye 20/80 20/15 Left Eye 20/70 20/20   Refraction  Before After Right Eye -1.50 -0.50 x 009 -0.25 -0.25 x 166 Left Eye -1.25 -0.50 x 165 -0.25 -0.50 x 50 My comments Should be seeing a little better than this(see my blur multiplier) but is seeing well despite a minor residual prescription post lasik(which he didnt need in my opinion due to such a low script before lasik) Right Eye 20/70 20/20 Left Eye 20/70 20/20   Refraction  Before After Right Eye -1.25 sphere 0.00 Left Eye -1.25 -0.25 x 142 0.00 -0.25 x 17 My comments At her age of 38, she traded up for readers. Should be seeing 20/50 or 20/60 at worst. Right Eye 20/400 20/25 Left Eye 20/300 20/20   Refraction  Before After Right Eye -3.50 -0.50 x159 -0.75 -0.25 x 33 (target: -0.50) Left Eye -2.75 -0.75 x 004 -0.50 (target: -0.75)   My comments Since when did his chart have a 20/300 line? I am gonna assume this to the fact she could see the 20/200 line from 13-14 feet. -3=20/300, -3.75=20/400 and after lasik -.75=20/25, -.5=20/20 So she has a 20/15 BCVA Right Eye 20/800 20/20- Left Eye 20/800 20/20   Refraction  Before After Right Eye -5.25 -0.25 x 03 -0.50 -0.50 x164 Left Eye -4.75 -1.00 x 05 0.00 -0.25 x 005   My comments -5.25 spherical equivalent may be able to see 20/600. I am assuming she stood closer to see the 20/400 E and the surgeon put her down for 20/800.  Before After Right Eye 20/60 20/15 Left Eye 20/60 20/15   Refraction  Before After Right Eye -1.25 – 0.25 x 155 0.00 Left Eye -1.25 – 0.25 x 015 0.00   My comments Should be seeing a little better than that, like 20/40 to 20/50 Right Eye 20/2000 20/30 Left Eye 20/2000 20/20   Refraction  Before After Right Eye -7.00 –2.25 x 175 -0.50 Left Eye -7.00 –2.50 x 002 0.00   My comments spherical equivalent of just over -8 corresponds to 20/1300. She probably count finger(CF) from 2' which corresponds to 20/2000. The fact she can only see 20/30 at -.5 means either she isnt trying or interprets blur poorly. Right Eye 20/3000 20/25 Left Eye 20/3000 20/20   Refraction  Before After Right Eye -9.50–1.75x165 -0.25 Left Eye -10.25–1.75x180 0.00   My comments similar story to the above. Should be about 20/2400. No reason -.25 costs a line, if you check every other testimonal, many people see 20/20 with -.25 to -.5 Right Eye 20/400 20/40 (20/15 After Enhancement) Left Eye 20/400 20/20   Refraction  Before After Right Eye -3.75 – 1.25 x 164 -1.00 sph (0.00 After Enhancement) Left Eye -3.50 – 1.25 x 004 -0.25   My comments Shes a golfer so wanted the best distance vision. She needs readers but doesnt mind. She should still be 20/15 with -.25 and 20/30 at -1 Right Eye 20/800 20/20 Left Eye 20/1000 20/25   Refraction  Before After Right Eye -4.00 sphere 0.00 Left Eye -4.75 sphere -0.25 sphere   My comments another estimate that I disagree with. One lasik website did say -4 is 20/800 which you can see on page 5 of my thread. Right Eye 20/1000 20/20 Left Eye 20/1000 20/20   Refraction  Before After Right Eye -3.25 - 1.50 x 003 0.00 Left Eye -3.50 - 2.00 x 160 - 0.25   My comments -4 and -4.5 spherical equivalent should be 20/400 Right Eye 20/400 20/15 Left Eye 20/4000 20/15   Refraction  Before After Right Eye -3.25 - 1.00 x 003 0.00 Left Eye -3.50 - 0.75 x 175 - 0.25   My comments obvious extra zero typo Right Eye 20/1000 20/15 Left Eye 20/1000 20/15   Refraction  Before After Right Eye -3.25 - 1.00 x 003 0.00 Left Eye -3.50 - 0.75 x 175 - 0.25 My comments Bad estimate. She should be 20/300 or 20/400 Right Eye 20/800 20/15 Left Eye 20/800 20/15   Refraction  Before After Right Eye -4.00 - 0.25 x 097 0.00 Left Eye -3.25 - 0.25 x 115 0.00 My comments Ditto to the above. Right Eye 20/800 20/15 Left Eye 20/600 20/15   Refraction  Before After Right Eye -6.50 -0.75 x 15 0.00 Left Eye -4.75 -0.75 x 11 0.00   My comments Good estimate. Right Eye 20/800 20/20 Left Eye 20/800 20/15   Refraction  Before After Right Eye -2.25 - 0.75 x 079 0.00 Left Eye -2.25 - 0.50 x 73 0.00   My comments geez looks like they didnt even test his UCVA and just put a random snellen number. He might be able to resolve 20/100, if not, definately 20/150! Right Eye 20/800 20/20 Left Eye 20/800 20/15   Refraction  Before After Right Eye -3.50-.50 x 45 0.00 Left Eye -2.50 sph 0.00   My comments Another gee wiz one. Right Eye 20/800 20/15 Left Eye 20/800 20/15   Refraction  Before After Right Eye -3.75 - 0.75 x 008 0.00 Left Eye -3.50 - 0.50 x 75 0.00     My comments try 20/200 Right Eye 20/2000 20/20 Left Eye 20/2000 20/15   Refraction  Before After Right Eye -10.00 -0.50 x 06 +0.50 Left Eye -9.50 -1.00 x156 0.00   My comments my blur chart puts -10 at 20/2000 so this time the doctor got it right. His +.5 overcorrection wont go well with his presbyopia. If he accepts the risks, an enhancement can make his +.5 into -.5 to greatly improve his vision. Right Eye 20/400 20/15 Left Eye 20/400 20/15   Refraction  Before After Right Eye -3.25 - 0.25 x 125 -0.12 Left Eye -4.00 - 0.25 x 28 -0.00   My comments The last one to finish things off. He should be 20/300 in the better eye, but as I said, his eyechart doesnt have that line nondisclosed_email@example.com (Myope5)Sun, 30 Jul 2006 22:30:03 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p771,from=rss#post771https://bwelcometothevisionandeyeforums.runboard.com/p771,from=rss#post771I found another very interesting correlation! Right Eye 20/400 20/15 Left Eye 20/25- N/A (no surgery)   Refraction  Before After Right Eye -2.50 -0.50 x 114 0.00 Left Eye -0.75 -0.50 x 49 same   My comments Her surgeon wisely suggested she leave her good eye well enough alone because it didnt need correction and also to ward off reading glasses. Thats some good BCVA for a -1 spherical equivalent, but she may have had a 20/13 BCVA and -1 would blur to 20/26, hence the 20/25- as theres no 20/26 line and she may have missed one or two on the 20/25 line. I however am supprised why her bad right eye isnt capable of easily seeing 20/200, in fact my math tells me she should be capable of 20/130, making the 20/150 line readable without much difficulty. Right Eye 20/100 20/15 Left Eye 20/100 20/15+   Refraction  Before After Right Eye -2.50 -0.25 x140 0.00 Left Eye -2.25 -0.25 x 15 0.00   My comments 2.5 diopters uses the 7x multi and if his BCVA is 20/15 or a hint better like 20/14.5, this comes out to just over 20/100 so he would see 20/100 but just barely. Right Eye 20/100- 20/15 Left Eye 20/80- 20/15   Refraction  Before After Right Eye -2.25 sph 0.00 Left Eye -2.25 sph 0.00 My comments Very odd, one look and you can see why. Same refraction, same BCVA, different UCVA? I am gonna assume he was squinting a little in one eye or just got tired of straining to read the blurry 20/80 line and didnt try on the other eye. 6x multi makes it 20/90 which falls between 80 and 100, hmmm. update: Found out he has significent aberrations in the right eye and a slight corneal distortion which wavefront lasik fixed. I have a similar problem in my own right eye that makes my BCVA less and I can tell its not perfectly clear. Still I wouldnt risk lasik on myself as my better left eye is dormant and sees fine. Right Eye 20/80 20/15 Left Eye 20/150 20/20   Refraction  Before After Right Eye -2.25 -1.25 x131 0.00 Left Eye -2.75 -1.50 x 28 +0.25 -0.25 x117   My comments -2.75 and -3.5 spherical equivalent. Right eye would be 20/130, left eye would be 20/250. Reason is she squinted. Her picture was shown on the lasik website and shes asian with narrow beady eyes. Right Eye 20/400 20/15 Left Eye 20/400 20/15   Refraction  Before After Right Eye -2.50 -1.25 x141 0.00 Left Eye -2.50 -1.25 x 59 0.00 -0.25 x 37 My comments spherical equivalent of -3 so he should see 20/150 and if not, 20/200 with relative ease. His eyechart had no 20/300 line. Right Eye 20/70 20/20+ Left Eye 20/70 20/15   Refraction  Before After Right Eye -0.25 -2.50 x 11 0.00 Left Eye 0.00 -2.25 x 02 0.00 -0.25 x 88 My comments Heres a rare cylindar script. Take the spherical equivalent and we get -1.25 but I guess the distortions with cylindar can be tricky to interpret when reading a snellen Right Eye 20/200 20/20+ Left Eye 20/400 20/20   Refraction  Before After Right Eye -3.50 -1.25 x 125 0.00 -0.25 x 160 Left Eye -3.25 -0.25 x 54 +0.50 - 0.25 x 60 My comments Looks like the staff who put up his report mistyped "200" instead of "400" for the worse right eye.   Right Eye 20/800 20/25 Left Eye 20/800 20/20   Refraction  Before After Right Eye -4.00 sph -0.25 Left Eye -4.00–0.25x015 0.00   My comments Poor blur preception and making little effort. This is evidenced by the person seeing only 20/25 at -.25 Right Eye 20/400 20/20 Left Eye 20/400 20/20   Refraction  Before After Right Eye -4.25 sph 0.00 Left Eye -4.25 sph 0.00   My comments perfect example Right Eye 20/2000 20/25 Left Eye 20/2000 20/25   Refraction  Before After Right Eye -13.25 - 0.50 x 32 -0.25 - 0.75 x 115 Left Eye -12.25 - 0.50 x 97 -0.75 - 0.75 x 180   My comments Her surgeon just took the 20/2000 figure as an estimate. Funny because he took the same estimate for a -7 and 20/3000 for a -9! She would be 20/3000 at best. I am supprised shes 20/25 in both eyes now even though one has just over -1 spherical equivalent. Maybe she memorized that line with the better eye then recalled it with the worse! Right Eye 20/800 20/25 Left Eye 20/1600 20/20   Refraction  Before After Right Eye -2.00 - 4.00 x 178 - 0.25 - 0.50 x 67 Left Eye -4.75 - 3.75 x 180 +0.37 - 0.75 x 144   My comments -4 and near -7 spherical equivalent. should be 20/400 and 20/1000 or so. I guess all that cylindar makes it hard to interpret blur. Right Eye 20/1000 20/20 Left Eye 20/1000 20/20   Refraction  Before After Right Eye -4.00 - 0.75 x 180 0.00 Left Eye -3.75 -1.50 x 178 -0.25 sph   My comments Um no. Where did this 1000 get pulled from? She should be barely 20/400 accroding to my blur formula. 20/1000 isnt even close. Right Eye 20/800 20/20 Left Eye 20/1000 20/20   Refraction  Before After Right Eye -8.00 - 1.50 x 015 0.00- Left Eye -7.00 - 0.75 x160 +0.25 sph   My comments ill let you figure out whats wrong with this one. Right Eye 20/800 20/20 Left Eye 20/800 20/20   Refraction  Before After Right Eye -6.50 - 0.25 x 10 -0.25 sph Left Eye -4.50 - 0.75 x 11 0.00   My comments Looks like another estimate the doctor pulled when she couldnt see 20/400 in either eye. Her left eye should not be much worse than 20/400 Right Eye 20/800 20/25 Left Eye 20/800 20/20   Refraction  Before After Right Eye -7.75 – 0.25 x 026 -0.25 Left Eye -7.75 sphere (no astigmatiem) 0.00   My comments another estimate. I would place him at 20/1200 based on my formula Right Eye 20/1200 20/15 Left Eye 20/1200 20/20   Refraction  Before After Right Eye -5.00 –0.50 x 157 -0.25 Left Eye -5.25 –0.25 x 122 0.25 –0.50 x 165   My comments isnt that funny her eyes are better than the other 20/800 estimates yet she was put down as 20/1200? I would say she can likley read the 20/600 line if there was one. Shes still 20/15 at -.25 which is proof that a quarter diopter has neglecable blur. Right Eye 20/400 20/20 Left Eye 20/400 20/40   Refraction  Before After Right Eye -2.75 – 1.00 x 100 0.00 Left Eye -2.50 –0.75 x 084 -1.00   My comments Would be pushing it for 20/200, but should be doable in the left. Right eye would definately be 20/300 but his eyechart doesnt have that line. Big gap between 200 and 400. -1 for 20/40 concides with my diopter blur charts. Right Eye 20/800 20/20 Left Eye 20/800 20/20   Refraction  Before After Right Eye -3.50 - 1.50 x 92 0.00 Left Eye -5.00 – 0.50 x 90 -0.25 sph   My comments I estimate 20/400 in the better eye, 20/600 in the worse.nondisclosed_email@example.com (Myope5)Sun, 30 Jul 2006 14:26:47 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p770,from=rss#post770https://bwelcometothevisionandeyeforums.runboard.com/p770,from=rss#post770Right Eye 20/400 20/15 Left Eye 20/400 20/15   Refraction  Before After Right Eye -2.75 -2.00 x 38 0.00 Left Eye -1.50 -2.00 x 131 0.00 -0.25 x 106   My comments He should easily have seen 20/200 in the better eye! Right Eye 20/70 not treated Left Eye 20/70 20/20+   Refraction  Before After Right Eye -0.75 -1.25 x 88 not treated Left Eye -0.75 -0.75 x 85 0.00   My comments spherical equivalent of about -1.25 so she should have been 20/50 or 20/60 at worst. Right Eye 20/200 20/20+ Left Eye 20/200 20/15   Refraction  Before After Right Eye -1.75 -0.50 x 90 0.00 -0.25 x137 Left Eye -1.75 -1.00 x 91 0.00 My comments should read 20/100 without much difficulty based on prescription and 20/15 BCVA. Right Eye 20/150 20/10 Left Eye 20/150 20/15   Refraction  Before After Right Eye -1.75 0.00 Left Eye -2.00 0.00 My comments Should be nowhere near that bad. If hes really capable of 20/10 then -1.75 blurs 4x to 20/40! Right Eye 20/400 20/15 Left Eye 20/400 20/15   Refraction  Before After Right Eye -2.00 -0.50 x168 0.00 Left Eye -2.00 -0.25 x006 0.00 -0.25 x73   My comments Should be way, way better than 20/400. Clearly he wasnt even trying otherwise he would see 20/200 piece of cake and even 20/100 with some effort. All normal healthy eyes correctable to 20/20 or better will easily see 20/200 at -2 and 20/100 with some effort. Right Eye 20/400 20/20+ Left Eye 20/400 20/20   Refraction  Before After Right Eye -4.50 -0.75 x136 +0.25 Left Eye -4.50 -0.50 x101 +0.25 -0.25 106 My comments See what I mean? -4.5 is the limit for 20/400 per my objective blur chart. The guy above at -2 is way better than 20/400. Right Eye 20/200 20/15 Left Eye 20/200 20/15   Refraction  Before After Right Eye -3.25 -1.00 x 167 0.00 Left Eye -3.75 -0.50 x 005 0.00 -0.25 x 70 My comments really pushing it, she may have squinted a little. Id consider her closer to 20/250 to 20/300. Right Eye 20/400 20/15 Left Eye 20/400 20/15   Refraction  Before After Right Eye -3.25 -1.00 x176 0.00 -0.25 x 171 Left Eye -2.50 -1.00 x 29 0.00 My comments Should be 20/300(right eye) and 20/200(left eye) if not somewhat better. Right Eye 20/400 20/20 Left Eye 20/400 20/15   Refraction  Before After Right Eye -3.50 -1.25 x 86 0.00 Left Eye -5.00 -0.75 x 102 -0.25 My comments Left eye has better BCVA so he still sees 20/400 with more myopia. Right Eye 20/200 20/15 Left Eye 20/200 20/20   Refraction  Before After Right Eye -2.50 -0.50 x 111 +0.25 -0.50 x 24 Left Eye -3.50 -0.25 x 115 0.00 - 0.50 x 152 My comments Barely 20/200 in left eye but gets .5 diopter bonus due to 20/15 BCVA. So this is equal to -3 and 20/20 BCVA for 20/200 UCVA. Right Eye 20/200 20/15 Left Eye 20/30 N/A (no surgery)   Refraction  Before After Right Eye -2.75 -0.50 x 180 0.00 Left Eye -0.75 - 0.50 x 10 N/A (no surgery) My comments -3 spherical equivalent in right eye, should be good enough for barely 20/150. Left eye barely had any refractive error so lasik wasnt warranted. -1 spherical equivalent blurs 20/15 into 20/30   You may read the rest of the testimonals yourself, I have commented on plenty. I will give the average tally after I am done reading them all. nondisclosed_email@example.com (Myope5)Mon, 24 Jul 2006 07:16:16 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p769,from=rss#post769https://bwelcometothevisionandeyeforums.runboard.com/p769,from=rss#post769http://la-sight.com/LS_commDetail.asp?index=0 While I already posted this lasik testimonals many posts back in this thread, I wish to elaborate the new results. There are over 200 results that show pre-lasik UCVA and post-lasik UCVA and the accompanying refraction. See my comments below. Educational read to better understand the correlation between diopters and 20/x Right Eye Hand Motions 20/20 Left Eye Hand Motions 20/20+   Refraction Before After Right Eye -9.00 -1.25 x045 0.00 -0.25 x084 Left Eye -8.00 -2.50 x175 +0.25 -0.25 x082 My comments 20/1600 to 20/2000 UCVA is so poor, all she could see was a hand waving at her! Everything was just a bunch of watercolors! Right Eye 20/80 20/15 Left Eye 20/80 20/15+   Refraction Before After Right Eye +2.00 -2.50 x 174 +0.25 -0.25 x 001 Left Eye +1.25 -1.25 x 007 0.00 -0.25 x 021 My comments I dont have a hyperopic diopter chart, but his UCVA should be better in the left eye given the lower prescription! Right Eye Counts Fingers 20/20 Left Eye Counts Fingers 20/20   Refraction  Before After Right Eye -11.50 -0.50 x 016 0.00 Left Eye -11.00 -0.25 x 168 -0.25 sph   My comments He chose PRK rather than phakic IOLs. Hes lucky to achieve 20/20 with such a strong myopic prescription. We are talking an objective blur of 20/2500. This is so bad, he sees 20 feet what perfect vision sees half mile! He is -.25 in the left, not bad enough to blur any measurable amount. -1.00 -0.50 x 154 for 20/40- distance, 20/20+ BCVA My comments 20/18 BCVA x2.5 blur multiplier = 20/45 Right Eye 20/200 20/20 Left Eye 20/400 20/20   Refraction  Before After Right Eye -2.00 -0.50 x 105 0.00 Left Eye -3.00 -0.25 x 179 0.00 -0.25 x 005 My comments Where is the 20/300 line on his eyechart? For the matter, where are the needed lines between 20/100 and 20/200 as well as 20/200 and 20/400? He would have an objective blur of 20/120(right eye) and just shy of 20/200(left eye) Right Eye 20/100 20/15 Left Eye 20/60 20/15   Refraction  Before After Right Eye -2.00 sphere 0.00 Left Eye -1.25 -0.50 x 85 0.00 -0.25 x 10 My comments Concides with my objective blur chart for 20/20 BCVA so im guessing she didnt have the right glasses/contacts *or* her blur interpretation wasnt so good. Right Eye 20/400 20/20+ Left Eye 20/400 20/20+   Refraction  Before After Right Eye -5.00 -0.75 x 179 0.00 Left Eye -5.00 -1.00 x176 +0.25 sph   My comments Objective blur would put her at 20/600 so its likley she squinted or just assumed there was an "E" even though she could see just a blurry smudge. Right Eye Counts Fingers 20/20 Left Eye 20/400 20/20-   Refraction  Before After Right Eye -3.00 -1.00 x084 0.00 -0.50 x108 Left Eye -2.00 -0.25 My comments He had mild cateracts which blurred in addition to his myopia. Got IOLs. Right Eye Counts Fingers 20/15- Left Eye Counts Fingers 20/15   Refraction  Before After Right Eye -4.25 0.00 Left Eye -4.00 -.25   My comments Should be able to see a blurry 20/400 "E" but after lasik hes 20/15 despite -.25 in one eye! Right Eye 20/200 20/20 Left Eye 20/200 20/20   Refraction  Before After Right Eye -3.00 -0.50 x109 0.00 -0.25 x146 Left Eye -2.00 -1.00 x071 0.00 My comments Wheres the 20/150 line on his eyechart? Left eye is better than 20/200, right eye barely 20/200. Right Eye 20/60- 20/15 Left Eye 20/70- 20/15+   Refraction  Before After Right Eye -1.25 -0.50 x176 0.00 Left Eye -2.00 -0.50 x005 0.00 My comments Lets see here. Left eye has better than 20/15, perhaps 20/12. Use 6x blur multiplier. Therefore we arrive at 20/72 Right eye we use 3x multiplier so he should be seeing 20/50, not a blurry 20/60!nondisclosed_email@example.com (Myope5)Mon, 24 Jul 2006 05:43:20 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p768,from=rss#post768https://bwelcometothevisionandeyeforums.runboard.com/p768,from=rss#post768My eyes seemed like they were horrible, but apparently I'm right in the median at -3.5 diopters (20/400) in each eye. (he got lasik and ended 20/20 in each eye, slightly better OU. He was 20/20 with glasses. Update: I have almost 20/12.5 vision, but something still doesn't feel "right" -- I read the 20/16 line perfectly easily, but had to strain on the 12.5 line to get 4/5 right. But still, my objective vision is much better than my subjective vision. Dunno if that's just psychological or what. Got my post-op today. 20/10 in right eye, 20/16 in left eye. I feel like I can see the future.) So what happens if your eyesight ranges above the capabilities of LASIK? An implantable lens called an IOL has recently been FDA approved for refraction up to -20 diopters (about 20/10,000 on vision charts). My comments: Although nearly 20/8000 on my objective blur chart, that is a good estimate. The snellen letters would need to be a little over 14 feet at 20/10000! If you already see very well with glasses or contacts, and see at least well enough to function reasonably well without them, then I would NOT get LASIK if I were you. Obviously, this cutoff point is subjective, and each person has to decide for himself if the expected improvement is worth the risk. I’d set a hard limit at 20/40 (the legal driving limit, representing, on average, -0.50D to -0.75D of spherical refractive error), and a softer limit at about -2.00D. Myopia this mild is very easily corrected with lightweight glasses or contact lenses. Of course, the presence of a lot of astigmatism changes things, but in the end, only you can decide if the risk is worth it. my comments: I agree, no point in lasik for mild myopia. You can consider orthoK which works extremely well for light prescriptions and its effects stick for days. -.5 diopters is going to be better than 20/40 in healthy eyes. Uncorrected vision, OD 20/100, OS 20/200. Significant myopia was found, as well as astigmatism in each eye. Best corrected vision was 20/30-2 in the right eye, 20/40+ in the left with a -1.00-1.50x85 OD, and -1.75-1.25x95 refractions shown, OD and OS respectively. my comments: Thats a spherical equivalent of -1.75 and -2.25 correctable at 20/30 to 20/40. If we use the objective blur formula and use thw 4x and 6x multiplier, we arrive at about 20/140 and 20/210 vision. I tested my own vision again with +3.5, +3.5 and +1 together, +3.5 and +3.5 together. This simulates -8.5, -9.5 and -12! My natural prescription is about -5 in the worse left eye that I used to simulate. I see 13/400 which makes me 20/600. At -8.5 I see 12/800 which makes me about 20/1330 and compenstating for magnification, it comes out to 20/1420. Looking at the objective blur chart...-8.5.......20/1438 So this proves my blur chart is right! At -9.5 I get 10/800 and compenstating for magnification thats 20/1760. at -12 I get 14/1600 and compenstating for magnification I get 20/2740. update: simulated -6 for 14/600 which got me 20/874 compenstating for magnification. comparsions between me and blur chart. -5=20/600 vs. 20/511 take -.5 penelity for 20/25 BCVA=20/614 -6=20/874 vs. 20/727 take -.5 penelity for 20/25 BCVA=20/849 -8.5=20/1420 vs. 20/1438 -9.5=20/1760 vs. 20/1791 -12=20/2740 vs. 20/2846 I didnt take penelity for the high myopia simulations because I wanted to avoid this variable. I did not exactly measure the distance, I know how far give or take a few inches. The magnification calculations get tricky with two pairs of plus glasses due to vertex distance. Even the blur interpretion is subjective. I will do more testing with this, but the fact im extremely close, well within the margin of error confirms that my objective blur chart formula is correct and accurate The second procedure is an accelerated Ortho-K treatment that rapidly returns a patient to functional, natural vision within a couple of days to a couple of weeks. This method is used for patients with mild to moderate myopia up to -4.50-5.00D. of correction with uncorrected vision of up to 20/400-500 acuity. Dr. Kearney uses his own lens design, the C.C.C. lens, which is a new multicontouring lens design that is now available to orthokeratologists. My comments: agrees with objective blur chart. A 31-year-old healthy woman had bilateral laser in situ keratomileusis (LASIK) 10 months ago. According to the patient's file, the preoperative refraction was approximately -5.75 -0.50 × 175 in the right eye and -5.25 -0.75 × 175 in the left eye. The best corrected visual acuity (BCVA) was 20/20 to 20/16 (after lasik----->)The UCVA is 20/50 in the right eye and 20/25 in the left eye and the BCVA, 20/16 with -1.00 -0.50 × 0 and 20/20 with -0.25 -0.25 × 10, respectively OS: -6.00D, -1.50D OD: -5.50D, -0.25D OS: 20/1200* OD: 20/1000 OU: 20/1000 *Beyond about 20/400, Snellen Acuity measurements are pretty meaningless. I gauged this based upon a homemade Snellen chart with some really huge letters. Per my blur formula, he "should" measure at 20/600(actually about 20/650) in the better eye and near 20/1000 in the worse(about 20/950) His worse eye has a -6.75 spherical equivalent but based on his own snellen measure, his cylindar does not appear to contribuate much to blur in his own subjective measure. A patient with a refractive error of 1 D will have approximately 20/40 vision, ... error of 2 D will result in vision ranging from 20/100 to 20/200. My comments: Found this off a website that no longer exists. I agree with the -1 correlation to 20/40. They gave a broad range for -2, but I disagree that -2 is anywhere near 20/200. I would put the range more like 20/80 to 20/120. I am a victim of near-sightedness. Myopic of 20/200. Perscription is about -2.0 or something. P.S. my vision is corrected better then 20/20. By the way im not getting any sort of laser surgery if I don't have to. It is permanent and I personally don't want anything removed from my eyeballs that will never grow back. It would weaken my eye structure. My comments: He does not know his exact prescription, but im guessing hes -2.5 with some cylindar which would blur him worse than 20/100 and most eyecharts have nothing in between. I wear soft contacts now and my vision prescription is -5.50 in my left eye and -5.25 in my right. Is there any other option for me besides PRK? With my prescription, it's probably around 20/600...20/700. My comments: This ones tricky. His glasses prescription could be as low as -5.5 or as high as -7. The two arent directly comparable, however per my objective blur chart, -5.5=20/600 and -6.25=20/800 so depending on his glasses prescription, hes more likley to be about 20/800 and likley somewhat worse than 20/600. If my vision is around 20/30-20/40 My eye exam about 3 weeks ago said I am -.75 in each eye which equates to around 20/40 so hopefully all goes well My comments: He will have no problem seeing 20/40 and will see some or even all of the 20/30 line. He even said hes 20/30 to 20/40. I spent $2500 for both eyes. I wore contacts wiith a prescription of -1.25 and -1.50. The best I could muster without the contacts was 20/70 and 20/100 for visual aquity. He got PRK and ended up 20/15! My comments: This doesnt sound right and he should have better UCVA than this. If we assume vertex distance, he would be about -1.5 and -1.75 in glasses, in truth his worse eye between -1.75 and -2 but I rounded down.(better to undercorrect than overcorrect in my opinion) And if he really is capable of 20/15, his UCVA should be 20/50 and 20/70 at worst. most rx's over say -4.00 cant read the 20/400 letters w/o squinting. *This is what one optometrist speaks from experience you are not 20/200 with -7.50. again you are more like 20/1000. *Optometrist's estimate. Pretty obvious how bad -7.5 is(I say about 20/1200) I have a refraction of -6.75 sph -1.00 cyl in one eye and -5.25 sph -0.50 cyl in the other, yet have an uncorrected distant visual acuity of 20/200 (correctable to 20/12). I tend to leave optometrists shaking their heads, saying "that couldn't possibly be right", since most patients they see with that level of refractive error tend to have DVA's of 20/400 to 20/800. My comment: Accroding to my objective blur chart, hes a -5.5 spherical equivalent in the better eye. Because of his superior BCVA of 20/12 *with* spectacle minification, that accounts for a one diopter bonus(well almost but close enough)so with the bonus, this puts the blur at barely 20/400. Several reasons arise why he is seeing twice as well. Squinting is the most likley case. Some people when they blink, do slowly so for a split second before the eye closes completely, see clearer for that instant. Other reasons could be the lighting is too bright causing the pupil to constrict and act like a pinhole. Perhaps he doesnt need this much minus or perhaps hes guessing, cheating, memorizing or even perhaps he has extremely good blur preception. I am in agreement that with a prescription that high, youd normally be at 20/600 with a "fair" test assessing your UCVA. nondisclosed_email@example.com (Myope5)Sat, 22 Jul 2006 04:14:19 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p767,from=rss#post767https://bwelcometothevisionandeyeforums.runboard.com/p767,from=rss#post767I found more diopter conversions, diopter to 20/x Refractive index is measured in diopters. A diopter is a unit based on the focal length (power) of a lens. A person with one diopter of myopia sees about 20/50 without corrective lenses. This means they see objects at twenty feet that people with normal vision see at fifty feet. For people who have one diopter of myopia, objects would begin to blur at three to four feet and they would need glasses for board work, movies, and driving. A person with three diopters of myopia would have 20/400 vision without correction. He or she would need to wear corrective lenses all the time. Without glasses, these people would only be able to see about one foot without a blurring of their vision. my comments: Sounds very close or about right for how much blur -1 diopter causes. They would see perfect from near at 39 inches, or a little over 3 feet. I doubt you experience 20/400 blur from -3 it should be more like 20/300 or even 20/200! Your near vision would be 13 inches or just over a foot. http://www.agingeye.net/myopia/myopiaindex.php 0.75 diopter of myopia reduces vision to 20/40 and the visual efficiency is reduced to 83% (20/20 is 100% visual efficiency). 20/40 vision is the cut-off used in most states for getting a driver's license. At or above 0.75 diopter of uncorrected myopia, you will fail the vision test to get a driver's license. • 1.50 diopter of myopia reduces vision to 20/80 level and the visual efficiency is reduced to 58%. • 2.50 diopter of myopia reduces vision to 20/200 level and the visual efficiency is reduced to 20%. 'Best corrected' vision worse than 20/200 is the 'legal definition of blindness'. Therefore at or above 2.50 diopter of 'uncorrected' myopia the eyesight is reduced to a vision-level that defines 'legal blindness'. Without glasses or contact lenses, a myope of -2.50 D sees what a legally blind person is able to see. my comments: -.75 diopters more commonly blurs to 20/30, but for someone with slightly less than 20/20 BCVA, he may experience 20/40 UCVA. -1.5 tends to blur a little less than 20/80, generally 20/60 to 20/70 in eyes that correct to 20/20. For 20/25 BCVA, 20/80 UCVA sounds right. -2.5 is a pretty good estimate for 20/200 UCVA and another reason is alot of eyecharts have no lines between 20/100 and 20/200. Someone correctable to 20/20 possibly will see a little better than 20/200 at -2.5, perhaps 20/160. Ive noticed that -3 is generally the limit for 20/200 UCVA if 20/20 BCVA. -2.5 is a little less than that, a little better than 20/200 Q. What is a Diopter? A. A diopter is a unit of measurement of the lens focusing power. Each 1/4 of a diopter of nearsightedness will blur a person's vision by 1 to 2 lines on the eye chart. Therefore, the following are approximate uncorrected values: -1.00 = 20/60 -2.00 = 20/200 -3.00 = 20/400 -4.00 = 20/800 -5.00 = 20/1,200 -6.00 = 20/2,000 my comments: Those figures came from a lasik website and are exaggerated to make people believe that their eyes are so bad they must run out and get lasik! At least they are pretty close on the mark for -1, the other lasik website states youd see 20/50. -1 is a very common prescription and seemly a popular first glasses prescription. Ive done much reserch on -1 and it appears that 20/50 is the most common result/figure/estimate/value. Ive seen the 20/50 value for -1 in over 20 different places. Ive seen anywhere from 20/25 to 20/200 acuity. No one with normal 20/20 to 20/25 BCVA is going to see worse than 20/50 to 20/70 with only a single diopter of myopia. An optometrist said in a message board that most of his -1 patients(usually children) see 20/40 with some seeing 20/30. BCVA is often 20/20 and sometimes 20/15. He also said at -2 vision is 20/80 or so. It seems that alot of sites throw out 20/200 for -2 diopters. Probably a rounding thing and also because most eyecharts have no lines between 20/100 and 20/200. Someone could be just shy of 20/100 but be marked down as 20/200 as its the next line up   I would say -2 corresponds to 20/100, this is the case per my objective blur chart. For -3, I see figures of acuity show 20/200, 20/300 or 20/400. -3 is probably going to be 20/200 or a bit worse like 20/250 for most people with 20/20 BCVA. for -4, most figures put it at 20/400, but some say worse than 20/400 or mention its the point of "count finger" vision. There is no way -4 blurs to 20/800, im near or at -5 in the worse eye and even I can see 20/800 easily and even 20/600 although barely. I know someone else who was -5 and he measured 13 feet to see the 20/400 E. I recall reading an army website say reguarding passing 20/400 UCVA requirements and they said if you are -4 or less, you "should" pass, if not ask for a second opinion and get tested again. If you are -4.5 you have an even chance to pass/fail. If you are -5, nearly all will fail, they throw in the towel and get lasik. If you are more than -5, forget it, dont even bother. For -5, you are almost certain to be worse than 20/400 accroding to my objective blur chart. Most healthy eyes should manage 20/600 and any that cant see even 20/800 have some occular pathalogy with poor BCVA worse than 20/40. For -6 your probably gonna have a hard time seeing 20/800 and some with less than great blur interpretition or slightly worse than 20/20 BCVA, you may be at 20/1000 or even 20/1200. There was someone at -7 who was tested at 20/1200. Probably stood 6.7 feet from the 20/400 E to arrive at that. Because standing 2 meters away cancels half diopter, he was in essence 20/1200 at -6.5 >e.g. if someone is -4.5 sph, is that 20/100, 20/200, or what? Optometrist says: Too many variables for a formula. I'd guess your uncorrected VA is 20/400 to 20/600 if your eyes are healthy. my comments: That makes sense per my objective blur chart. Would be the limit of 20/400. Id say 20/500 sounds more like it The two measures are not related in a way that is predictable, uncorrected acuity depends not only on Rx but on light level, pupil size, lid squinting, your individual willingness to guess and your ability to deduce letters from there shape, test distance (whether 5 ft, 10 ft or 20 ft). If you want to know your unaided acuity, have it measured. With an Rx over -4, by rule of thumb, you likely have unaided acuity worse than 20/400. My comments: You can control the variables. The standard for testing vision is indoors in low light with the eyechart illuminated. Pinhole effect should be eliminated with dilated pupils of 6mm or larger and minimized with 5mm pupils. Squinting is an absolute NO NO. One guy was -4 and 20/200 with 20/25 BCVA. I told him thats impossible and he finally admit he squinted a little. I said that doesnt count, its cheating. He would likley be barely 20/400 per my objective blur chart. Test distance should be 20 feet to simulate infinity. This person did say -4 is the cutoff for 20/400 as it will be so blurry as to barely be able to discern. Yes. There are a lot of us. 20/400 would take about -3.25 Diopters to correct to 20/20. 20/600 would take about -3.75 Diopters to correct to 20/20 I myself need about -6.50 D to correct my right eye to 20/20, which is so much that it doesn't make any sense to try to write it in 20/ notation. I need about -4.25 D to correct my left eye to 20/20. My comments: How does this person know? And he could test it himself to see if hes 20/400 or even 20/600 in the -4.25 eye. I would put him at 20/400 in the better eye and 20/1000 in the worse. *countinued on post below*nondisclosed_email@example.com (Myope5)Tue, 18 Jul 2006 04:10:44 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p766,from=rss#post766https://bwelcometothevisionandeyeforums.runboard.com/p766,from=rss#post766As of October 1994, according to Taylor's doctor, her vision was 20/25 without glasses and 20/20 with glasses, and her correction was -0.75 diopter. Taylor says she still has some trouble with night glare and needs glasses to drive at night, but she's delighted with the results. "For the first time in my life that I could remember, I could see my feet in the shower," she says. My comments: Although generally considered 20/30, its possible to be 20/25 at -.75 with factors like good blur perception, small pupils, bright light(eye exams should be in dim light) slightly better than 20/20 BCVA but not fully 20/15. If you look at my blur multiplier, she could be 20/16.7 times 1.5 for 20/25 since -.75 you use 1.5x Another possibility is she is between -.5 and -.75 so either lens would get her to 20/20, no one can tell such a small difference, quarter diopters is the smallest thats why its measured this way and not in tenths. My brother is 20/60 in his -1 sphere, -.5 cylindar eye and 20/100 in his -1.25 sphere, -.75 cylindar. A more recent test revealed 20/50 in his -1 sphere and 20/100 in his -1.75 sphere. BCVA was 20/20- in the better eye, 20/25 in the worse. The -1 lens in the better eye when tried in the worse got him 20/40 with -.75 undercorrection given 20/25 BCVA. -.5 undercorrection yielded 20/30 instead of 20/25. This goes concisely with my objective blur chart. nondisclosed_email@example.com (Myope5)Wed, 12 Jul 2006 03:58:05 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p765,from=rss#post765https://bwelcometothevisionandeyeforums.runboard.com/p765,from=rss#post765I am trying to make a circle blur formula for visual accuracies better or worse than 20/20 but I have a hard time figuring out the math for anything other than baseline 20/20. However I believe using bonus and penelty works just as well. If you see the above post, for myopia up to -3, using bonus instead of blur multiplier tends to give better UCVA than actual. For penelty, it gives worse UCVA than actual. However with BCVA worse than 20/50, always use the penelty formula reguardless of diopters of myopia. For 20/40, use the multiplier up to -2 and for 20/50, up to -1.5 I will do the math for the examples below to save you time. I did not use any rounding(except if results ended in decimal then round to nearest whole number) for -3 and below to show the results of the multiplier. For over -3 I used the rounded to snellen verson instead of simple rounded verson. 20/8 BCVA use multiplier to -3 then bonus of 1.25 -.5.......20/10 -.75.......20/12 -1.........20/16 -1.25.......20/20 -1.5........20/24 -1.75........20/32 -2...........20/40 -2.25........20/48 -2.5.........20/56 -2.75.........20/68 -3...........20/80 -3.25.......20/100 -3.5.......20/120 -3.75.......20/140 -4..........20/170 -4.25.......20/200 -4.75........20/250 -5..........20/300 -5.75.......20/400 -6.25.......20/500 -6.75.......20/600 -7.5.........20/800 20/10 BCVA use multiplier to -3 then bonus of 1.00 -.5.......20/13 -.75.......20/15 -1.........20/20 -1.25.......20/25 -1.5........20/30 -1.75........20/40 -2...........20/50 -2.25........20/60 -2.5.........20/70 -2.75.........20/85 -3...........20/100 -3.25.......20/120 -3.5.......20/140 -3.75.......20/170 -4..........20/200 -4.5........20/250 -4.75..........20/300 -5.5.......20/400 -6.......20/500 -6.5.......20/600 -7.25.........20/800 20/13 BCVA use multiplier to -3 then bonus of .75 -.5.......20/16 -.75.......20/20 -1.........20/26 -1.25.......20/33 -1.5........20/39 -1.75........20/52 -2...........20/65 -2.25........20/78 -2.5.........20/91 -2.75.........20/111 -3...........20/130 -3.25.......20/140 -3.5.......20/170 -3.75.......20/200 -4.25........20/250 -4.5..........20/300 -5.25.......20/400 -5.75.......20/500 -6.25.......20/600 -7..........20/800 20/15 BCVA use multiplier to -3 then bonus of .5 -.5.......20/19 -.75.......20/23 -1.........20/30 -1.25.......20/38 -1.5........20/45 -1.75........20/60 -2...........20/75 -2.25........20/90 -2.5.........20/105 -2.75.........20/128 -3...........20/150 -3.25.......20/170 -3.5.......20/200 -4........20/250 -4.25..........20/300 -5.......20/400 -5.5.......20/500 -6.......20/600 -6.75..........20/800 20/20 BCVA use multiplier to -3 then no bonus/penelty -.5.......20/25 -.75.......20/30 -1.........20/40 -1.25.......20/50 -1.5........20/60 -1.75........20/80 -2...........20/100 -2.25........20/120 -2.5.........20/140 -2.75.........20/170 -3...........20/200 -3.5.......20/250 -3.75..........20/300 -4.5.......20/400 -5.......20/500 -5.5.......20/600 -6.25..........20/800 20/25 BCVA use multiplier to -3 then penelty of .5 -.5.......20/31 -.75.......20/38 -1.........20/50 -1.25.......20/63 -1.5........20/75 -1.75........20/100 -2...........20/125 -2.25........20/150 -2.5.........20/175 -2.75.........20/213 -3...........20/250 -3.25.......20/300 -4..........20/400 -4.5.......20/500 -5.......20/600 -5.75.......20/800 20/30 BCVA use multiplier to -3 then penelty of .75 -.5.......20/38 -.75.......20/45 -1.........20/60 -1.25.......20/75 -1.5........20/90 -1.75........20/120 -2...........20/150 -2.25........20/180 -2.5.........20/210 -2.75.........20/255 -3...........20/300 -3.75.......20/400 -4.25..........20/500 -4.75.......20/600 -5.5.......20/800 20/40 BCVA use multiplier to -2 then penelty of 1.00 -.5.......20/50 -.75.......20/60 -1.........20/80 -1.25.......20/100 -1.5........20/120 -1.75........20/160 -2...........20/200 -2.5.........20/250 -2.75.........20/300 -3.5..........20/400 -4..........20/500 -4.5..........20/600 -5.25.......20/800 20/50 BCVA use multiplier to -1.5 then penelty of 1.25 -.5.......20/63 -.75.......20/75 -1.........20/100 -1.25.......20/125 -1.5........20/150 -1.75........20/200 -2.25...........20/250 -2.5.........20/300 -3.25.........20/400 -3.75..........20/500 -4.25..........20/600 -5........20/800 I hope this makes sense! This is what your objective blur should be. nondisclosed_email@example.com (Myope5)Sun, 11 Jun 2006 00:06:15 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p764,from=rss#post764https://bwelcometothevisionandeyeforums.runboard.com/p764,from=rss#post764Countinued from above post. By now you know my formula. What if someone has a BCVA other than 20/20 which my formula is based on? How will this factor in? Simple! I mentioned in above post about "bonus" and "penalty" Heres how it works: 20/8=1.25 diopter bonus 20/10=1 diopter bonus 20/13=.75 diopter bonus 20/15=.5 diopter bonus 20/20=baseline 20/25=.5 diopter penalty 20/30=.75 diopter penalty 20/40=1 diopter penalty 20/50=1.25 diopter penalty The logic is simple. If someone has a better than 20/20 BCVA, he has few high order aberrations and possibily higher density of cones. Likewise a lower BCVA means the opposite. The figures above should concide with my diopter chart. For example, a 20/25 BCVA gets a half diopter penalty because half diopter myopia blurs your 20/20 into 20/25. The difference is a 20/25 BCVA has any of a number of factors that glasses can not correct. There is yet another formula thats more accurate than bonus/penalty for low dioptric values. Its called the blur multiplier. It concides with my other formulas -.5=1.25x blur(20x1.25=25) -.75=1.5x blur(20x1.5=30) -1=2x blur(20x2=40) -1.25=2.5x blur(20x2.5=50) -1.5=3x blur(20x3=60) -1.75=4x blur(20x4=80) -2=5x blur(20x5=100) -2.25=6x blur(20x6=120) -2.5=7x blur(20x7=140) -2.75=8.5x blur(20x8.5=170) -3=10x blur(20x10=200) Minor rounding was used to make it simple to remember and also correspond to actual snellen lines. Lets compare the accuracy of bonus/penalty vs. the blur multiplier.(bonus/penalty vs. multiplier) Take a 20/8 BCVA(1.25 bonus) -.5(20/13 vs. 20/10) -.75(20/15 vs. 20/12) -1(20/20+ vs. 20/16) -1.25(20/20 vs. 20/20) -1.5(20/20- vs. 20/24) -1.75(20/25 vs. 20/32) -2(20/30 vs. 20/40) -2.25(20/40 vs. 20/48) -2.5(20/50 vs. 20/56) -2.75(20/60 vs. 20/68) -3(20/80 vs. 20/80) Take a 20/10 BCVA(1.00 bonus) -.5(20/15 vs. 20/13) -.75(20/20+ vs. 20/15) -1(20/20 vs. 20/20) -1.25(20/20- vs. 20/25) -1.5(20/25 vs. 20/30) -1.75(20/30 vs. 20/40) -2(20/40 vs. 20/50) -2.25(20/50 vs. 20/60) -2.5(20/60 vs. 20/70) -2.75(20/80 vs. 20/85) -3(20/100 vs. 20/100) Take a 20/13 BCVA(.75 bonus) -.5(20/20+ vs. 20/15) -.75(20/20 vs. 20/20) -1(20/20- vs. 20/25) -1.25(20/25 vs. 20/30) -1.5(20/30 vs. 20/40) -1.75(20/40 vs. 20/50) -2(20/50 vs. 20/65) -2.25(20/60 vs. 20/80) -2.5(20/80 vs. 20/90) -2.75(20/100 vs. 20/110) -3(20/120 vs. 20/130) Take a 20/15 BCVA(.5 bonus) -.5(20/20 vs. 20/20) -.75(20/20- vs. 20/25) -1(20/25 vs. 20/30) -1.25(20/30 vs. 20/40) -1.5(20/40 vs. 20/45) -1.75(20/50 vs. 20/60) -2(20/60 vs. 20/75) -2.25(20/80 vs. 20/90) -2.5(20/100 vs. 20/105) -2.75(20/120 vs. 20/130) -3(20/140 vs. 20/150) You already know the baseline math(for 20/20) Take a 20/25 BCVA(.5 penelty) -.5(20/40 vs. 20/30) -.75(20/50 vs. 20/40) -1(20/60 vs. 20/50) -1.25(20/80 vs. 20/60) -1.5(20/100 vs. 20/75) -1.75(20/120 vs. 20/100) -2(20/140 vs. 20/125) -2.25(20/170 vs. 20/150) -2.5(20/200 vs. 20/175) -2.75(20/250 vs. 20/200) -3(20/300 vs. 20/250) Take a 20/30 BCVA(.75 penelty) -.5(20/50 vs. 20/40) -.75(20/60 vs. 20/50) -1(20/80 vs. 20/60) -1.25(20/100 vs. 20/75) -1.5(20/120 vs. 20/90) -1.75(20/140 vs. 20/120) -2(20/170 vs. 20/150) -2.25(20/200 vs. 20/180) -2.5(20/250 vs. 20/200) -2.75(20/300 vs. 20/250) -3(20/300 vs. 20/300) Take a 20/40 BCVA(1.00 penelty) -.5(20/60 vs. 20/50) -.75(20/80 vs. 20/60) -1(20/100 vs. 20/80) -1.25(20/120 vs. 20/100) -1.5(20/140 vs. 20/120) -1.75(20/170 vs. 20/160) -2(20/200 vs. 20/200) -2.25(20/250 vs. 20/240) -2.5(20/300 vs. 20/280) -2.75(20/300 vs. 20/340) -3(20/350 vs. 20/400) Take a 20/50 BCVA(1.25 penelty) -.5(20/80 vs. 20/60) -.75(20/100 vs. 20/75) -1(20/120 vs. 20/100) -1.25(20/140 vs. 20/125) -1.5(20/170 vs. 20/150) -1.75(20/200 vs. 20/200) -2(20/250 vs. 20/250) -2.25(20/300 vs. 20/300) -2.5(20/300 vs. 20/350) -2.75(20/350 vs. 20/400) -3(20/400 vs. 20/500) nondisclosed_email@example.com (Myope5)Wed, 07 Jun 2006 05:46:38 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p763,from=rss#post763https://bwelcometothevisionandeyeforums.runboard.com/p763,from=rss#post763I have devised a new formula that is likley to be much more accurate because it attempts to measure blur from an objective point. I still have my subjective blur formula at the start of this thread. The new formula takes into account the radius of the blur circle. This is something that gets expotentionally bigger the more myopic you are. For cylindar, take the spherical equivalent. The main formula is based on 20/20 BCVA, compenstating for spectacle minification(you know this by now from my previous posts)For better than 20/20, take a "bonus" for worse than 20/20 take a "penalty" This will be explained in the post below this one. Lets do the main formula first. radius squared times PI=blur area blur area divide by 4=blur factor multiply blur factor by 100 and add 20=UCVA 0(0x0x3.14=0)(0/4=0)(0x100+20=20)20/20 -.25(.125x.125x3.14=.049)(.049/4=.012)(.012x100+20=21.2)20/21.2 -.5(.25x.25x3.14=.196)(.196/4=.049)(.049x100+20=24.9)20/24.9 -.75(.375x.375x3.14=.442)(.442/4=.11)(.11x100+20=31)20/31 -1(.5x.5x3.14=.785)(.785/4=.196)(.196x100+20=39.6)20/39.6 -1.25(.625x.625x3.14=1.227)(1.227/4=.307)(.307x100+20=50.7)20/50.7 -1.5(.75x.75x3.14=1.766)(1.766/4=.442)(.442x100+20=64.2)20/64.2 -1.75(.875x.875x3.14=2.404)(2.404/4=.601)(.601x100+20=80.1)20/80.1 -2(1x1x3.14=3.14)(3.14/4=.785)(.785x100+20=98.5)20/98.5 -2.25(1.125x1.125x3.14=3.974)(3.974/4=.994)(.994x100+20=119.4)20/119.4 -2.5(1.25x1.25x3.14=4.901)(4.901/4=1.227)(1.227x100+20=142.7)20/142.7 -2.75(1.375x1.375x3.14=5.937)(5.937/4=1.484)(1.484x100+20=168.4)20/168.4 -3(1.5x1.5x3.14=7.065)(7.065/4=1.766)(1.766x100+20=196.6)20/196.6 -3.25(1.625x1.625x3.14=8.292)(8.292/4=2.073)(2.073x100+20=227.3)20/227.3 -3.5(1.75x1.75x3.14=9.616)(9.616/4=2.404)(2.404x100+20=260.4)20/260.4 -3.75(1.875x1.875x3.14=11.039)(11.039/4=2.76)(2.76x100+20=296)20/296 -4(2x2x3.14=12.56)(12.56/4=3.14)(3.14x100+20=334)20/334 -4.25(2.125x2.125x3.14=14.179)(14.179/4=3.545)(3.545x100+20=374.5)20/374.5 -4.5(2.25x2.25x3.14=15.896)(15.896/4=3.974)(3.974x100+20=417.4)20/417.4 -4.75(2.375x2.375x3.14=17.712)(17.712/4=4.428)(4.428x100+20=462.8)20/462.8 -5(2.5x2.5x3.14=19.625)(19.625/4=4.906)(4.906x100+20=510.6)20/510.6 -5.5(2.75x2.75x3.14=23.746)(23.746/4=5.937)(5.937x100+20=613.7)20/613.7 -6(3x3x3.14=28.26)(28.26/4=7.065)(7.065x100+20=726.5)20/726.5 -6.5(3.25x3.25x3.14=33.166)(33.166/4=8.292)(8.292x100+20=849.2)20/849.2 -7(3.5x3.5x3.14=38.465)(38.465/4=9.616)(9.616x100+20=981.6)20/981.6 -7.5(3.75x3.75x3.14=44.156)(44.156/4=11.039)(11.039x100+20=1123.9)20/1123.9 -8 (4x4x3.14=50.24)(50.24/4=12.56)(12.56x100+20=1276)20/1276 -8.5(4.25x4.25x3.14=56.716)(56.716/4=14.179)(14.179x100+20=1437.9)20/1437.9 -9(4.5x4.5x3.14=63.585)(63.585/4=15.896)(15.896x100+20=1609.6)20/1609.6 -9.5(4.75x4.75x3.14=70.846)(70.846/4=17.712)(17.712x100+20=1791.2)20/1791.2 -10(5x5x3.14=78.5)(78.5/4=19.625)(19.625x100+20=1982.5)20/1982.5 -11(5.5x5.5x3.14=94.985)(94.985/4=23.746)(23.746x100+20=2394.6)20/2394.6 -12(6x6x3.14=113.04)(113.04/4=28.26)(28.26x100+20=2846)20/2846 -13(6.5x6.5x3.14=132.665)(132.665/4=33.166)(33.166x100+20=3336.6)20/3336.6 -14(7x7x3.14=153.86)(153.86/4=38.465)(38.465x100+20=3866.6)20/3866.5 -15(7.5x7.5x3.14=176.625)(176.625/4=44.156)(44.156x100+20=4435.6)20/4435.6 -16(8x8x3.14=200.96)(200.96/4=50.24)(50.24x100+20=5044)20/5044 -17(8.5x8.5x3.14=226.865)(226.865/4=56.716)(56.716x100+20=5691.6)20/5691.6 -18 (9x9x3.14=254.34)(254.34/4=63.585)(63.585x100+20=6378.5)20/6378.5 -19(9.5x9.5x3.14=283.385)(283.385/4=70.846)(70.846x100+20=7104.6)20/7104.6 -20(10x10x3.14=314)(314/4=78.5)(78.5x100+20=7870)20/7870 Simple, rounded verson: 0...........20/20 -.25.......20/21 -.5.........20/25 -.75.......20/31 -1..........20/40 -1.25.....20/51 -1.5.......20/64 -1.75.....20/80 -2..........20/99 -2.25.....20/119 -2.5.......20/143 -2.75.....20/168 -3..........20/197 -3.25.....20/227 -3.5.......20/260 -3.75.....20/296 -4..........20/334 -4.25.....20/375 -4.5.......20/417 -4.75.....20/463 -5..........20/511 -5.5.......20/614 -6..........20/727 -6.5.......20/849 -7..........20/982 -7.5.......20/1124 -8..........20/1276 -8.5.......20/1438 -9..........20/1610 -9.5.......20/1791 -10........20/1983 -11........20/2395 -12........20/2846 -13........20/3337 -14........20/3867 -15........20/4436 -16........20/5044 -17........20/5692 -18........20/6379 -19........20/7105 -20........20/7870 Havent bothered doing the math past that as 20/7870 means a letter measuring 11.15 feet large! If you go by my simple formula, you can calculate for any dioptric values! rounded to snellen eyechart verson: 0...........20/20 -.25.......20/20 -.5.........20/25 -.75.......20/30 -1..........20/40 -1.25.....20/50 -1.5.......20/60 -1.75.....20/80 -2..........20/100 -2.25.....20/120 -2.5.......20/150 -3..........20/200 -3.5.......20/250 -3.75.....20/300 -4.5.......20/400 -5..........20/500 -5.5.......20/600 -6.25.......20/800 -7..........20/1000 -7.75..........20/1200 -9..........20/1600 See post below for countinuation of this formula nondisclosed_email@example.com (Myope5)Tue, 23 May 2006 23:14:54 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p762,from=rss#post762https://bwelcometothevisionandeyeforums.runboard.com/p762,from=rss#post762in another forum, someone said this: interesting question, and only an approximate answer possible. typically -1.00 is about 20/40, by -1.50 vision is 20/80 to 20/100, and at -2.00 about 20/200. -3.00 about 20/400. Above -4.00 20/600 or worse. the real answer depends on the optics of corneal curvature vs axial length - an eye with steep cornea and average length can be equally nearsighted with an eye with a flat cornea that is very long - but they may not have the same uncorrected acuity. Some eyes are -8.00 and 20/400, just like some eyes that are -3.00. Vision decreases seemingly exponentially with increasing prescription, and quickly reaches 20/200 or legal blindness. Beyond that blurry is blurry and hard to distinguish as far as distance vision goes. my comments: It seems like almost everyone agrees that -1 corresponds to 20/40(20/20 BCVA is assumed) Ive seen others say it can be 20/30 to 20/50 but thats likley due to BCVA's of better or worse than 20/20. I do disagree on his other assetments. -1.5 is going to definately be better than 20/100 if you correct to 20/20. I remember being 20/70 to 20/80 back when I was -1.5 and I couldnt quite correct to 20/20 either! As for -2 being 20/200, I see that all the time but in reality its 20/100 and even those that cant quite see 20/100, they are not 20/200 but just shy of 20/100. Too bad many eyecharts have nothing between 20/100 and 20/200. -3 is commonly 20/200 but definately better than 20/400. -4 tends to fall at 20/300 to 20/400 and occasionally 20/200 if you have a very good BCVA. -5 however is usually worse than 20/400. I strongly disagree with cornea curvature vs. axial blur. Its equal for both or contacts and lasik would have unexpected results. It does not matter what is causing diopters of blur, its all the same amount of defocus. Your cornea can be too steep or your eye too long, either way is equal blur if equal diopters of defocus. I do agree on the exponental blur in respect to diopters. I will explain why. As for 20/200 or worse looking almost the same, thats not true! I am 20/600 uncorrected and I can see a very big difference at 20/200 with undercorrecting glasses. Likewise with reading glasses to get me below 20/1200, I can see so much more blur! nondisclosed_email@example.com (Myope5)Tue, 23 May 2006 21:58:28 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p761,from=rss#post761https://bwelcometothevisionandeyeforums.runboard.com/p761,from=rss#post761another case study example. You will see I have posted about 50 examples in my previous posts reguarding the diopter correlation to visual accuracy. I also have mentioned before that -.5 diopter costs only one line and that -.75 diopters costs 2 lines. A 48-year-old female with no significant ocular history presented for LASIK in April 1999. Preoperative examination revealed uncorrected visual acuity of 20/160 in the right eye and 20/160 in the left eye. Best spectacle-corrected vision was 20/20 in both eyes. Cycloplegic refraction was –2.75 +0.75 ×180° in the right eye and –3.00 +1.00 ×180° in the left eye. my comments: spherical equivalent of -2.5 so this is a little shy of 20/100. I guess the next line on shown eyechart was 20/160. At 3 months following enhancement of the right eye and 11 months following LASIK treatment of the left eye, the patient noted that the vision and dryness symptoms appeared to be improving, especially in the left eye. Uncorrected visual acuity was 20/20 in the right eye and 20/25 in the left eye. Manifest refraction was –0.50 D in the right eye and –0.75 D in the left eye with best spectacle corrected visual acuity of 20/15. my comments: This is impossible for her to "magically" improve to 20/15 BCVA. Theres several logic explanations, please refer to the lasik section in my forum. Nonwithstanding the issues with lasik, this example shows the correlation of diopters to UCVA.nondisclosed_email@example.com (Myope5)Sat, 06 May 2006 22:23:45 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p760,from=rss#post760https://bwelcometothevisionandeyeforums.runboard.com/p760,from=rss#post760If I can tolerate orthoK(much easier to do so from the people I know who tell me) itll be worth it. I can remove orthoK when I wake up and all the hassles with it. For the remainder of the day ill have clear, uncorrected vision and I can even swim without worrying about losing a contact because there is none! Your right about forgetting to put in orthoK some nights. Not a big deal if your eyes arent bad, this is where natural vision comes. I can get my -5 down to -3 then orthoK can take care of the rest. Also it takes like 2 weeks to fully regress. Ill regress to maybe -1 at most if I forget a night or two of orthoK and -1 isnt a big deal, my bro is -1.25 and doesnt need glasses except for driving and even then he isnt legally required to wear glasses to drive, he chooses to do so for good measure. His uncorrected vision is only slightly reduced from his best corrected vision. He sees and reads text from a great distance without glasses. We dont understand why some at -1 make a big deal. They must be so super picky! I asked him at what point would glasses be considered a neccessary and he says at least -2 and in some cases, closer to -3. Therefore if I can improve to -2 I will be almost free from glasses and see quite clearly! Myopia is expotentional and each diopter compounds the blur. I do not know on what expotentional scale this is based on, however -2 is more than twice as bad as -1(about 2.5x I heard) and -4 is on the order of almost 4 times as bad as -2 from what I hear! Each diopter higher adds alot more to the blur. I heard that if I improve from -5 to -3 Ill be seeing nearly three times better! I know this lady who was -10.5 with so much blur she was nearly blind. When she described how bad the blur was, I shuddered! When I asked her how far she can count fingers, she said I cant really even count fingers! I hold my hand arm length(about 2 feet, short arms) and I just see a pinkish blob! If she drops her glasses, someone has to pick them up or she can spend many minutes fumbling for them by feel. Without her glasses, she bumps into walls and objects! When I asked if she can read the eyechart, she laughed and said, what eyechart? I cant even tell if theres an eyechart, let alone read it! From what I heard, I have composed the estimated snellen equivalent. One such optometrist who posts online mentioned figures like that which I have shown below: <-1 = 20/20 or just shy of 20/20 -1 = 20/40 -1.25 = 20/50 -1.5 = 20/60 -1.75 = 20/80 -2 = 20/100 -2.5 = 20/150 -3 = 20/200 -3.5 to -4 = 20/300 -4 to -4.5 = 20/400 -5 to -5.5 = 20/600 -6 = 20/800 -7 = 20/1200 -8 = 20/1600 >-8 = cant even count fingers! comments: less than -1, also referred as "fractional myopia" is so slight, some still see 20/20. Near -1 may cost a line so 20/25(20/30 at worst) just shy of 20/20 in other words. -.25 or quarter diopter has never cost a line, often doesnt even make a difference from this optometrist's testing. He says -.5 diopters is usually the smallest where any blur can be percieved this is why you can often have a margin of error of plus/minus .25 diopter. *If you read my first post, I made my own diopter chart based on my research. The above is the research of one optometrist. It appears to go in line quite well with my own diopter chart. I do question if -6, -7, -8 or more is really that bad but since I have limited research in those high myopia dioptric values, I cant make any assertments till I research further. I have posted before wondering if my diopter chart begins to break down around -6 to -8 instead of keeps going on the linear/expotentional scale I have devised where 1.5x the diopters results in .5x visual accuracy. Here is a side by side comparsion to my diopter chart. My results are in (....) <-1 = 20/20 or just shy of 20/20(same) -1 = 20/40(same) -1.25 = 20/50(same) -1.5 = 20/60(same) -1.75 = 20/80(20/70) -2 = 20/100(20/80) -2.5 = 20/150(20/120) -3 = 20/200(20/150) -3.5 to -4 = 20/300(20/200 to 20/250) -4 to -4.5 = 20/400(20/250 to 20/300) -5 to -5.5 = 20/600(20/400) -6 = 20/800(20/500) -7 = 20/1200(just below 20/600) -8 = 20/1600(20/800) >-8 = cant even count fingers!(below 20/800) For the lower dioptric values, this optometrist's research concides/agrees with mine perfectly. For more moderate myopia values, he is a little more strict than me in his research on how well one can see. For high myopia -6 and up, our results are way different. I have limited knowlege of the visual accuracy of a high myope -6 or more and of someone with a visual accuracy worse than 20/400 since few charts go past that and none I know go past 20/800. I recall one optometrist who estimated this -11 lady at 20/3000 based on her counting fingers at a foot and a half(20/2667?) so I guess this -10.5 lady I chatted to(combined with slight astigmastim actually did have a -11 spherical equivalent) and this explains why she couldnt even count fingers at 2 feet! From her description how bad her vision was, she very well may have been 20/3000 or an order of more than 5x worse(now 7x due to my NVI) To attempt to record the results on an expotentional scale, up to -1.5 it appears to be linear. From the following values, I am recording the expotentional results. -1 to -1.5 = 1.5x diopters, 1.5x worse -1 to -2 = 2x diopters, 2.5x worse -1 to -2.5 = 2.5x diopters, 3.75x worse -1 to -3 = 3x diopters, 5x worse -1 to -4 = 4x diopters, 8x worse -1 to -6 = 6x diopters, 20x worse As you can see, the gap keeps growing between x(times) diopters and x(times) worse. -2 to -2.5 = 1.25x diopters, 1.5x worse -2 to -3 = 1.5x diopters, 2x worse -2 to -4 = 2x diopters, 3.5x worse -2 to -5 = 2.5x diopters, 5x worse -2 to -6 = 3x diopters, 8x worse -2 to -8 = 4x diopters, 16x worse As you can see again, the gap keeps growing between x(times) diopters and x(times) worse. Someone good at math would be able to estimate how high it goes from there and also graph it. My diopter chart has a linear component so it can easily be graphed. I will keep doing more research and even if I find that my origional diopter chart wasnt quite on the mark, I am leaving it there for simplicity and to show the results of earlier research and will attempt to make a 2nd, revised diopter chart that better reflects additional research. nondisclosed_email@example.com (Myope5)Sat, 29 Apr 2006 00:31:15 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p759,from=rss#post759https://bwelcometothevisionandeyeforums.runboard.com/p759,from=rss#post759my reply to him in another forum. While not diopters to 20/xx" it shows that very high myopia results in decreased BCVA as ive talked about in my previous posts >First off, I'll like to say thanks >for this forum. This is a >great source of information. You are welcome! >I'm very near sided (-16 and - >18) with someastigmatism (1.75 and 2.25). >I'm 41 years old,and started wearing >glasses at 4 years old. Ialso >started wearing hard contact lenses at >aboutthe same time. My corrected vision >has never been 20/20. The best >I've ever gotten is 20/40.I also >have very poor night vision. sorry to hear! If this makes you feel better, I also have never corrected to 20/20 even though my eyes arent as bad as yours. Ive been told my best corrected vision is seeing some of the 20/25 line and all of the 20/30 line. My pescription is in the -4 range. No one in my family can be corrected to a full 20/20 either, but all can to 20/25. 20/20 is perfect vision and very hard to achieve. >I've seen several optometrists and ophthalmologistsover the >years, and I have asked why >they can'tcorrect my vision to 20/20, >but never got a concise answer. >Some of the reasons suggested are: > I couldnt correct to 20/20 either and they said my astigmastim, high order aberrations and glasses minification all keep me from perfect 20/20 correctable. > * The brain/eye hardware for >vision forms >at a very young age. Since >I was probably >near sided from a very young >age (i.e. pre >4 years old), and was not >corrected initially, >my "hardware" isn't quite > right. sounds possible. Having never seen what good vision was like, you brain may have never developed percise vision. You never knew what it was like to see great. > * My eye ball is >not round, so the retina > is stretched, and as >a result there are > fewer light sensitive nerves per >square inch. This >results in a grainer picture > (like a low resolution >digital camera). another reason. Stretched retinas have other problems which disort vision. > * My night vision is >poor because the focal > point of the rods and >cones are different. >My corrected vision is based on >the cones (i.e. >daylight vision), so at night my > corrected vision doesn't >focus on the >rods (night vision). Thats in addition to your high order aberrations. > * My night vision is >poor because the optics > of my contact lenses become >incorrect as my >iris grows at night. Improperly focused > light comes in >at the edges of the contacts. > Do you see better at night with glasses? >Does anyone have any "insight" into this >issue? Your glasses minify so your 20/40 may be with RGP contacts while you may see 20/60 with glasses. >I'm also looking into the Verisyse IOL. >I've been told I would make >a good candidate. MyDoctor also thinks >that it may be possibleto get >better corrected vision with the IOL.Does >this sound realistic? >Thanks, >......Ken Id say 20/40 to 20/50 is relistic. Theres some risks with clear lens extraction but itll make your life much easier not to be blind without coke bottle glasses. You may still need a thin pair of bifocals for your astigmastim, any residual myopia and your presbyopia. this guy is -13.5 contacts(should be -17 glasses) he is losing tolerance to RGP contacts Dont you see much better with your RGP contacts vs. soft? 20/20 is very good vision(corrected, correctable), especially for an extremely high myope like you. I correct to 20/30 with my -4s glasses(due to high order aberrations) but if I ever tried RGP I probably will get 20/20. Youd be around a -17 in glasses! Do you even have an emergency backup glasses or ever wear them, maybe when you wake at night to eat a snack? anyway there are custom contacts that can be made to -20! another option is get the highest power in the brand you are most comfortable with then wear a thin pair of glasses over them to complete your pescription. I think this kinda sounds silly when there are contacts that fully correct you but some people can only tolerate certain brands and since their pescription is so high and rare, theres no market for companies to mass produce contacts this high. I see many companies go up to -10 or -12 in contacts. If you get a company that goes to -12 contacts, youd only need -2 glasses for the tiny remainder of your pescription. The good thing about this is you can take your -2 glasses off when reading or on the computer to relieve eyestrain and slow down your (pathalogical) myopia progression. (Otis will say stair-case) nondisclosed_email@example.com (Myope5)Mon, 03 Apr 2006 22:26:27 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p758,from=rss#post758https://bwelcometothevisionandeyeforums.runboard.com/p758,from=rss#post758"Although you may feel this way, you have a long way to go. My vision is much worse than yours (something like -12 the last time it was checked). I would not want to become much more nearsighted, because at some point they won't be able to correct it to 20/40, and I won't be able to drive." My comments: Glasses minification and especially very high myopia cause significent changes in the retina, thereby reducing BCVA. 20/30 BSCVA is average for -12 but if he has some extra high order aberrations, he may be getting 20/40 with glasses and if he gets more myopic, he may no longer pass the DMV. "Currently my eye sight is past 20/100. In my case, I have slight astigmatism Mine is at least -2.75 and still changing." My comments: With that pescription, its no supprise he can no longer see 20/100. He may be at 20/150 to 20/200 now depending on his astigmastim and BCVA. He probably has a spherical equivalent of -3 to -3.75 "I'm currently in 20/70. I started at 20/40. I feel that I'm nearly blind right now, I can not imagine becoming more nearsighted. My prescription right now is -1.75 in each eye. It use to be -1.00." My comments: That person is just a complainer. I am a good -4 and even I dont consider myself nearly blind at 20/400. I see great from 10 to 12 inches away uncorrected of course. I only correct to 20/30, that person should be thankful his/her UCVA and 20/20 BCVA is great. The diopters vs. 20/xx correlates perfectly with my research and further supports it. "I read the eye chart last week at a 20/60 in my right and 20/30 in my left. I asked for an interim script for glasses and feel much better now! Amazing how clear the world can be when fully corrected! I correct to 20/20 on my left and 20/25 on my right, with glasses! OD -3.00 +1.75 090 OS -1.75 +0.75 120" My comments: This translates to -1.25 -1.75(OD) and -1 -.75(OS) This is a spherical equivalent of just over -2 in the right eye so I am supprised hes seeing 20/60 with 20/25 BCVA. It would concide with my diopter chart if you ignored the astigmastim. The left eye likewise is also supprising. Maybe he squinted a little which skewed the results for both eyes? He wouldnt need glasses if he was really 20/30 in the better eye. I would expect 20/50 with that pescription and 20/20 BCVA. nondisclosed_email@example.com (Myope5)Thu, 16 Feb 2006 05:39:01 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p757,from=rss#post757https://bwelcometothevisionandeyeforums.runboard.com/p757,from=rss#post757While not diopters to 20/xxx, its about diopters to BCVA. I have mentioned this in part in my previous posts. The excerpt below shows how bad very high myopia is in both terms of 20/xxx and BCVA! "Luckily, I never did develop major retinal changes that we see in high myopes." This is why very high myopes(-10 and up) sometimes(fairly commonly) cant correct to 20/20 with contacts and even worse with spectacles(due to minification) One optometrist who posts on google groups said he sees patients around -15 diopters(myopia in the teens) with only 20/40 to 20/50 BSCVA. Looking at my notes, this guy whos -18 diopters can only correct to 20/60 with glasses. I know several more around -10 with 20/30 in glasses. One guy was -14 and 20/30 BSCVA, 20/25 with contacts which dont minify. ***additional comments*** in my previous posts, I mentioned diopters to BCVA in terms of averages. The correlation isnt as close as is the correlation between diopters and 20/something. -8 for 20/25 -12 for 20/30, -18 for 20/40, -27 for 20/60 are four examples for BSCVA. Hi, I'm 17. My perscription is -6.00 in 1 eye -6.50 in another, and -1.25 antagotism(sp) in 1 eye and 1.00 in the other. I believe I was 20/800 My comments: Hes correct about the 20/800 in the worse eye, were talking a spherical equivalent of -7 or just over that. The better eye would be -6.5 spherical equivalent and probably good enough to see a blurry 20/600 Thanks for the reply. With glasses my vision is:- PMT< -18.00/-2.00 DC X 170 -6/18 - NI -17.00 DS - 6/18 - NI Doctos have advised me to go for a LIO.I do not know what is it.Please tell me about it.Should I go for it or not.Is there any risks involved in it.And what is advisable. My comments: Due to his pathalogic myopia, hes experiencing retina problems including small holes and possible detachments. Spectacle minification also plays a role in addition to his pathalogic myopia which results in 20/60 BSCVA The nurse had my vision without my glasses on at 20/20 left eye, 20/15 minus three right eye, and 20/15 minus 1 with both eyes. My prescription is -.50(right) and -.75(left) My comments: I cant believe your optometrist pescribed you glasses and made you wear them even though you are 20/20 without them! Legal driving requirement is 20/40, you are well above that! Me thinks he just wanted to make a sale on glasses! I know of many cases like that, one guy was +.5 diopters and could see perfect from all distances(he was young too) and the optometrist still said he needs glasses. The parents took him to another optometrist who said dont even bother with glasses. I think you need another opinion. Wearing those glasses will just make your eyes worse than you wont be 20/20 without glasses anymore Man I am upset now, I cant believe some optometrists! ****************** Side by side comparsion(left)(rigt) *The most important chart* 20/40...........-.50 and -.25 20/50...........-.75 and -.50 20/60...........-1.00 and -.75 20/70...........-1.25 and -1.00* 20/80...........-1.25 and -1.00* 20/100..........-1.50 and -1.25 20/150..........-2.25 and -2.00 20/200..........-2.75 and -2.50 20/300..........-3.75 and -3.50 20/400..........-4.50 and -4.25 *20/70 or 20/80 is really almost the same. Sometimes I can see 20/70 at the same dioptric value as 20/80 depending how I interpret the blur and if I can get the eyes a little relaxed. Let me repeat this chart. As you can see, I am already 20/400 UCVA in the less myopic right eye and just shy of 20/400 in the left. Just .75 diopter additional improvement will get me 20/300 in the right eye. 1 to 1.25 diopter improvement will make the 20/300 considerabily easier to see. At the rate of my improvement, I should achieve another diopter improvement by the start of year 2007 and be 20/300 in at least one eye and possibily both! nondisclosed_email@example.com (Myope5)Sun, 05 Feb 2006 00:39:28 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p756,from=rss#post756https://bwelcometothevisionandeyeforums.runboard.com/p756,from=rss#post756 I found this image here! Note that if plano results in 20/15 for this particular person, he would be seeing 20/30 at -1, 20/60 at -2, and a little shy of 20/100 at -3. The simulated blur explains it all. My friend sees 20/60 at -2, 20/15 BCVA. See my diopter chart in the previous posts for details. So how good do I consider the following visual accuracies? 20/2=eagle vision. I highly doubt any human will see this good naturally. It may be possible with bionic eyes, genetic engineering to produce a mutant or perhaps remove a part of your retina and replace it with one of much higher density rods/cones. 20/3=Probably the very, very best a human will ever see naturally. May be the world record. Youd need to be a freak of nature with 1000% perfect eyes. 20/4=half eagle vision. The smallest line my printed snellen chart goes down. Its believed this is the ultimate limit of vision experts believe a human can ever have, hence thats the smallest line the snellen chart I found on the web to print has. You could make and print your own as small as capable of your printer. 20/5=hawk vision. Probably one in a billion humans see this good. Some experts dont even think a human can be capable of vision this good. 20/6=near hawk vision. The limit to human vision agreed by most experts. Some will argue humans may be capable of even better! 20/8=godly human vision and near the limits of human vision. Probably one in 5000 humans see this good 20/10=exceptionally good vision. I read that one in 1000 humans see this good, but I take the optometrist word that he says less than 2% see this good, its about 1% accroding to him. Thats 1 in 100! 20/13=very very good vision. Probably 1 in 15 humans see this good. 20/15=very good vision. Id estimate 1 in 4 humans see this good. 20/20=standard for normal vision. about 2/3 of humans see this good with or without correction. The rest see worse and not many see better. 20/25=still normal vision, very near "perfect" 20/30=very good vision 20/40=legal to drive anywhere 20/50=good vision, very rarely need glasses 20/70=fair vision, occasional need for glasses 20/100=minimum one can go without glasses and still see well enough 20/150=inadequate vision 20/200=legally blind if BCVA 20/300=bad vision 20/400=very bad vision 20/worse=functionally blind. Highly dependant on glasses nondisclosed_email@example.com (Myope5)Thu, 02 Feb 2006 22:49:14 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p755,from=rss#post755https://bwelcometothevisionandeyeforums.runboard.com/p755,from=rss#post755Bingo! I found a list of post-lasik patients, their pre-lasik diopters and UCVA and their post-lasik diopters and UCVA! Great for learning how diopters correlates to 20/xxx! I provided some links with my comments below the links! http://la-sight.com/LS_commDetail.asp?index=142 Isnt this nice shes still 20/20 at -.5 and 20/25 at -.75? I wouldnt be supprised if she corrects slightly better than 20/20! I woulda thought she should definately see 20/200 UCVA, especially in her left eye! http://la-sight.com/LS_commDetail.asp?index=141 Smart move correcting only one eye, the worse dormant one! His pre-lasik pescription does agree with the 20/400 UCVA, but might barely be 20/300 if he tried. http://la-sight.com/LS_commDetail.asp?index=140 Sorry but her vision is NOT bad and NOT 20/200. He probably told her she was 20/200 otherwise she would never have gotten lasik. My friend is also -2 and was told hes 20/100 but actually tested out at 20/60! He corrects to 20/15 with glasses and this goes perfectly with my diopters to 20/xxx http://la-sight.com/LS_commDetail.asp?index=138 20/30-(probably closer to 20/40) is not bad at all for being -1.25 diopters. Her -.25 eye is 20/20 and should be that way. Her results go in line with my diopter chart. I know -1.25 is generally 20/50 but she could correct to 20/20+ if plano. The evidence is shes still 20/20 at -.25! http://la-sight.com/LS_commDetail.asp?index=137 Isnt this funny the same pescription as the lady above only gets 20/70? I bet they try to inflate results both ways, make your pre-lasik UCVA sound worse than it is then make your post-lasik vision sound better than it is! She should likley be 20/50 at -1.25 if she corrects to 20/20. By the way why didnt she laser only one eye or leave things alone? What a waste of lasik as she will be back in glasses, the reading type that is in a few short years! http://la-sight.com/LS_commDetail.asp?index=136 Another diopter vs. 20/xx that doesnt match up. It would be in the ballpark for a 20/20 BCVA but since hes 20/15 he should be seeing better! Probably another example of inflating the results, make the pre-lasik UCVA as bad as possible http://la-sight.com/LS_commDetail.asp?index=135 Concides fine with my diopter chart. http://la-sight.com/LS_commDetail.asp?index=133 All her astigmastim must really blur things! She does have a spherical equivalent of -5.5 in the right eye, probably a little shy of 20/400. Wheres the 20/600 line? As for the -1 and 20/30, thats a darn good UCVA, probably slightly inflated by the surgeon to make it look good. http://la-sight.com/LS_commDetail.asp?index=132 Very strange. Thats a rather good UCVA for the diopters and astigmastim. He got lasik and an enhancement for nothing, his UCVA was more than enough to function without glasses for near and distance. Lasik actually *increased* his dependancy in glasses, now he needs readers! I pity him! Yes 20/15+ is good but his pre-lasik 20/20- is more than functional to see great uncorrected. http://la-sight.com/LS_commDetail.asp?index=130 -3.25 spherical equivalent, 20/15 after lasik. Should definately be 20/200 before lasik but I guess hes not good at interpretating astigmatic blur. http://la-sight.com/LS_commDetail.asp?index=129 sees 20/25 with -.5 sphere and cylindar. Does go in line with my dioptric chart that -.5 diopters costs one line. http://la-sight.com/LS_commDetail.asp?index=128 Goes in line for a 20/20 BCVA but should be seeing better than this. http://la-sight.com/LS_commDetail.asp?index=126 His left eye is -.5 and plano in the right and has the same UCVA in both? I guess his BCVA in the left may be a little better than 20/20! http://la-sight.com/LS_commDetail.asp?index=125 Ok this one makes perfect sense. -3.25 spherical equivalent for 20/200, corrected to 20/20 Read thru the rest. Isnt it funny almost everyone ends up with 20/20 and a third with 20/15? Many even have a tiny residual pescription such as -.25 or -.5 myopia and/or -.25 to -.75 astigmastim! Not enough to cost them a line. I dont know how they measure post-lasik vision but I bet theres lots of bias. Hey I was declared 20/20- when I went in for my lasik evaluation, the tech used the phororapter and "corrected" me to 20/20- If its like that for many people, then I know the truth! Most/many of them are a line(or two!) worse than they actually are! I even heard in a few centers, they cheat somewhat by moving the projector closer so every letter is like 20% larger. Suddenly your 20/20 is really only 20/24! Theres many other factors, see my thread here! http://com5.runboard.com/bwelcometothevisionandeyeforums.flasereyesurgery.t42 Anyway to conclude diopters to 20/xxx half the results are right on the money, the other 25% are in the ballpark and the last 25% are way off! Perhaps some people are unwilling to make any effort to interpret the blur and just say "I cant see, I cant see!!!!!!!" or maybe they "miss" on purpose to gain symphathy. Or perhaps they are straining so hard, things instantly become alot blurrier. I have researched my own results and I can tell you right now that -2 is MUCH better than 20/200. I only correct to 20/30 in the better left eye and with a -2 undercorrection, 20/200 is not even an effort to see. Its a little blurry but no straining or interpretation needed, its clear enough to readily be seen. Even 20/150 is not much of a problem! Those who correct very nicely, such as a true 20/15 will see 20/60 or 20/50 to 20/70 with a -2 pescription! See my diopter chart in the previous posts, youll see! The 50% of the results that are on the money concide with my diopter chart. Those people are seeing 20/200 in the -3 range and 20/400 in the mid -4 to -5 range! They see better than 20/200 with mild myopia of less than -3! One guy was 20/100 at -2.75, corrects to 20/15, another 20/80 at -2.25, a third still was 20/70 at -2! I stand by my diopter chart research, although I admit I am a bit uncertain about the correlation if you are a high myope(-6 or more) because I havent done extensive research on this. Read my earlier posts for further comments reguarding this. nondisclosed_email@example.com (Myope5)Fri, 27 Jan 2006 12:35:36 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p754,from=rss#post754https://bwelcometothevisionandeyeforums.runboard.com/p754,from=rss#post754***My results with left eye*** plano to -.25...........20/30 -.50 diopters...........20/40 -.75 diopters...........20/50 -1.00 diopters..........20/60 -1.25 diopters..........20/70-80 -1.50 diopters..........20/100 -2.25 diopters..........20/150 -2.75 diopters..........20/200 -3.75 diopters..........20/300 -4.50 diopters..........20/400 -4.50 diopters, -.75a...20/500 *20/70 and 20/80 are nearly the same size making the difference insufficent ***My results with right eye*** plano to -.25...........20/40 -.50 diopters...........20/50 -.75 diopters...........20/60 -1.00 diopters..........20/70-80 -1.25 diopters..........20/100 -2.00 diopters..........20/150 -2.50 diopters..........20/200 -3.50 diopters..........20/300 -3.50 diopters, -1.5a...20/400 *20/70 and 20/80 are nearly the same size making the difference insufficent Side by side comparsion(left)(rigt) plano to -.25...........20/30 and 20/40 -.50 diopters...........20/40 and 20/50 -.75 diopters...........20/50 and 20/60 -1.00 diopters..........20/60 and 20/70 -1.25 diopters..........20/70 and 20/80 Side by side comparsion(left)(rigt) The most important chart 20/40...........-.50 and -.25 20/50...........-.75 and -.50 20/60...........-1.00 and -.75 20/70...........-1.25 and -1.00* 20/80...........-1.25 and -1.00* 20/100..........-1.50 and -1.25 20/150..........-2.25 and -2.00 20/200..........-2.75 and -2.50 20/300..........-3.75 and -3.50 20/400..........-4.50 and -4.25 *20/70 or 20/80 is really almost the same. Sometimes I can see 20/70 at the same dioptric value as 20/80 depending how I interpret the blur and if I can get the eyes a little relaxed. There probably shouldnt even be a 20/70 line. On my dioptric chart in the first post, I put down -1.75 for 20/70 and -2 for 20/80. There is a difference but its slight and could go either way. A tired -1.75 may not bother focusing and see 20/80 while an alert -2 may strain to see 20/70. Basically my right eye is about .25 diopters worse but not due to myopia, but irregular astigmastim which blurs as much as an additional .25 diopters in my left eye. My right eye has a BCVA of one line worse so the same diopters gives me worse vision in the right eye. There is a big difference between BCVA and your UCVA with a given dioptric value. The reason for this is complex and irregular astigmastim as well as high order aberrations also factor in the blur. Uncorrected astigmastim of any kind costs lines. If I leave my -.75 astigmastim in the left eye uncorrected, it costs me one line. Irregular, complex astigmastim cant fully be corrected. You can approximate it in two ways, spherical equivalent and a "best fit" approximation using regular astigmatic lenses. See my previous posts for more explanations on BCVA, myopia and astigmastim. I have about a diopter and a half of irregular astigmastim in the right eye. Spherical equivalent will get me to 20/40 with -4.5 diopters but letters are fuzzy and doubled. A -5 lens reduces more of the doubling but does nothing to improve the fuziness and also hurts my eye as its too strong. Using a -1.5 cylindar lens is much more accuate but since my astigmastim is assymetrical and irregular, it doesnt get corrected exactly, just approximated. Its like making an approximate sized round peg to fit in a square slot or vice versa. I tried all combos and the best is -3.5 sphere and -1.5 cylindar. Optometrists generally like to go for spherical equivalent because its quick and easy. Mine always did that, especially in the right eye. The end result may be the same, but the quality of vision is NOT as good despite identical or one line less BCVA. I see 20/40 in the right eye with -4.5 sphere or -3.5 sphere+-1.5 cylindar but the quality of vision is better and theres none of the doubling that I see with the spherical equivalent. I would not reccomend spherical equivalent if more than -1 astigmastim when wearing contacts. I know this guy who sees 20/20 with glasses, 20/30 with contacts because his astigmastim may be like -2 diopters so they overcorrect him in one mederian by +1 diopters and undercorrect him in the other by -1. They cancel out, but results in blur. Hence his loss of two lines with contacts. My snellen results are fairly accurate but some outside factors such as lighting and blur peception may slightly influence results. However the correlation follows a very close curve, generally within plus/minus a quarter diopter. I took the middle when reporting my results. My testing was done in a darkened kitchen with the hallway light illuminating the snellen chart and I look 20 feet down the hallway. This eliminates any pinhole effect due to constricted pupils. On the other end of the kitchen looking in the opposite hallway where the lights are brighter in addition to the bright lights in the dinning room, I can make out the same line with an additional ~half diopter more myopia. All diopter to 20/xx values are taken in room light which is fairly dim. Stay away from windows where the bright sun streams in or better yet do it at night like I did. Do make sure theres plenty of light illuminating the snellen chart but you dont want lots of light shining directly in your eyes! Someone with a BCVA of 20/20 is of course going to see more lines with the same diopters as I will because I have astigmastim and high order aberrations contrubating to the blur. Some dont understand and think they should all see the same and that it doesnt matter. They couldnt be more wrong. Take my 20/40 BCVA in the right eye. I may have corrected myself to plano but I am still experiencing blur due to what glasses CANT correct. I can only correct all of my myopia and some of my astigmastims. Take another guy with 20/40 UCVA. If the reason he is 20/40 because of myopia, then glasses will improve his vision. If most of his 20/40 vision is due to astigmastim and high order aberrations, then only a small remainder is due to myopia. He may correct to 20/30 with a -.5 lens. The astigmastim and high order aberrations that dont get correct prevent him from seeing better than 20/30. There are a modest number of people that correct to 20/15, they have very few high order aberrations and better than normal optics. If a such person is seeing 20/40 UCVA, he may have -1.5 diopters of myopia. Instead of myopia, I have irregular astigmastims and high order aberrations. We are just starting to develop technology to address those compound refractive issues. Defocus such as myopia and hyperopia is the easiest and was the first sort of correction to be invented some 700 years ago. Astigmastim is about 180 years old, having been invented in 1825! Check this article! Great read!!!!!!! We are now in the process of inventing wavefront glasses to further "fine tune" vision to beyond 20/20! High order aberrations is far more complex than your simple refractive error. Much is still being researched on this but imagine 20/10 being the new standard instead of 20/20! Two 20/40 guys may have different pescriptions, one could be -1.5 with few aberrations, the other -.5 with more aberrations! Lastly, I posted this before but now that I have a trial lens kit for my testing purposes, I can much more accurately test my diopters to 20/xxx The results for each eye are with the astigmastim already compenstated for. This isolates myopia as the only varable. The values shown are with me undercorrecting myself in diopters and their corresponding visual accuracies I achieve. For example, a -.25 diopter undercorrection does not cost me a line but does make the existing BCVA line blurry but still visable. The bottom line of my results shows my visual accuracy without correction. I can barely see 20/400 UCVA in the less myopic right eye. Why am I doing all this? Its fun and research and good record keeping to track my progress of vision improvement! Some people keep records of their weight loss, I keep records of my myopia loss nondisclosed_email@example.com (Myope5)Wed, 25 Jan 2006 03:15:43 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p753,from=rss#post753https://bwelcometothevisionandeyeforums.runboard.com/p753,from=rss#post753The below is a repost in another thread but its fitting to be posted here too This is a similar example. The E is 20/400 then the W is probably 20/300(this one pictured doesnt have a 20/300 but some do) Next down is probably a 20/200 E. I believe theres 20/100, 20/70, 20/50, etc. Not sure if theres a 20/80, 20/150 but some projection charts have those too. NOTE The exact example I saw when I got my eye exam is shown below! This is probably one of the more common ones. Notice the 20/400 E, the 20/300 W, the 20/200 E? Half the projector slides have this part. I have put the dioptric values. See my other thread to read all about it. The following lines are as: 20/400(-5.25) 20/300(-4.50) 20/200(-3.50) 20/100(-2.25) 20/80(-2.00) 20/70(-1.75) 20/60(-1.50) 20/50(-1.25) 20/40(-1.00) 20/30(-.75) 20/25(-.50) 20/20(plano to -.25) 20/15(rare) 20/10(very rare) There really should be a 20/150(or 20/160) line! There also should be a 20/13(or 20/12) line as well! I guess they dont consider it very important past 20/100 since your already seeing bad anyway and need correction at this point. nondisclosed_email@example.com (Myope5)Fri, 20 Jan 2006 09:20:38 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p752,from=rss#post752https://bwelcometothevisionandeyeforums.runboard.com/p752,from=rss#post752My pre-op Rx and post-op results are:            OS (left) OD (right) Pre-op -9.00 sph +1.00 cyl -8.75 sph +1.75 cyl 2 weeks post-op -2.25 sph 0 cyl -1.75 sph 0 cyl 6 weeks post-op -3.25 sph 0 cyl -2.75 sph 0 cyl The surgery only took about 10 minutes and was relatively painless. The worst part was when they examine the cornea afterword with a VERY BRIGHT light. You can't blink and the light is painfully bright, but it doesn't last too long. The days and hours of anxious waiting before the surgery is far worse than the actual procedure. I had absolutely no post-op discomfort and haven't since, except for an occasional dry burning sensation that goes away with eye drops. As you can see from my results, I didn't get 20/20 vision on the first try. I saw 20/70 the next day and have slowly regressed to about 20/100 or so. Note to all you high myopes: 20/70 is damn good compared to whatever we are at -9 or worse! Before, I couldn't read the big E on the eye chart. Now, even with -3 d of nearsightness I can function without glasses, which is something I could not do before, so it is a big improvement. My comments: Hes giving the correlation between diopters and 20/xxx notice hes seeing 20/70, presumbly with the better -1.75 eye. Also notice he regressed to 20/100 then a little worse, perhaps 20/150 at -2.75 also notice at -9 theres no way he will see any snellen eyechart letters not even the 20/800 E! -3 is a very, very big improvement when you used to be a -9! Hes probably going to leave things well enough alone and not go for a lasik enhancement due to his presbyopia and keeping his near vision intact. Its not as much improvement for me where im a -4.5 and using a -1.5 trial lens gets me down to -3 but enough improvement to be noticable but not quite enough to go "wow!" Give me a -3 trial lens and were talking a significent improvement and I wish I were only -1.5 diopters! This would be good enough to almost never need distance glasses, yet not need reading glasses except for fine print. Overall it was a good experience, but there was a complication with epithelial depletion during the procedure causing extended healing time and pain, and there seems to be 2.0 diopters of astigmatism caused by the surgery in the right eye. I am a good 20/20 in the left eye, and a bad, blurry 20/25 in the right eye, from my -7 to -8D pre-op prescription. My comments: -2 diopters of astigmastim is like -1 diopter spherical equivalent It is somewhat supprising to still see any of 20/25 with this much astigmastim or this much myopia unless your BCVA is better than 20/20 "The vision was good, 20/25 unaided in that eye, correctable to 20/20 with -.50" My comments: aha! Diopters to 20/something revealed! This confirms that -.5 diopters indeed does only cost one line of vision and is such a low refractive error its not really myopia in the sense that its a problem, per see. I consider low myopia -.75 to -2.75 and many agree with this. When my post-op was -.25 and -.50 I was still 20/20. My comments: I would not be supprised if a -.5 lens allowed him to see at least some of the 20/15 line. I just happened to be reading a book this morning, and came across a table listing the relationship between refraction and acuity. (The book is called The Laser Vision Breakthrough, and it said the table should only be considered a rough guide. BTW - you'll learn alot about refractive eye surgeries from the book, although my feeling is that it emphasizes the positive aspects and sugar-coats the potential negatives) The number to the left of the = sign is the spherical measurement. No or minimal refractive error     0.0 = 20/20(normal BCVA)     -0.50 = 20/30(20/25) Low myopia     -1.0 = 20/50(20/40)     -2.0 = 20/150(20/80)     -3.0 = 20/250(20/150)     -4.0 = 20/400(20/250) Moderate myopia     -5.0 = 20/500(20/400)     -6.0 = 20/650(20/500)     -7.0 = 20/800(close enough) Extreme myopia     -8.0 = 20/1000(20/800?)     -9.0 = 20/1300(20/1000?) Cant be really sure on the two above, but I am just going by my diopter chart formula but the formula may break down somewhere here. My comments: I dont agree with some of them but for the higher pescriptions, the conversion doesnt seem too far off. Since few people are high myopes and since most eyecharts max out at 20/400 "E" its difficult and tricky to measure higher. I have extensive research on lower myopia. The pranthesis is my research results. They are somewhat too generous, especially in the lower myopia range. I was close to your prescription. I had about 12 diopters (nearsightedness) in each eye with an additional 3 diopters of astigmitism in each eye. My corrected vision with contacts was no better that 20/25. I also needed reading glasses (I'm 57). My comments: Although not diopters to 20/20, this goes in agreement with my chart stating diopters to BCVA. 20/25 BCVA with contacts is not unusual for very high myopia. Extremely high myopes may have even worse BCVA Your OD did a disservice by reccomending full time glasses wear. A low myope does NOT need glasses for close work, actually the opposite is true, he should NOT wear glasses for near, it will do nothing but cause eyestrain. Nearsighted means one can see great from near, so no glasses to be worn for near. The ODs here already said not to worry about lazy eye. You and your son can take measures to greatly slow the progression of myopia. Otis firmly believes in the plus lens theory to stop and even reverse the progression of myopia. An 8 year old probably doesnt want to bother with reading glasses when he sees fine from near. The next best thing to do is have him hold reading materials away from him and not 6 inches close like some people like to read at! Have him take frequent breaks looking off into the distance after doing prolonged near work. Keep him off the "evil" minus lens as long as possible and as long as he can see well without them. Once he can no longer see clearly without minus lens, wear glasses only for distance such as seeing the board in school or watching TV. Never wear glasses for near work. "*If* there's anything you can do to slow the process, wean him from reading and working very close ("nose in the book") and make sure he gets occasional "far-vision" breaks while doing close work." Good advice. "After reading a bit in this group about Diopters vs. 20/xx I'm a bit confused with the perscription I was given for my 8yr old ( see below ) R: -1.50 ( 20/100 vision uncorrected ) L: -0.75 ( 20/30 vision uncorrected ) To me it seems like a -0.75 is a very strong perscription for a child with 20/30 vision. I also had him try reading a snellen eye chart and came up with more like ( R: 20/50 L: 20/30 )." -.75 is right on the money to bring 20/30 back to 20/20. Weaker glasses wouldnt correct him to 20/20 There is no way he is 20/100 with only -1.5 diopters. Your testing him at 20/50 is more like it. Heck even I used to see 20/70 or 20/80 years back when I was -1.5 and I was only corrected to 20/25. Some optometrists dont know how to properly measure one's vision. I was proclaimed 20/20 before even though I guessed ONE letter right on the 20/20 line with correction. "That's the problem trying to predict diopters from snellen acuity. Half the time it's in the ballpark, the other half it's misleading." actually, it should be in the ballpark all the time or something is wrong. Over 95% of people who post their pescription and UCVA fall in the ballpark. There is this one guy who was seeing only 20/60 with -.75 pescription, correctable to 20/20+ with glasses. He got lasik and is now -.5 after 6 months and sees 20/20. We went by the theory he was straining his eyes without glasses, resulting in tonic accomodation and hence increased blur. Glasses relaxed his eyes and tonic accomodation went away. I have done much research on the correlation of diopters to 20/xxx and for lower pescriptions, its much more predictable than for high pescriptions. Take a -1 for example, results typically in 20/40 UCVA. Take -4.5 or -5.5, both can still be 20/400 but the -5.5 would see a much blurrier 20/400. "-0.75 isn't a "very strong perscription" no matter who has it." Very weak pescription. Most people who get glasses for the first time are higher than -.75 and the vast majority of -1 and under rarely or never wear glasses. "I was just trying to verify that 0.75 is not an overcorrection for 20/30 vision" If he corrects to 20/20, -.75 is right on the money. "Wrong, ace, 20/30 is about right for -.75. If anything, I'd guess 20/30 is more like -1.00." I am in agreement with this. I even have a thread on ***Diopters to 20/something conversion. The math and science behind this!*** Very interesting thread and I learned more about diopters to 20/xxx as well!!!!!!!! nondisclosed_email@example.com (Myope5)Tue, 17 Jan 2006 03:49:21 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p751,from=rss#post751https://bwelcometothevisionandeyeforums.runboard.com/p751,from=rss#post751Hello everyone, post your dioptric pescription(how bad are your eyes), your UCVA(uncorrected) and BSCVA(corrected by glasses) Also if you know anyone's vision, post that too. I have done much research on the correlation of diopters and 20/xxx and have compiled several charts, formulae, tables and comments on the results obtained thus far. To test for this, do it in room light or dim light. Make sure the eyechart is well illuminated and your not squinting at all or recalling from memory or guessing. Blur preception is of course allowed. I and most optometrists have found that -.25 diopters doesnt cost you a single line but makes the existing line blurry but still readable. Some say it costs half a line. Such as if you can see half of 20/15 with a -.25 lens, youll be a full 20/20 but wont be able to see better than that uncorrected. Another example is if your seeing all of 20/20, you may miss half of the 20/20 with -.25 diopters. Others have said it didnt affect their ability to read a line, just made it harder to do so. Minus half diopter(-.5) is generally accepted as resulting in one full line loss. This means 20/15 becomes 20/20 and 20/20 becomes 20/25. If you can see half of 20/15 youll be seeing half of 20/20. Minus one diopter(-1) generally gives you half visual accuracy. My friends who see 20/20 with glasses see 20/40 without their -1 glasses. Ditto for 20/15 with -1, 20/30 uncorrected. I was 20/50 corrected to 20/25 with a -1 lens years ago. Higher dioptric values become harder to calculate and predict, especially when you get to -6 and up. Someone could be -4.5 another -5.25 and both see 20/400 UCVA. The -5.25 probably will see a much blurrier 20/400 than the -4.5 but generally, 20/400 represents a moderate of myopia around -5 diopters. One website said the range was -4 to -6 for 20/400 and your best corrected vision played a big factor. Someone whos 20/15 corrected needs more diopters to see the same blur as another with 20/30 corrected. For me, my left eye at -5 or so couldnt see 20/400 while my right eye at -4.5 or so just barely, barely saw 20/400. I know two people who passed V3 requirement which states you have to be 20/400 or better uncorrected and both were barely 20/400 with -5.5 pescriptions with 20/15 corrected. Those two guys said they dont know anyone else -5.5 or more who passed V3 which requires 20/400. They probably didnt have the great 20/15 corrected vision with glasses so for them, -5 was the limit(20/20 corrected) I am not correctable to 20/20 so my limit is even less. Few eyecharts go beyond 20/400 so info is scarce past this. I have a solid grasp on dioptric values below -6(mild to moderate myopia), but for -6 and up which is high myopia I am less certain how this converts to diopters. I do know high myopes are worse than 20/400 but how bad exactly? Also theres much fewer high myopes than low and moderate myopes so much of my info is on low(er) myopes and their diopters to snellen accuracy. One could stand closer but then accomodation needs to be taken into account. I can see the 20/200 E from 10 feet less blurry than the 20/400 E from 20 feet. At 5 feet I see the 20/70 line but im certainly worse than 20/280. I experienced .67 diopter accomodation from the 5 feet mark. If any of you have charts and formulae, on what expotentional scale does this equal to? I know that going from -1 to -2 is only twice as bad(20/40 and 20/80), but going from -3 to -6 is definately more than twice as bad(20/150 and 20/500?), blurs much more than twice. Does this gap become even larger still at -6 to -12(20/500? and 20/????) where the number of times more blurry increases expotentionally? Me and many others are curious about this and this topic has been posted before many years ago. Its also useful for some occupations such as pilot, soldier, law enforcement, etc where they have a requirement for both corrected(BCVA) and uncorrected(UCVA) vision and people ask all the time if their UCVA is good enough to make the cut. nondisclosed_email@example.com (Myope5)Tue, 10 Jan 2006 06:13:47 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p750,from=rss#post750https://bwelcometothevisionandeyeforums.runboard.com/p750,from=rss#post750Countinued from post above Ok thats it for 25 cases. I may update with more cases in a new post. Below presents my summary which is reprensative for nearly everyone correctable to 20/20. diopters to 20/something less than -1........20/20 to 20/30 -1........20/30 to 20/40 -1.5........20/40 to 20/70 -2........20/70 to 20/100 -2.5........20/100 to 20/150 -3........20/150 to 20/200 -4........20/200 to 20/300 -5........20/400 20/something to diopters 20/30........less than -1 20/40........-1 to -1.25 20/50........-1.25 to -1.5 20/70........-1.5 to -2 20/100........-2 to -2.5 20/150........-2.5 to -3.25 20/200........-3.25 to -4 20/300........-4 to -4.75 20/400........-4.75 to -5.5 20/something representating dioptric range extremes, this takes into account BCVA no worse than 20/25 and as good as 20/10 or even better! 20/25........plano to -1.75 20/30........-.25 to -2.25 20/40........-.5 to -2.5 20/50........-.75 to -3 20/70........-1 to -3.5 20/100........-1.5 to -4 I am not exactly sure on the upper end extremes because BCVA of 20/10 or even better is very, very rare(less than 2% get 20/10). I have heard claims of 20/20 with -1 a few times however. They were correctable better than 20/15 of course. Then theres the -2 diopter claims of 20/40 and I even heard one 20/30 claim!(he was correctable better than 20/10 is all thats known) Ive heard plenty of 20/100 claims with -3, all correctable better than 20/20 of course. Many were 20/15 I believe. I even heard one claim of 20/70 with -3, correctable to a full 20/10! I will repeat(from a previous post here) what one optometrist said in a message board reguarding 20/something and diopters. Optometrist: This is the UCVA our patients get with the following pescriptions -1 20/30 to 20/40 -2 20/70 to 20/80 -3 20/100 to 20/200   The amount of minification(or magnification) is 2% per diopter. My -5 glasses minify 10% which is enough to be noticable, everything I see is a little smaller than normal. Many things are too small for me to see without getting closer. High myopes experience significent minification and can often result in costing them one or more lines as ive explained in my previous posts. Take an emmetrope and a -12.5 myope. The 20/25 line a -12.5 myope sees is minified 25%(2% per diopter) so therefore the 20/25 line for this -12.5 myope with glasses is minified so its equal to the size of the 20/20 line an emmetrope sees. Both have true 20/20 vision, the -12.5 myope has 20/25 BSCVA, however if he wears contacts, he would have 20/20 BCVA. Notice the 20/20 line and 20/25 line are the same size! With glasses the 20/25 line is the same size as the 20/20 line he sees with contacts! The eyechart an emmetrope sees or someone with a refractive error using contacts. Eyechart minified by 25%(to do the math, divide by 1.25 or multiply by .8) Notice that the 20/25 line is now the same size as the 20/20 line in the non-minified chart above! nondisclosed_email@example.com (Myope5)Sat, 31 Dec 2005 16:20:40 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p749,from=rss#post749https://bwelcometothevisionandeyeforums.runboard.com/p749,from=rss#post749The above post(about the -9) is a countinuation from the bottom post on page 3. I will be adding more case examples and my comments: Case example 1: My eyesight is 20/400 -5.25 diopter with a slight astigmatism (pretty dadgum bad). My comment: This just barely agrees with my diopter chart. However with the astigmastim factored in, he would need to perhaps be 20/15 BCVA to just barely pass 20/400 uncorrected with this pescription. Case example 2: I made the 20/20 cut but by my NAMI physical in Pensacola the next year, I was at 20/30 (probably stressed a bit as well). Luckily the cut was then 20/30 correctable to 20/20. From 93 to about 00, my eyes slowly became worse until they bottomed out at 20/80 (-2.00 as I recall). I then had PRK in 03 and my eyes have been perfect sense. I've got 20/12.5 vision in both eyes My comment: I would think hed be seeing closer to 20/60 if he could be corrected better than 20/20 with glasses and with PRK. I bet he must of had a little astigmastim or perhaps been closer to -2.5 but didnt exactly remember. However -2 and 20/80 does agree with my diopter chart for 20/20 BCVA Case example 3: I have an issue with astigmatism -4.75 my vision is 20/50 both eyes. My comment: That would be near -2.5 diopters spherical equivalent. I highly doubt someone with this much astigmastim can see 20/50 Perhaps his other eye is less astigmatic since he mentioned both eyes so the 20/50 is the better eye doing the work? Case example 4: It's hard for me to believe that you can read the 20/40 line with an astigmatism or -4.00. you are correct in the fact that because my astigmatism is what it is my vision should be alot worse than what it is, this is the same reply that I have received from so many docters. My comment: Again this is hard to believe. Thats a spherical equivalent of -2 myopia Case example 5: Anyway, my eyes were 20/400 and -4.75 diopters in both eyes before the surgery. My comment: Makes perfect sense. I am -4.5 in the right eye and can just barely see 20/400, the left at -5 cant. Case example 6: I want to apply for SNA but my uncorrected vision is 20/400 and -4.75 diopters. My comment: same as above. Another example. Case example 7: I had it done in September, my vision was 20/400, (-4.5 diopters). My comment: pretty much the same as the two above. I do believe he may have just barely been able to see 20/300 if there was a 20/300 line on the snellen chart he was being tested on. Case example 8: I am not sure what the 20/xxx was before surgery, I just know that I was -7.25 and -6.5. I'm sure its somewhere around 20/600 or worse My comment: This makes sense. Accroding to my diopter chart, he would have a hard time seeing 20/600 in the better eye and his worse eye would likley be closer to 20/800. Sucks being a high myope. Case example 9: Diopters are now -4.00 and -3.25. About 20/200 uncorrected, but I correct to 20/20. My comment: This sounds right for the -3.25 eye. I doubt his -4 eye is going to be able to see 20/200. With both eyes of course he can see 20/200 because the better eye will be doing the work. Case example 10: +/- 8 is greater then 20/100... and i'm -3 and i'm WAY past 20/100 and got in. My comment: This makes sense. Not too many people will see 20/100 at -3. This pescription is generally accepted to be closer to 20/200. Case example 11: I had -1.75 with an astigmatism, that gave me around 20/45 vision, had PRK, now I see alittle better than 20/15 My comment: Since hes correctable to at least 20/15, his visual accuracy is in line with his pescription. Case example 12: Ok I had a 1.25 diopter in left eye with 20/80 vision, and just under 1 diopter in right eye with 20/40. granted my eyes were not that bad i got the surgery with 20/15 results My comment: He must of had some astigmastim as well, especially in the left eye. An extra 1/4 diopter myopia is NOT going to take you down to 20/80 from 20/40 Case example 13: Some more details for those interested: My refractive error was measured at MEPS as -4.00/-4.25 (left/right eye) and during my flight physical as -4.00/-4.00. My distant uncorrected vision was 20/400 (i.e., I couldn't read the 20/200 line). With glasses, I correct to 20/20. My comment: If his eyechart had a 20/300 line he would definately see that. I am not supprised he cant see 20/200, but perhaps he could if he was correctable to 20/15 Case example 14: The astigmatism is now -1.00 in the L, and -1.50 in the right. I was told as the AK's gradually settle further over the next several months I can expect further minor improvement. ) Snellen acuity for L is 20/20- (just short of 20/20, and I don't understand this), and the R is 20/25 and is more likely to improve further. My comment: With his mild astigmastim, it makes sense hes 20/25, the left being better obviously due to less astigmastim. Case example 15: at -1.5 diopters and 20/60, get to 20/20 by looking through a negative lens My comment: Makes perfect sense accroding to my diopter chart. This is right on! Case example 16: I'm not familiar with prescriptions other than I have -6.00 (yup...20/500 over here). My comment: This one also makes perfect sense. With this pescription, he would barely see 20/500. Since most eyecharts dont have a 20/500 line, he could be considered 20/600. Case example 17: I'm no eye doc, but -3.50/-4.25 is WAY worse than 20/40. My contacts are -2.00 and my vision is ~20/100. My comment: Thats correct. I would be considering him 20/200 to 20/300 with his pescription, the better eye being barely 20/200 and the worse eye at 20/300. As to the -2 contact lense guy, thats equal to -2.5 glasses unless hes being overcorrected with his contacts. This does correspond to 20/100 or therebouts. Case example 18: My vision is approximately 20/75 My diopter measurements are -2.25 My comment: Not a bad acuracy for this diopters. Never seen a 20/75 line, so well say hes 20/70. Hes probably correctable to 20/15 in order to be 20/70 at -2.25 Case example 19: Ace, I looked at my last pair of prescription contacts and they read a -2.00 prescription. Does this make more sense regarding my 20/80 distance vision without glasses? I correct to 20/15 My comment: Due to vertex distance, he should be a -2.5 in glasses. His example concides perfectly with my diopter chart. 20/15 BCVA, 20/80 at -2.5(20/80 at -2 if 20/20 BCVA) Case example 20: I requested to be left slightly myopic to keep me out of readers till my late 40s. My distant vision is 20/20 in normal lighting, but drops to about 20/30 in dim light. So I keep a pair of -0.75 specs in the car that I use only rarely during night driving My comment: This concides perfectly with my diopter chart. The 20/20 is due to pinhole effect or correction at -.75 diopters. Case example 21: I have begun CRT about 1 week ago. Here is my data: Initial refraction -3.50-1.50x010 OD, -4.50-1.00x170 OS. After 1 week overnight wear I am -0.25-0.50x180 OD, -0.25DS OD with 20/20 OD, 20/20 OS uncorrected. My comment: -.25 diopters may make the 20/20 line a little blurry but this is so little "myopia" it should not cost any lines. One optometrist even stated that hes never had a patient lose a line with a -.25 refractive error. Case example 22: I am a 28 years age and 10 years ago I underwent Ortho-K treatment. Back then I had 20/60 vision in both eyes. My optometrist promised me at least 20/20. I got it. However, 10 years later, I now have 20/160 with -2.25 in both eyes. My comment: This is below the 20/100 he "should" see but perhaps he has a bit of astigmastim or isnt fully correctable to 20/20 but can see some of it. Case example 23: Following cataract surgery in the OS, I have 20/40 vision in that eye although it can be improved to 20/20 with a -1D lens. My comment: makes perfect sense. -1 reduces his vision by half Case example 24: Actually my prescription is -3.00 about in each eye. At twenty feet the OD says I can only see 20/160, 20/200. After resting I could probably see about 20/100, or 20/70 or so. My comment: A -3 refractive error does correlate to 20/150 on my diopter chart but some charts have 20/160 instead. Close enough I guess and I bet he could easily see 20/150 if not better with a little resting like he stated. Case example 25: 2/27/98: I had my one month exam yesterday. My left eye is still plano. My right eye has 1/2 diopter myopia with approximately 1/2 diopter astigmatism. My co-managing doctor told me I have 20/25 vision <grin>. My comment: Makes sense. Half diopter reduces your BCVA by one line. Ok thats it for 25 cases. I may update with more cases in a new post. Below presents my summary: nondisclosed_email@example.com (Myope5)Sat, 24 Dec 2005 07:30:09 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p748,from=rss#post748https://bwelcometothevisionandeyeforums.runboard.com/p748,from=rss#post748B. -9.00 .... 20/1000 I have no experience here other than my simulation. I did wear one +3.5 glasses over my -5 eye to simulate -8.5 and was seeing 16/800 which is basically 20/1000 and compenstating for magnification, its 20/1070 at -8.5 and a solid 20/30 BCVA. I tried again and came up with 20/1140 this time compenstating for magnification and all and 15/800 which I could see clear enough for 80-90% accuracy. I am just going to say I very highly doubt anyones gonna be seeing 20/800 with -9 and in fact its safe to say youd be perhaps 20/1200, definately no better than 20/1000! I am stopping here as its moot offering baseless explanations for higher than -9. You may see the 20/xxx for higher in my first post but its based only on my formula and I honestly dont know if the formula is this linear. You can clearly see the pattern where each 1.5x increase in myopia results in a .5x accuracy. This formula starts at 20/100 and keeps going on. Does it end somewhere before that? At 20/400? 20/600? 20/800? Whats the new formula after this, on what expotentional scale? nondisclosed_email@example.com (Myope5)Fri, 23 Dec 2005 15:34:45 +0000 Re: So how bad is -1 diopters? -2? -10? My eyechart research!https://bwelcometothevisionandeyeforums.runboard.com/p747,from=rss#post747https://bwelcometothevisionandeyeforums.runboard.com/p747,from=rss#post747Theres some controversity reguarding the rules of vision accuracy. Its widely accepted you need to see a majority of the letters without randomly guessing and getting lucky. The more letters of a given line you have the subject read, the more reliable your results will be. I say 10 is a good minimum number of test letters where you need to get more than 2/3 right so thats 7 out of 10 to "pass". However getting all 10 right is certainly better. Someone seeing a solid 100% 20/20 is certainly better than someone barely seeing/guessing and getting slightly more than 2/3 of the line right. However both have very good vision and the differences is in reality very small, perhaps on the order of 20/20 vs. 20/21 or 20/22. I have stated that the following values are if your correctable to 20/20(compenstating for minification) If you can see more than 2/3 of 20/20, its enough to count and close enough to be within my diopter chart guidelines. Someone seeing 100% 20/20 and another guy seeing 70% of 20/20 are both close enough to for example be 20/100 at -2.25 however someone only seeing 1/3 or 1/2 of 20/20 may not quite see 20/100 at -2.25 He could perhaps be 20/120. There is also the issue of "just barely perceivable" This is what my diopter chart guidelines are for. For the lower amounts of myopia, the variance is going to be alot smaller. Also theres not going to really be "barely percievable" Because for small amounts of blur, its pretty straitforward but for large blurs, its more open to guessing and interpretation. I will explain each number with my opinion. This verson below has been rounded to .25 A. -0.75 .... 20/30 Everyone should be seeing that line with over 90% accuracy. If your having trouble then your also having trouble with 20/20 BCVA as well. Those who only see 20/40 arent going to fully be corrected to 20/20. Likewise those who have an easy time seeing this line and can see some or all of 20/25 are solid 20/20 and likley to see some 20/15 B. -1.00 .... 20/40 The great majority of people will see this line with over 90% accuracy. Those who fall closer to 20/50 are partial 20/20 at best. Likewise those who can see some or all of 20/30 are likley to be able to resolve part of 20/15 A. -1.25 .... 20/50 The majority of people will resolve this line with at least 90% accuracy. Some may fall closer to 20/60, only seeing half of this line, not enough to count. Likewise, its pretty common to be able to resolve half or even all of 20/40 with a solid 20/20 BCVA   B. -1.50 .... 20/60 Most people will pass this line with a diopter and a half of myopia. Depending how solid your 20/20 BCVA is, you may pass 20/50 with more than 2/3 accuracy or only see half of this line making you a 20/70 but with viturally 100% accuracy   A. -1.75 .... 20/70 This line may be blurry but if your a solid 20/20 you ought to not have trouble passing this line. There are still some who can pass 20/50 but they are partial 20/15 if not better. Likewise, some people fail this line. If you are having trouble seeing even 20/80 your BCVA probably wont stand a chance at passing 20/20 and you may not even be 100% accurate at 20/25   B. -2.00 .... 20/80 One optometrist said his patients with this pescription usually pass this line. A fair number of people can still pass 20/70 and they have solid 20/20 BCVA to say in the least. Some people may have trouble with this line despite still passing 20/20 and may be closer to 20/100 which is still fine but if your worse than that I doubt your correctable to 20/20   A. -2.25 .... 20/100 A solid 20/20 BCVA should pass this line. The deviation is typically from 20/70 to 20/150 depending on your BCVA. Some people despite passing 20/20 fall a bit shy of 20/100   B. -2.50 .... 20/120 Many people with this pescription have difficulty with 20/100. This is not a common line on snellen charts and usually the next step up is 20/150 if you fail 20/100. In fairness, youll score between the two with this amount of myopia. You should see 100% of 20/150 if your a solid 20/20 and some people can see part or enough to pass 20/100 especially with a solid 20/20 BCVA. If your better than 20/20 you may see better than 20/100 UCVA. I know one lady whos 20/15 and she can see this line no problem and barely pass 20/80   A. -3.00 .... 20/150 Although commonly stated 20/200, those with a solid 20/20 BCVA in fact should be seeing better than 20/200 and good enough to pass this line. Everyone correctable to 20/20 should pass 20/200 at minimum. Some people may not pass this line despite passing 20/20 but should pass 20/200 or I question their ability to see even partial 20/20 because I can pass 20/20 with a solid 20/30 BCVA   B. -3.50 .... 20/200 Although a seemly high dioptric amount, someone whos a solid 20/20 ought to pass 20/200. Theres no excuse not to see 100% of 20/200 with a BCVA better than 20/20. Those having trouble or unable to resolve 20/20 BCVA may be considered 20/300 UCVA or more perhaps 20/250 although ive never seen anything between 20/200 and 20/300 on snellen charts   A. -4.00 .... 20/250 Not a line seen on snellen charts, netherless its mentioned because many people with four diopters do fall between 20/200 and 20/300. It however is approperate to consider them 20/300 since this is the next line after 20/200. Most people will resolve 20/300 with BCVA in the 20/20 to 20/30 range. If unable to pass this line, your BCVA isnt very good. On the flipside, BCVA better than 20/20 is known to pass 20/200 in fact one young girl passed 20/200 with a -4 lense giving her 20/15 BCVA   B. -4.50 .... 20/300 Most people will consider you 20/400 with this dioptric amount. I can pass 20/400 with this diopters despite only seeing a solid 20/30 BCVA. One whos a solid 20/20 probably should pass 20/300 with this diopters. There is still debate if -4.5 should be 20/300 or if its "too much" for 20/300.   A. -5.25 .... 20/400 Most people will consider you worse than 20/400 with this diopters and its probably true many do fall just shy of this. Even being a solid 20/20, this line wont be easy to read. -5 diopters seems to be the generally accepted limit for 20/400 but I know two people who passes 20/400 at -5.5 Even if you can barely pass this line, being -5 and especially -4.75 certainly will make this line much easier and probably 100% pass too.   B. -6.00 .... 20/500 Not a common line on snellen charts, netherless its between 20/400 and 20/600. The majority of people would be considered 20/600 with this amount of myopia but in truth they may be able to resolve a little better than that. This is probably the limit for 20/400 and your gonna need to be at least 20/15 if not better to pass 20/400 with this much myopia which is already considered high myopia.   A. -6.75 .... 20/600 Probably need to be a solid 20/20 to pass this line. Being better than 20/20 or having a bit less than -6.75 diopters will certainly help achieve 100% accuracy of this line. Ive been told you need to be closer to -6 than -6.75 to pass 20/600. The range varies pretty widly at this point with some -5 diopter guys still being considered 20/600 while on the flipside, ive heard a few -7 diopter guys passing this line.   B. -7.25 .... 20/700 Never seen this line on a snellen chart. In truth, people with this much myopia can safely be considered 20/800. I dont think many will be able to pass 20/600 with this much myopia, although those with a solid 20/15 or better BCVA could be capable of passing 20/600. Most people should still pass 20/800, even I can when simulating this much myopia by wearing a plus lense.   A. -8.00 .... 20/800 Typically, the largest line on nearly all snellen charts. To be honest, I have not seen anything larger than 20/400 except on my own custom snellen charts I made myself. Even that, I would have to make by hand anything larger than 20/600 which needs two pages to fit, 20/800 wont even fit. 20/400 is the largest that will fit on a single page so I understand why the space constrictions limit most charts to 20/400. Also many people consider it a moot point if you cant see 20/400 then your vision is really bad, period. I dont have much experience in diopters vs. 20/xxx for the higher amounts of myopia because not very many people are this myopic and also few charts even go to 20/800 so I just hear high myopes say "im so blind, I cant even see the big 20/400 E" I do know one guy whos -7.5 barely seeing 20/800 who got lasik and ended up 20/20. Perhaps this is where my diopters to 20/xxx formula begins to break down. If very, very few people are seeing 20/800 at -8 but alot more people are seeing 20/400 at -5.25 then my formula of where 50% more myopia results in 50% visual accuracy ends here. Perhaps it becomes more expotentional beyond this point. My only experience was simulating with *two* plus lenses and my friend said due to the magnification, this isnt accurate. I did compenstate but she says its not the same as real myopia.nondisclosed_email@example.com (Myope5)Fri, 23 Dec 2005 14:55:53 +0000