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Medical Forum / General / Vision / December 2005Theoratical limit of human visual accuracy? How well is best possible with 100% perfect eyes
I did a search on google but couldnt find much. I did find that everyone agrees its 20/10, almost everyone agrees its 20/8, some agree its 20/5 and a few believe it can be even better! I know one guy who claims to be able to see the 20/10 line easy from 25 feet and even from a little more than 30 feet he can still see it, although he proclaimed it begins to lose shape around 30 feet. I told him hes definately better than 20/10 and probably 20/6 to 20/8. He also says he can discern 100fps and movies are a slideshow to him! He can see 240 degrees whereas normal people see 180-210 degrees! His night vision is almost as good as an owls too! We discussed his uber amazing vision and he says hes one of the best but goes on to add theres people that may see a little better than me, like 20/5 or even 20/4 and he knows one guy who claims hes 20/5! Theres a website where you can print a snellen chart that goes down to 20/4 so perhaps theres 5-10 guys/humans in the world who can see 20/4? I read that its commonly accepted hawks see 20/5 and its 20/2 for eagles! This in comparsion to 20/20 for a plano human! Some see better than 20/20, others worse. High order aberrations are largely to blame for this because I read that a healthy retina is capable of at least 20/8! Lots of people arent correctable to 20/20 due to high order aberrations(even compenstating for spectacle minification perhaps have them wear contacts) 20/20 is often referred to as perfect vision because this means nothing is wrong with your eyes and you also are plano. I wonder what 20/20 vision looks like, never mind 20/15, 20/10 or better! Is everything just very 3-D and really stands out? Are colors and contrast vivid? Do you see details no one else does like the leaf here: http://www.ibrium.se/desktop_picts/jpg/Ducouret/Leaf(915x629).jpg from a distance? or the bark of a tree like that from half a mile? http://www.prairiepoint.net/journal/images/P7260023.jpg I know one guy who > claims to be able to see the 20/10 line easy from 25 feet and even from > a little more than 30 feet he can still see it, although he proclaimed > it begins to lose shape around 30 feet. Begins to lose shape? This guy is delusional. I told him hes definately > better than 20/10 and probably 20/6 to 20/8. He also says he can > discern 100fps and movies are a slideshow to him! He can see 240 > degrees whereas normal people see 180-210 degrees! A nut case. Maybe with a huge exotropia, which would be the only possible explanation for the 240 degrees, and is plainly lying about the cff of 100. and its 20/2 for > eagles! Try searching on "diffraction limits" on visual acuity. Physics wins, B.S.ers lose. w.stacy, o.d. "Begins to lose shape? This guy is delusional." He begs to differ and would challenge anyone who doesnt believe him. Be warned its not for the faint of heart, he told me several people have actually fainted when he demostrated how good his vision was! One optometrist in his handwritting wrote tiny letters and he read it across the room then bam he was laying on the floor, had fainted! One optometrist literally threw him out of the room after he rapidly and effortlessly read the 20/10 line! Said he had godly vision or something and that it was a waste of his time. As for losing shape, anyone will note that if you stand far enough letters begin to look like ............ instead of l e t t e r s. "A nut case. Maybe with a huge exotropia, which would be the only possible explanation for the 240 degrees, and is plainly lying about the cff of 100." I think his 240 degrees is the threshold where your aware of some presence. You could walk diagonally behind me and I will be aware something crept behind me but I wont know what. I did have a pharphiel vision test and they said 200 degrees is when I was aware of the moving object but it had to be like 90 degrees before I could read the letter(s) on the card. As for seeing 100fps, ive seen several people claim this. They cant watch TV or movies without getting a headache as its a series of still frames! "Try searching on "diffraction limits" on visual acuity. Physics wins, B.S.ers lose." I did and already stated that theres some disagreement on this. One researcher claims humans could potentionally see 20/2.5 in theory which is what many eagles normally see but goes on to say 20/15 to 20/12 is the "typical" limit due to high order aberrations. He goes on to explain the limits of the retina and the spacing of the cones and the phenomeon of spatal antialising. In all, he believes 20/2.5 if your RMS(root mean square) of aberrations is absolutely zero and your pupils are huge. Huge pupils with aberrations results in more blur but in the absense of aberrations, it actually results in clearer vision! Any optometrists have any comments on this or anything reguarding the limits of vision? > letter(s) on the card. As for seeing 100fps, ive seen several people > claim this. They cant watch TV or movies without getting a headache as > its a series of still frames! In the US, TV is 30 fps, and yes there are some who can appreciate 30 fps, mostly with their peripheral vision. Still, it's a long way from there to 100 fps. > phenomeon of spatal antialising. In all, he believes 20/2.5 if your > RMS(root mean square) of aberrations is absolutely zero and your pupils > are huge. Huge pupils with aberrations results in more blur but in the > absense of aberrations, it actually results in clearer vision! Huge pupils make it much harder to reduce aberrations, if that matters. Whatever you think, the best real-life outcomes with wavefront PRK correction still come up around 20/10 on the Snellen chart, which is also about the best we can get with good gas perm contacts or glasses. "Better than normal," or "hyperacuity," is still unusual. > Any optometrists have any comments on this or anything reguarding the > limits of vision? Just that when you start talking about the finest resolutions, Snellen "equivalents" become less meaningful because Snellen results vary more than other measures, like vernier acuity. Which is probably the most sensitive measure we have for determining Minimum Angle of Resolution. -MT "In the US, TV is 30 fps, and yes there are some who can appreciate 30 fps, mostly with their peripheral vision. Still, it's a long way from there to 100 fps." TV has motion blur, movies and games dont so he sees still frames much easier. "Huge pupils make it much harder to reduce aberrations, if that matters." Yes because large pupils cover more aberrations and for most people, they see best with pinhole pupils, especially if they have a refractive error. However for those without aberrations they actually see better with dilated pupils, hence this guy with hyper vision sees almost as good as an owl at night! He can see his toes in pitch blackness! "Whatever you think, the best real-life outcomes with wavefront PRK correction still come up around 20/10 on the Snellen chart" He never got surgury and his vision is uncorrected! If you can get 20/10 with wavefront PRK you were seeing that good with corrective lenses in the first place. In fact many people corrected to 20/10 dont get 20/10 after laser surgury, sometimes not even with correction anymore. You need nearly perfect, nearly aberration free eyes to see 20/10 and laser surgury induces aberrations. I would not reccomend surgury to anyone correctable to 20/10, its too good a BCVA to risk. "which is also about the best we can get with good gas perm contacts or glasses." 20/10 is much more unusual with glasses because of minification and RGP doesnt minify plus provides the crispest vision. I have been told I "should" be getting 20/20 with RGP. Right now I get 20/30 with -5 glasses. -5 glasses make the 20/25 line too small to accurately see. ""Better than normal," or "hyperacuity," is still unusual." No kidding but I seem to see a fair amount of 20/15 vision with or without correction. I guess 20/10 is where hyperacurity starts. Snellen accuracy is something we are all familiar with. I didnt even know vernier accuracy till I looked it up. Also I could score well on the vernier but not well on the snellen. Optometrists use the snellen as a benchmark of vision accuracy and its the most popular test "I was going to reply to this, but I realized that this isn't sci.med.humor." sir, I am not joking here. I asked a serious question. "Ok, Ok. So maybe he's a troll, or just having fun." Not a nice thing to say or assume about me, sir. I know your a good optometrist and I respect you so we must have a misunderstanding there. I am interested in this discussion and knowing about the limits of human vision. > Not a nice thing to say or assume about me, sir. I know your a good > optometrist and I respect you so we must have a misunderstanding there. > I am interested in this discussion and knowing about the limits of > human vision. Sorry, but you seem very, very gullible at the least. You need to learn to be a little more skeptical, especially of spectacular single case claims by anyone, which are known in the science field as testamonials and in the statistics field as n=1 self studies. In law your post is called hearsay and is not allowed in court for a multitude of good reasons. This group is called SCI.med.vision because we try to keep it scientific. If you want to be a scientist, get this guy to submit to a real evaluation of his self-claimed super vision by a neutral scientist using proper technique. It would still be n=1 but might qualify as a case report rather than a simple hearsay testamonial. w.stacy, o.d. > This group is called SCI.med.vision because we try to > keep it scientific. If you want to be a scientist, get this guy > to submit to a real evaluation of his self-claimed super > vision by a neutral scientist using proper technique. He covered that, remember? The first guy swooned and the second threw him out. -Quick > TV has motion blur, movies and games dont so he sees still frames much > easier. What if they show a movie on TV? :) Seriously I think your friend is overstating his abilities. > Yes because large pupils cover more aberrations and for most people, > they see best with pinhole pupils, especially if they have a refractive > error. However for those without aberrations they actually see better > with dilated pupils, hence this guy with hyper vision sees almost as > good as an owl at night! He can see his toes in pitch blackness! I don't see the connection between minimum angle of resolution and scotopic sensitivity. > anymore. You need nearly perfect, nearly aberration free eyes to see > 20/10 and laser surgury induces aberrations. Oh. I thought the purpose of wavefront surgery was to reduce aberrations. > glasses. -5 glasses make the 20/25 line too small to accurately see. Most of the -500 myopes I see can get 20/20 or better with their glasses. Minification may not explain your problem. > Snellen accuracy is something we are all familiar with. I didnt even > know vernier accuracy till I looked it up. Also I could score well on > the vernier but not well on the snellen. Optometrists use the snellen > as a benchmark of vision accuracy and its the most popular test So do medical doctors and a host of others. But recognizing letters involves much more than just acuity or aberration. From here on, you quoted someone else. > "I was going to reply to this, but I realized that this isn't > sci.med.humor." [quoted text clipped - 7 lines] > I am interested in this discussion and knowing about the limits of > human vision. "What if they show a movie on TV? :) " Hes referring movies as the ones you see in theaters. Its a series of still frames to him so he almost never goes to theaters. TVs are more tolerable due to motion blur but still annoys him but he deals with it. "Oh. I thought the purpose of wavefront surgery was to reduce aberrations." technicially it does vs. standard lasik. wavefront induces less aberrations. In highly aberrated eyes, wavefront offers some relief but in virgin eyes youll get induced aberrations. I dont think ive seen a single person really end up 20/10 after lasik. Inflated results dont count. Is guessing allowed? The standard is to get the majority of letters right, more than 2/3 of said line. I read that doctors/surgeons like to inflate results to make their stats look good. I speak from experience when I went to one of those for an eye exam, I read/guessed maybe half of the 20/25 line and could see none of the 20/20 but he said guess so I did and got one right then he wrote down im 20/20 to 20/25 with a -5 lense on the phororaptor. "Most of the -500 myopes I see can get 20/20 or better with their glasses. Minification may not explain your problem." see above. That technician considered me a partial 20/20. True 20/20 is alot less common, especially with the minification of a -5 lense. No one in my family is really correctable to 20/20. My mom can see 20/30 and some of the 20/25 with contacts and only 20/30 with her -7.5 glasses. My fathers a +6 and yet hes only correctable to 20/25 but he may be able to see/guess some of the 20/20. My brother had an eye exam and despite he being a -1(not much minification) he could not see all of the 20/20. I think he got 3 out of 5. My sister has about 80-90% accuracy of 20/20 with contacts which is good enough to count, Ill give her credit for 20/20. My sister's friend has the best vision ive seen. She told me her optometrist recorded her as 20/10 but she isnt. I watched her read a standard snellen chart and she did get all of the 20/15 line and 80% of the 20/13 line and like 2 of the 20/10 line. Hey if you blindfold me and let me guess the 20/10 line I could get lucky and get a few right. Means nothing. I could also guess where the dice will land. I do give her credit for 20/13. At one store I told her to stand back as far till she can just barely make out the sign. I then stood back myself. I was amazed to see that she was standing back twice as far, maybe a bit more than I was! This would make me worse than 20/25, perhaps 20/28 with -5 and I could probably get about 80% of the 20/25 line with proper contacts since they dont minify so the 20/25 line will be a little bigger. So im only one line away from perfect 20/20 BCVA without minification, minification is an artifical limit, many high myopes see 20/25 with glasses but the 20/25 they see is about the same size as the 20/20 line with contacts. Having a few extra high order aberrations or a little irregular astigmastim can easily mean one line difference. How do you explain some being 20/15 BCVA while others 20/25? Obviously someone whos only a -1 is much more likley to see 20/20 than someone whos a -5 and especially higher. With contacts its all equal(20/20) as long as the retina is fine and you dont have a whole lot of aberrations. I think optometrists are being quite generous reguarding BCVA. I remember one time I looked into a vision screener with my full power glasses and I read 20/40 and half of the 20/30 in the left and my worse right eye was struggling to see 20/40. I can definately tell the right eye isnt as good as the left when looking about the store and closing one eye at a time. I consider myself 20/30 with -5 glasses to put it simply. "You need to learn to be a little more skeptical, especially of spectacular single case claims by anyone" I am indeed skeptical but he insists hes telling the truth. I did a search online and read that the retina is indeed possible of better than 20/10 so while hes a very rare case of hypervision, its potentioanlly true. Hes just got very special, aberration free eyes! "law your post is called hearsay" whatever happened to freedom of speech? This is not a trial so no one is under oath of perjury. Besides if this is misinformation, its his fault, not mine! "If you want to be a scientist, get this guy to submit to a real evaluation of his self-claimed super vision by a neutral scientist using proper technique." I told him, he doesnt seem to care. Is there anything good in it for him? If there is, I will point it out and get him to submit to eye exams by optometrists and scientists. William, what was the best visual accuracy youve personally seen? How rare is 20/10 even? > "law your post is called hearsay" > > whatever happened to freedom of speech? This is not a trial so no one > is under oath of perjury. Besides if this is misinformation, its his > fault, not mine! In a court setting, it's not allowed because of the certainty that the facts will be distorted on the 2nd hand retelling. Free speech does not apply when the judge says "sustained" to the objection of hearsay. The witness must shut up. If it's misinformation IT IS YOUR FAULT for spreading the garbage here as if it were fact. Nobody's under oath, but I'm telling you to shut up with the hearsay and testamonials. It's my freedom of speech. > "If you want to be a scientist, get this guy to submit to a > real evaluation of his self-claimed super vision by a neutral scientist [quoted text clipped - 5 lines] > exams by optometrists and scientists. William, what was the best visual > accuracy youve personally seen? How rare is 20/10 even? Of course he doesn't. Nobody who exaggerates his physical prowess wants to submit to independent examination. The fact is, the ones who exaggerate are often the ones with less than average prowess. I see 20/10 regularly. I don't routinely test below 20/10 because my exam rooms are not set up for it. There's a good reason standard eye exam rooms are not set up to test for better than 20/10. Can you guess what that is? w.stacy, o.d. "Of course he doesn't. Nobody who exaggerates his physical prowess wants to submit to independent examination. The fact is, the ones who exaggerate are often the ones with less than average prowess." Good point. However hes probably still 20/10 but exaggerates how well he sees and all that. is 20/10 something to brag? I would imagine it sure is good enough to! "I see 20/10 regularly." What is the prevelence of 20/10 uncorrected? 20/10 best corrected? Are they really 20/10 or are they guessing/memorizing the 20/10 line? Hey if you want me to guess I might pass for 20/20 by getting 1 or 2 correct. ". I don't routinely test below 20/10 because my exam rooms are not set up for it." Woudlnt it be funny if any(even one) of them are a little or alot better than 20/10? Almost all eyecharts only go down to 20/20, 20/15 and sometimes 20/10. Theres an eyechart online you can print that goes below 20/10 at 20/8, 20/6, 20/5 and 20/4! "There's a good reason standard eye exam rooms are not set up to test for better than 20/10. Can you guess what that is?" guessing, memorizing, difficult to print such small letters, waste of space on eyechart, way too rare for better than 20/10, protecting the optometrist's sanity(yes some have fainted!) "Your friend's claim remains pretty incredible, but aside from that..." hey hes welcome to visit you or any creditable optometrist for proof. "I'm curious about your concept of a "virgin" eye, one having "no aberrations". Yes, LASIK can induce aberrations but it isn't usually discussed without knowing which type of aberration you mean. Some are more annoying than others, and reducing one often raises another. I gather you think that's common?" Virgin eyes have less aberrations than post lasik eyes. We can discuss this fully over at the google groups lasik forums. "That's a whole field in itself called "psychophysics." Most tests aren't accurate until you guess. And "majority" means "more than half."" Hey I could go to a store and see a price tag from a distance and "guess" what numbers are showing. Chances are I may end up correct. I wont know if im right or wrong till I move closer. You could call me 20/25, 20/20, whatever you want to call me but I wont be seeing letters as far as someone whos a true 20/20. Someone who sees half of the 20/20 could be considered 20/25+ but wont see quite as well as a full 20/20 "Refraction problems can result from poor communications, poor instructions, and poor technique on the part of the examiner. But you've had more than one doctor who couldn't get you to 20/20, right?" occasioanlly, someone will get a bad refraction. I have never been 20/20 in my life. My eyes are good but not perfect enough to see 20/20 and the minification of -5 lenses doesnt help any and in fact makes 20/25 too small to reliabily see. "I've examined a few like that. In some cases, corneal aberrations were involved and they saw better with contacts than with glasses. In other cases, refraction could be proven perfect and still there were limits on how well the vision could be corrected." Just a few? No one in my family is true 20/20! Ive had friends who bragged they were 20/20 but I could see signs as far away as they could! One lady says shes 20/20(uncorrected!) and I had her read a sign at an airport, moving closer till she could read it out correctly. I had to move closer till I was 3/4 the distance. Do the math, this doesnt make her quite 20/20. She could have 1/4 diopters myopia or astigmastim, thats all it takes or the vision she saw was the best vision she was going to have irreguardless. I know alot of friends who actually have a very slight refractive error but its too slight to need any action. Many may have 1/4 or 1/2 diopter astigmastim, myopia or hyperopia. Some have more high order aberrations than others and consequencly cant really see 20/20 while other eyes are much more perfect and they see better than 20/20. True 20/20 is quite hard! Read the excerpts I got off websites below. You've heard the term 20/20 to describe healthy vision. But do you know what it means? It's a standard devised to measure someone's eyesight relative to the average. If you have 20/20 vision, it means that from 20 feet away, you can see what the average person sees from 20 feet. Few people have this supposedly "normal" vision, considering that 61% of Americans wear some form of corrective lenses. People with poor eyesight have a higher second number. A person with 20/40 vision can only see from 20 feet what a person with normal vision can see from 40 feet. 20/200 vision is considered legally blind in the U.S. JULIUS SHULMAN, MD: Well, it's possible now to see better than 20/20 with contact lenses, with glasses or with PRK and Lasik. These procedures or contacts or glasses will let you see as well as your eye will allow. Not everyone has the potential for 20/20. Some people have 20/25, some 20/15. It's what your eye will allow. I also read an article that says 1 in 4 people can fully see 20/20! See the above, Julius even goes out to say that not all eyes have potentional for 20/20, you see as well as the eye allows! Seeing less than 20/20 does not neccessairly mean theres a disease, its just the optics of the eye(cornea, lense, retina, etc) "The everyday test for this is a pinhole. If you can see 20/25 through a pinhole held close to your eye, it's likely your problem is optical. If you can't see 20/30 through a pinhole, there may be some reason other than optics." I agree with you! I think some people are too quick to jump to the fact if anyone isnt 20/20 they must have something wrong! I most certainly see all of 20/25 in the left and half of 20/25 in the right with a small pinhole in front of my glasses. Therefore I have an optical issue limiting me, namely high order aberrations. "But I can tell you that it's "normal" for young, healthy -5 myopes to see 20/15, minification or not. You have no minification when you wear contacts." only if the eye allows this as Julius points out in the article. The eye would need to allow for a little better than 20/15 to see 20/15 with -5 glasses but for contacts its not an issue. Anyone thats correctable this good is lucky and fortunate to have very good optics and few aberrations. "After reading the 20/10 line, he--literally--read the patent number on the bottom of the chart." Thats another person with hypervision. What do you say he has? 20/6 vision? "A question is fine. You posted about somebody having 20/4 vision." no, I said 20/6 I said I have an eyechart that goes down to 20/4, you can print eyecharts that go to anything you want(within the limits of the printer of course) 1 > Good point. However hes probably still 20/10 but exaggerates how well > he sees and all that. is 20/10 something to brag? I would imagine it > sure is good enough to! 20/10 is very good. Brag? I suppose so, although bragging in general seems to be a sign of insecurity. > What is the prevelence of 20/10 uncorrected? among young adults, probably 10% 20/10 best corrected? among young adults, probably 30% Are > they really 20/10 or are they guessing/memorizing the 20/10 line? Hey > if you want me to guess I might pass for 20/20 by getting 1 or 2 > correct. Guessing is allowed, memorizing is not (any good VA measurer should have a variety of letters to present, including tumbling Es, Landolt Rings, and numerics. Random generators are the best, of course. 1 or 2 correct does not get you 20/20. You have to get most of the letters, and if you miss some, the 20/20 designation is appended with something like 20/20 -2 (meaning missed 2 letters on the 20/20 line, usually out of 6 presentations) If you got all the 20/25 letters, and picked out 2 on the 20/20 line, I would notate that as 20/25 +2 Theres an eyechart online you can print that goes > below 20/10 at 20/8, 20/6, 20/5 and 20/4! Why bother? Just take a 20/10 line and back the subject up to 40 ft. away from it. Instant 20/5. Not exactly rocket science. > "There's a good reason standard eye > exam rooms are not set up to test for better than 20/10. Can you guess [quoted text clipped - 3 lines] > space on eyechart, way too rare for better than 20/10, protecting the > optometrist's sanity(yes some have fainted!) Wrong answers. It's that 20/10 is close to the threshold of theoretically possible human acuity. No rocket science there, either. w.stacy, o.d. I looked on google and this is what I found. "20/10 is not undesirable; it is both highly desirable, and extremely rare." "Seven out of ten letters on any line is satisfactory." "A small percentage of the population is blessed with vision better than 20/20" "Only about 35 percent of all adults have 20/20 vision without glasses, contact lenses or corrective surgery. With corrective measures, approximately 75 percent of adults have this degree of visual acuity while the other 25 percent of the population just doesn't see very well, Dr. Johnson says." I also found websites that give different figures for 20/10 vision but all say its extremely rare and one said 1 in 1000 see 20/10. How can 10% of adults be 20/10 if only 35% are even 20/20? You further add that 30% are 20/10 with glasses, which by the way minify so theyd have to be BETTER than 20/10 to see 20/10 with glasses. How can 30% be 20/10 BCVA when only 75% are even corrected to 20/20 or better? You appearently dont see alot who cant see 20/20 but 25% cant which is a fair amount. I dont know how you conduct your testing but I have to respectfully disagree with you. Hey one opometrist considered me 20/20 with glasses even though I could see none of the 20/20 line! As for guessing, theres always the luck factor and if the person is borderline between two lines, he could get lucky and guess his way. There is the phenomeon of shape/blur reconization. The 20/10 line could look something like this: ..-.,,.., The larger dots could be guessed between a choice of big letters like E, H, F, the small roundish dots like an O, C, D. The long skinny dots like an L, P, F. If you used numbers and didnt tell the person, he would get everyone of them wrong, assuming they are letters and guess on a best fit depending on the shape of the dot. There is a big difference between actually being able to see the letters and guessing on shape/blur reconization and getting some right with luck. Using tumbling E's avoids this and gives a 25% chance. Test him with at least 10 different tumbling E's and also ask him to be honest, is he actually seeing the E's or just guessing? Hey youd probably also consider me 20/20 if I had an eye exam at your office but I definately dont see as well as a true 20/20. I had a 20/20 friend move closer and closer till she could read the sign in the airport and I had to be quite a bit closer to see it. > I looked on google and this is what I found. > > "20/10 is > not undesirable; it is both highly desirable, and extremely rare." Please give a URL for that quote. > "Seven out of ten > letters on any line is satisfactory." And that one. Satisfactory for what? > "A small percentage of the population is blessed with vision better > than 20/20" Nutty. I'd love a URL for that one. > "Only about 35 percent of all adults have 20/20 vision without glasses, > contact lenses or corrective surgery. With corrective measures, > approximately 75 percent of adults have this degree of visual acuity > while the other 25 percent of the population just doesn't see very > well, Dr. Johnson says." Dr. Johnson? who is he? His numbers are whacked. You further add that > 30% are 20/10 with glasses, which by the way minify so theyd have to be > BETTER than 20/10 to see 20/10 with glasses. What? Only MINUS Rx's minify. More than half the Rx's I write are +, that's PLUS, or MAGNIFYING Rxs. These HELP people see smaller print. What is wrong with you? Are you Otis' only child or what? Why do you ignore the fact that MOST PEOPLE WEARING GLASSES ARE WEARING PLUS LENSES, NOT MINUS LENSES!!!!! How can 30% be 20/10 BCVA > when only 75% are even corrected to 20/20 or better? What? Is it unreasonable that if 75% can see 20/20 or better that a third of those will see 20/10? Crazy, at least. w.stacy, o.d. you can find it all on google and then some. Here is one link reguarding its rare to be blessed better than 20/20 http://ask.yahoo.com/20000726.html "Dr. Johnson? who is he? His numbers are whacked." Its common for doctors to disagree with each other. Sad to say, I have to side with him. Considering so many people have all kinds of vision problems, its not supprising in the least not to be 20/20 and at least 25% cant correct to 20/20 either. Ive told you my entire family cant correct to a full 20/20 and alot of my friends cant either. "More than half the Rx's I write are +, that's PLUS, or MAGNIFYING Rxs. These HELP people see smaller print." considering myopia is much more common and prevelent than hyperopia. Also young hyperopes arent bothered much unless its severe or they do alot of near work then they simply can use reading glasses. post-presbyopic hyperopes see blurry at all distances so they definately do need glasses and bifocals at that. You are right about the magnification. Hey I think your testing their NEAR vision and they are reading 20/10. This is perfectly normal and especially common for hyperopes. I apologize for the confusion. "What? Is it unreasonable that if 75% can see 20/20 or better that a third of those will see 20/10?" If were talking hyperopes with magnification plus glasses looking at a near snellen chart then this is perfectly reasonable. Distance charts are an entirely different beast. > Its common for doctors to disagree with each other. Sad > to say, I have to side with him. Considering so many [quoted text clipped - 3 lines] > family cant correct to a full 20/20 and alot of my > friends cant either. and you told us one of your friends sees at 20/4... So? I'm really confused as to your point or adgenda. Do you have a question? Is it the one in the subject? If you are asking the question why are you arguing for your own answer? If you already have the answer what is your adgenda? To amaze and impress? Are you looking for recognition or support? What is it you are trying to accomplish here? I thought the first one or two exchanges were of interest but it's getting pendantic. Maybe I just missed the point? -Quick I never said 20/4 except that you can print an eyechart that goes down to 20/4. He was claiming 20/6 vision. I have googled hypervision and got some interesting articles. One article believes humans can theoratically see up to 20/2.5! Thats nearly the 20/2 eagles see and twice the 20/5 hawks see! Of course the wonderful thing called high order aberrations is what limits "normal" human vision to 20/20 with many actually seeing less than that and a few seeing better. I read about bionic eyes where they can bypass the retina limit and dont even get me started on the brain's limit but they say the brain is flexable and can "learn" to see again compared to your old and now "terriable" 20/20. Damn imagine bionically altered eyes(replace your retina with one with much more and denser cones?) and seeing like an eagle! > I never said 20/4 except that you can print an eyechart that goes down > to 20/4. He was claiming 20/6 vision. I have googled hypervision and > got some interesting articles. One article believes humans can > theoratically see up to 20/2.5! Thats nearly the 20/2 eagles see and > twice the 20/5 hawks see! I have really good vision. I can see things that you can only see with a microscope, and things you can only see with a telescope. In fact, that's how I do it!  SignatureDan Abel dabel@sonic.net Petaluma, California, USA > I can see things that you can only see with >a microscope, and things you can only see with a telescope. In fact, >that's how I do it! > > Can you imagine the powers of the minus lenses that are incorporated in those instruments? How evil and hard they must be on your eyes, no doubt stair-stepping you to heaven... w.stacy, o.d. > Can you imagine the powers of the minus lenses that are incorporated in > those instruments? How evil and hard they must be on your eyes, no doubt > stair-stepping you to heaven... Most of the evil mojo is absorbed by the plus lenses incorporated in chromatic pairs. -MT >you can find it all on google and then some. Here is one link >reguarding its rare to be blessed better than 20/20 > >http://ask.yahoo.com/20000726.html > > That link does not say that, at least not today. Try again. Please back up your outrageously incorrect statements. >"Dr. Johnson? who is he? His numbers are whacked." > [quoted text clipped - 5 lines] > > I repeat. Who is he? What kind of doctor? Perhaps he practices in a low vision clinic and never sees normal eyes. Perhaps he is some crazy myopic Ph.D. in biochemistry who thinks everyone is like himself. >"More than half the Rx's I write are +, >that's PLUS, or MAGNIFYING Rxs. These HELP people see smaller print." > > you said: considering myopia is much more common and prevelent than hyperopia. Obviously you've never seen the distribution of refractive errors, which in all populations says exactly the opposite to your statement. >"What? Is it unreasonable that if 75% can see 20/20 or better that a >third of those will see 20/10?" > >If were talking hyperopes with magnification plus glasses looking at a >near snellen chart then this is perfectly reasonable. > No, because no near acuity chart I've ever seen goes down to the equivalent of 20/10. Now you actually would be talking near the capabilities of modern laser printers. I was always referring to 20/10 distance acuity. My last post needs no corrections, thank you very much. w.stacy, o.d. >> you can find it all on google and then some. Here is one link >> reguarding its rare to be blessed better than 20/20 [quoted text clipped - 5 lines] > That link does not say that, at least not today. Try again. Please > back up your outrageously incorrect statements. OK so maybe it does say that down at the bottom, as part of a sentence that is obviously not from any expert in the field and is completely wrong. I had clicked on one of the hyperlinks and got side tracked. Only goes to show you that you can get anything on the internet, including wrong information from a layperson.. Always consider the source. w.stacy, o.d. "Obviously you've never seen the distribution of refractive errors, which in all populations says exactly the opposite to your statement." every website says myopia is much more prevelent and getting worse too! In Japan some 80% are myopes with 20% hyperopes or emmetropes. "I was always referring to 20/10 distance acuity." you said 20/10 is near the human limit of vision, how is that 30% see that with glasses, even plus glasses? They arent going to magnify the 20/10 line 100% so its the size of 20/20! High hyperopes may indeed see some or all of the 20/15 line but only because its equal or near the size of the 20/20 line emmetropes see. Hey I could see 20/10 from a great distance away with strong binoculars! "Can you imagine the powers of the minus lenses that are incorporated in those instruments? How evil and hard they must be on your eyes, no doubt stair-stepping you to heaven..." LOL :) "Thanks. The limitation of human vision is related to the distance between the millions of cones in the macula. A 20/10 eye is blessed with anatomy like high speed film, with smaller and closer receptors." Theres NO way 10% of people see 20/10 uncorrected or 30% with glasses, period. Its not just having more cones, youd need to be relativetly free of high order aberrations as well. Heck at least 25% of people dont even get 20/20 with glasses and I bet many who "see" 20/20 are really struggling to do so, guessing and missing. A true 20/20 can read all of that line clearly and rapidly without guessing ""Normal" 20/20 eyes are like low speed film, with a greater distance between receptors. Perfect wavefront spectacles won't give 20/6 vision to just anyone, only those blessed with the right anatomy." High order aberrations may also be responsable for this. I read that a normal healthy retina should be achieving better than 20/10 so someone seeing 20/20 probably hasnt hit the retinal limit yet, just has a few high order aberrations holding him back. Hey ive been told I could and should resolve 20/20 with RGP contacts yet im only 20/30 with glasses. RGP wont do anything for the retinal cone density burt it provides a smooth surface on your cornea, thereby masking some aberrations. Hey if you removed ALL my aberrations I very well may be resolving 20/8 if not better. "And if you ever can get such a pair of glasses, they have to glue them in an excact position on your face. Futhermore, you have to keep looking straight ahead. Meaning there are no ''wavefront'' glasses as there are no ''wavefront'' contactlenses either." There ARE wavefront glasses but they only work if you look strait ahead and percisely line up the aberrations. I was thinking of getting those so I can get 20/20 or better but my friend knows a bunch of friends who got them, many to try and fix their post lasik eyes. She said none of them saw a real difference with wavefront glasses. She also says if you want great vision, forget wavefront glasses, get custom z-wave fitting RGP contacts, they will do you a world of good! bump for the others to read and reply! You wan't more people to see what a total w.nker you are? Well, I will help them too. Ace, you are a total w.nker who knows nothing about what you are talking about. You are so stupid that you have no tiny understanding that refractive error is totally unrelated to VA. Magnification via spectacle lenses is irrelevant. You can try to justify your pathetic existance, but it still remains just that - pathetic. For god's sake, crawl back into your hole. dr grant Perhaps I can be of assisance? Refractive errors always result in decreased uncorrected visual accuracy. Hence the complaint of blurry vision. Greater errors can result in worse than 6/60 UCVA. Glasses minify or magnify and it is revelent. Have you ever looked into binoculars? Glasses act like this, but on a lesser scale. Minus glasses are like looking at the wrong end of binoculars while plus glasses act like weak binoculars. Dude, I can not see 20/20, especially with my -5 glasses, just way too small. > and sometimes 20/10. Theres an eyechart online you can print that goes > below 20/10 at 20/8, 20/6, 20/5 and 20/4! > "After reading the 20/10 line, he--literally--read the patent number on > [quoted text clipped - 8 lines] > can print eyecharts that go to anything you want(within the limits of > the printer of course) There's this little thing called "physics". Sometimes they even call them the "laws of physics". The limits of the printer don't define the "laws of physics". You are posting nonesense. Once again. SignatureDan Abel dabel@sonic.net Petaluma, California, USA > Hes referring movies as the ones you see in theaters. Its a series of > still frames to him so he almost never goes to theaters. TVs are more > tolerable due to motion blur but still annoys him but he deals with it. Your friend's claim remains pretty incredible, but aside from that... Motion blur occurs at the camera. Since we're talking about movies, the blur would be recorded on film and would reproduce the same whether projected onto a white screen or a phosphor tube. There's a difference between those two projection methods, but it isn't "motion blur." You might mean "persistence." > "Oh. I thought the purpose of wavefront surgery was to reduce > aberrations." > > technicially it does vs. standard lasik. wavefront induces less > aberrations. In highly aberrated eyes, wavefront offers some relief but > in virgin eyes youll get induced aberrations. I'm curious about your concept of a "virgin" eye, one having "no aberrations". Yes, LASIK can induce aberrations but it isn't usually discussed without knowing which type of aberration you mean. Some are more annoying than others, and reducing one often raises another. I gather you think that's common? There's good information about aberrations at http://www.emedicine.com/oph/topic744.htm. > dont think ive seen a > single person really end up 20/10 after lasik. How many have you examined? > Is guessing allowed? The standard is to get the majority of > letters right, more than 2/3 of said line. That's a whole field in itself called "psychophysics." Most tests aren't accurate until you guess. And "majority" means "more than half." > I read that doctors/surgeons > like to inflate results to make their stats look good. There may be more about that in the LASIK newsgroup. > I speak from > experience when I went to one of those for an eye exam, I read/guessed > maybe half of the 20/25 line and could see none of the 20/20 but he > said guess so I did and got one right then he wrote down im 20/20 to > 20/25 with a -5 lense on the phororaptor. Refraction problems can result from poor communications, poor instructions, and poor technique on the part of the examiner. But you've had more than one doctor who couldn't get you to 20/20, right? I've examined a few like that. In some cases, corneal aberrations were involved and they saw better with contacts than with glasses. In other cases, refraction could be proven perfect and still there were limits on how well the vision could be corrected. The everyday test for this is a pinhole. If you can see 20/25 through a pinhole held close to your eye, it's likely your problem is optical. If you can't see 20/30 through a pinhole, there may be some reason other than optics. Technically, the non-optical limitation is defined as amblyopia, a neurological problem. Sometimes it's developmental, like wires that never completely connected. Sometimes it's due to toxicity or demyelination, malnutrition, or birth defect. Many times you can't find out why until autopsy. > see above. That technician considered me a partial 20/20. True 20/20 is > alot less common, especially with the minification of a -5 lense. That simply isn't true. And you misspelled "lens." Then you went on to mention that your entire family has the same problem, on both sides. Are you from Louisiana? (Duck-n-roll) > I think optometrists are being quite generous reguarding BCVA. I > remember one time I looked into a vision screener with my full power [quoted text clipped - 3 lines] > one eye at a time. I consider myself 20/30 with -5 glasses to put it > simply. It's hard to tell more about your situation without examining you. But I can tell you that it's "normal" for young, healthy -5 myopes to see 20/15, minification or not. You have no minification when you wear contacts. And you're mixing quotes again.----- -MT > "You need to learn > to be a little more skeptical, especially of spectacular single case [quoted text clipped - 20 lines] > exams by optometrists and scientists. William, what was the best visual > accuracy youve personally seen? How rare is 20/10 even? William Stacy wrote: (what looks like an empty post, sorry; here's what I intended to post in response to aceman): > "law your post is called hearsay" > > whatever happened to freedom of speech? This is not a trial so no one > is under oath of perjury. Besides if this is misinformation, its his > fault, not mine! In a court setting, it's not allowed because of the certainty that the facts will be distorted on the 2nd hand retelling. Free speech does not apply when the judge says "sustained" to the objection of hearsay. The witness must shut up. If it's misinformation IT IS YOUR FAULT for spreading the garbage here as if it were fact. Nobody's under oath, but I'm telling you to shut up with the hearsay and testamonials. It's my freedom of speech. > "If you want to be a scientist, get this guy to submit to a > real evaluation of his self-claimed super vision by a neutral scientist [quoted text clipped - 5 lines] > exams by optometrists and scientists. William, what was the best visual > accuracy youve personally seen? How rare is 20/10 even? Of course he doesn't. Nobody who exaggerates his physical prowess wants to submit to independent examination. The fact is, the ones who exaggerate are often the ones with less than average prowess. I see 20/10 regularly. I don't routinely test below 20/10 because my exam rooms are not set up for it. There's a good reason standard eye exam rooms are not set up to test for better than 20/10. Can you guess what that is? w.stacy, o.d. > "I was going to reply to this, but I realized that this isn't > sci.med.humor." > > sir, I am not joking here. I asked a serious question. A question is fine. You posted about somebody having 20/4 vision. SignatureDan Abel dabel@sonic.net Petaluma, California, USA > Theres a website where you can print a snellen chart that goes down to > 20/4 so perhaps theres 5-10 guys/humans in the world who can see 20/4? I was going to reply to this, but I realized that this isn't sci.med.humor. SignatureDan Abel dabel@sonic.net Petaluma, California, USA Ok, Ok. So maybe he's a troll, or just having fun. Plonk. >>Theres a website where you can print a snellen chart that goes down to >>20/4 so perhaps theres 5-10 guys/humans in the world who can see 20/4? > > I was going to reply to this, but I realized that this isn't > sci.med.humor. My eldest brother drove me to an ophthalmologist appointment once. While I was reading the eye chart, Allen stood over my left shoulder--maybe two or three feet further from the wall than I. After reading the 20/10 line, he--literally--read the patent number on the bottom of the chart. I love my brother, but--needless to say--I don't /like/ him very much, and I don't get rides to the eye doc from him anymore.... SignatureLive simply so that others may simply live This post made me laugh, my first chuckle of the day. Thanks. The limitation of human vision is related to the distance between the millions of cones in the macula. A 20/10 eye is blessed with anatomy like high speed film, with smaller and closer receptors. "Normal" 20/20 eyes are like low speed film, with a greater distance between receptors. Perfect wavefront spectacles won't give 20/6 vision to just anyone, only those blessed with the right anatomy. > The limitation of human vision is related to the distance between the > millions of cones in the macula. More precisely it is the foveolar region of the macula where you ''get'' your highest separation. > A 20/10 eye is blessed with anatomy > like high speed film, with smaller and closer receptors. "Normal" > 20/20 eyes are like low speed film, with a greater distance between > receptors. As long as those receptors are connected in a one-to-one way with the midget bipolar- and the midget ganglion cells you are right. Meaning, it is not only the size that matters, also the way they are connected does (among other things). Perfect wavefront spectacles won't give 20/6 vision to just > anyone, only those blessed with the right anatomy. And if you ever can get such a pair of glasses, they have to glue them in an excact position on your face. Futhermore, you have to keep looking straight ahead. Meaning there are no ''wavefront'' glasses as there are no ''wavefront'' contactlenses either. SignatureJan (normally Dutch spoken) |
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