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Medical Forum / General / Vision / March 2005Reliability of the autorefractometer
It seems my prescription changes with the autorefractometer used. I have gone for several eye tests and my prescription has varied from the very best at -2.25(Left Eye) and -2.75(Right Eye) to -2.50(Left Eye) and -3.25(Right Eye). My question is what sort of lighting should the eye test be done in? Because obviously the lighting would affect the results. Dear Andrew, Subject: Test conditions Illumination has a provound effect on visual acuity. One man passes all legal requirements for vison, i.e., he reads 1.8 cm letters at 6 meters -- in room illumination. When placed in semi-darkness, it takes a -2.0 diopter to clear the 20/20 line. Hope this clarifies your question. Best, Otis Engineer > Dear Andrew, > Subject: Test conditions [quoted text clipped - 12 lines] > Otis > Engineer You know I wouldn't be surprised if people with normal vision would fail the eye test in the optometrist's dark room... > You know I wouldn't be surprised if people with normal vision would fail > the eye test in the optometrist's dark room... Then you never have entered a optometrist's room. When measuring for prescribing the room is not dark. You are not mistaken by any chance one type of "darkroom'' with another ? grins.........  SignatureJan (normally Dutch spoken) >> You know I wouldn't be surprised if people with normal vision would fail >> the eye test in the optometrist's dark room... > > Then you never have entered a optometrist's room. > When measuring for prescribing the room is not dark. Well all the ones I've gone to are not bright either. They are either rather dark or dim. Perhaps, as you say, I've not been in a real optometrist's room. >>> You know I wouldn't be surprised if people with normal vision would >>> fail the eye test in the optometrist's dark room... [quoted text clipped - 5 lines] > rather dark or dim. Perhaps, as you say, I've not been in a real > optometrist's room. The room might be dim, but the eye chart is not, and it has plenty of contrast. Scott > You know I wouldn't be surprised if people with normal vision would fail > the eye test in the optometrist's dark room... Do you know what depth-of-field is? -MT >> You know I wouldn't be surprised if people with normal vision would fail >> the eye test in the optometrist's dark room... > > Do you know what depth-of-field is? As you said yourself, doctors cannot even agree what ambient lightning should be used for testing, itself a subjective evaluation. We all know depth of field decreases in dim light because the pupil dilates, so someone who might pass the test in bright light would fail if it's done in poor lighting. > As you said yourself, doctors cannot even agree what ambient lightning > should be used for testing, itself a subjective evaluation. We all know > depth of field decreases in dim light because the pupil dilates, so > someone who might pass the test in bright light would fail if it's done in > poor lighting. OTOH, someone who wanted precise measurement might refract in dim light. -MT Dear Andrew, Subject: Lack of accuracy in Auto-refractors, Incorrect "accidental" over-prescription. Re: Checking these issues yourself. Re: Verifing you pass the standard DMV-Snellen in room illumination. While to a certain extent you should or might "trust" your OD -- it is also possible he made a "human" mistake, or some one copied some number incorrectly. How do you check. 1. you should have you own eye chart and check youself. (Download from www.i-see.org) 2. If you read the 20/40 line, and your OD tells you that you require a 2.0 or 3.0 diotper minus lens -- perhaps you should find another OD -- who will DISCUSS this issue with you -- rather than telling you are dumb, or "don't understand optics", or some other self-serving BS. 3. There are ODs who WILL SUPPORT you -- with this level of knowledge. You will find one at: www.chinamyopia.org In any event -- personal knowledge can be of help to you -- if you wish to do work to clear your vision from 20/60 to DMV standard. Obviously -- you have no choice but to take control -- given the statement by "Jan-OD" that the concept that the natural eye is dynamic "...must be destroyed". Equally, they judge anyone asking pointed questions about these issues in the same manner. But, as always enjoy these pleasant discussions on the nature of the natural eye's behavior when correcty tested -- and keep you mind open on the subject. Best, Otis Engineer > 2. If you read the 20/40 line, and your OD tells you that > you require a 2.0 or 3.0 diotper minus lens -- perhaps you > should find another OD -- who will DISCUSS this issue > with you -- rather than telling you are dumb, or > "don't understand optics", or some other self-serving > BS. If the the doctor says you need -2.00, it's because you told him -1.75 was blurry. You seem to think we make these numbers up. Are they lying to us? -MT > 2. If you read the 20/40 line, and your OD tells you that > you require a 2.0 or 3.0 diotper minus lens -- perhaps you Obviously -2.00 or -3.00 is way too high of a minus lens power for someone who is 20/40 unaided acuity. -1.00 is more like it. We don't want to use too much of that wretched minus after all! > In any event -- personal knowledge can be of help to > you -- if you wish to do work to clear your vision > from 20/60 to DMV standard. If someone is 20/400 say, and you correct them with just enough minus to achieve 20/40 and pass the DMV standard, that still isn't very good Otis. Would you like to drive around at night seeing 20/40-- most normal people wouldn't. Mike Tyner said >>Otis. Would you like to drive around at night seeing 20/40 More accurately Otis thinks it OK for everybody to be able to drive in any conditions after having passed "20/40 DMV" Night vision has to be worse than "20/40 DMV" Andrew > Dear Andrew, > Subject: Test conditions > Illumination has a provound effect on visual acuity. I thought the subject was "Reliability of autorefractors" > One man passes all legal requirements for vison, i.e., he reads 1.8 cm > letters at 6 meters -- in room illumination. [quoted text clipped - 3 lines] > > Hope this clarifies your question. This doesn't clarify anything. How does this relate to the question of reliability of autorefractors? > Best, > > Otis > Engineer Go away. > It seems my prescription changes with the autorefractometer used. I have > gone for several eye tests and my prescription has varied from the very best > at -2.25(Left Eye) and -2.75(Right Eye) to -2.50(Left Eye) and -3.25(Right > Eye). My question is what sort of lighting should the eye test be done in? > Because obviously the lighting would affect the results. Why don't you suppose that refraction changes? In fact, the refractometer provides constant illumination, it is a protected situation. Your refraction changes continuously in relation on how you use your eyes, consciously or unconsciously. > It seems my prescription changes with the autorefractometer used. I have > gone for several eye tests and my prescription has varied from the very > best at -2.25(Left Eye) and -2.75(Right Eye) to -2.50(Left Eye) > and -3.25(Right Eye). My question is what sort of lighting should the eye > test be done in? Because obviously the lighting would affect the results. Nobody should prescribe from an autorefractor. If your prescriptions come from an autorefractor, of course they will vary. In most cases they're simply used as an objective starting point, to cut down on the number of "one-or-two" questions you have to answer during the subjective refraction. In this sense, all that matters is whether the device consistently gives results close to the final prescription. Autorefractors are hooded so that room illumination is less important and more under the control of the instrument. Doctors have different opinions on whether the final subjective refraction should be done in low light or room light. -MT > In most cases they're simply used as an objective starting point, to cut > down on the number of "one-or-two" questions you have to answer during the > subjective refraction. In this sense, all that matters is whether the > device consistently gives results close to the final prescription. A shop assistant told me the autorefractometer readings can vary by a wide margin according to whether it's been recently serviced. Any truth in this? > Doctors have different opinions on whether the final subjective refraction > should be done in low light or room light. How much variation in dioptors can lightning account for? > How much variation in dioptors can lightning account for? Easily a half-diopter either way. Depends on the target and the amount of blur used as a cutoff. -MT > Doctors have different opinions on whether the final subjective refraction > should be done in low light or room light. Interesting statement. Can you please elaborate a little more? > Nobody should prescribe from an autorefractor. If your prescriptions come > from an autorefractor, of course they will vary. Mike..(and the rest of the general audience as well) Now that's a very interesting statement. In reading a few posts here it seems some really think autorefraction is sacreligious and only an adjunct to subjective (human-mediated) refraction. Well... Must be my eyes are goofy, or it's the combination of amblyopia, presybopia and nystagmus (oops, forgot astigmatism) that makes prescriptions resulting from 'subjective' refractions off by an estimated 2%, which, for me, using only my left eye for reading,driving, normal daily functions, is 2% too much. So: 1. I'm still using a pair of (scratched and needing replacement) lenses prescribed via autorefraction ONLY. Never had a problem reading with them, they're over 3 years old. 'Subjective' refractions, on the other hand, appear always to be problematic: three different O.D.'s (two at prestigious eye-care facilities in Chicago) penned three different (and non-acceptable) eyeglass prescriptions. 2. The problem may be in the fabrication of the lenses. Visually, I detect only a fingernails-worth of usable lens area (I pay for the whole lens...why doesn't the entire lens work as well as the fingernail-sized part?) 3. No, the lenses are not aspherically ground; that might improve things, if what I've read on several professional school sites indicates is correct. 4. The commentary I got during the refractions invariably put autorefraction in a very dismal light (pun intended). 5. If autorefraction is a poor substitute for human-mediated refraction... then why oh why do my autorefracted lenses perform flawlessly while the others inevtably have deficiencies? (defined as "they don't allow me to focus properly, except at the very tip-top of the (distance) lens) 6. Jargon. In all cases I attempted to elicit appropriate terminology from the O.D. so that I could effectively communicate my (very) subjective visual perceptions beyond "ONE. NO, go back to TWO. Wait. Uhhh." This was met with highly agitated and occassionally vitriolic responses from the (professional?) O.D.'s... What? They don't think anyone but an O.D. understands basic optics, visual acuity, depth-perception, low-light effects, high-refractive-index material usage vs other? And et cetera? 7. I'm not impressed so far, nor are the non-autorefracted lenses working as well as they 'should', IMNSHO. 8. S'gotta be the astigmatism?, which I -thought- was being taken into account during subjective refraction. 9. My curiosity question is, then: can you suggest anything (besides becoming an O.D. myself) which would a) result in an accurate and usable prescription b) result in lenses with a usable sweet-spot that covers substantially more than 5% of the lens c) take into account the aforementioned collection of maladies and 10. I don't think I'm the only person out here who has experienced this and wonders whether the bias against autorefraction is part and parcel of adhering to whatever litanies were taught. Thanks in advance, Terry B > Must be my eyes are goofy, or it's the combination of amblyopia, > presybopia > and nystagmus (oops, forgot astigmatism) that makes prescriptions > resulting from 'subjective' refractions off by an estimated 2%, which, > for me, using only my left eye for reading,driving, normal daily > functions, is 2% too much. "2% error" doesn't mean much if we don't know "2% of what?" Your eyes aren't "goofy", but yours _is_ a circumstance where we'll take any help we can get. > and wonders whether the bias against autorefraction is part > and parcel of adhering to whatever litanies were taught. No, it's experience. I see the results side by side several times a day. Modern autorefractors are reliable in this sense - if they're off from subjective refraction, the error will be close to the same each time (for a presbyope, anyway). IOW, they're more _consistent_ than they used to be, which makes them much more useful for before-and-after measurements in research. -MT > and 10. I don't think I'm the only person out here who has experienced > this > and wonders whether the bias against autorefraction is part > and parcel of adhering to whatever litanies were taught. It's all wrong, you won't find any kind of relief whatever. > It seems my prescription changes with the autorefractometer used. I have > gone for several eye tests and my prescription has varied from the very > best at -2.25(Left Eye) and -2.75(Right Eye) to -2.50(Left Eye) > and -3.25(Right Eye). My question is what sort of lighting should the eye > test be done in? Because obviously the lighting would affect the results. As MT said, autorefractors are very unreliable. They do not control for accommodation by the patient. They do not provide for any subjectinve input on clarity of vision. After all, vision is a subject perception-- it's not just about getting an image in clear focus on the retina although that is a large component of "good vision" (I can hear Andrew Judd warming up his keyboard right now). If you used the autorefractor in the eyedocs office then you already know that the surrounding illumination is reduced. This is good since it allows the pupil to dilate slightly and eliminates depth of field variability in refraction. Autorefractors also induce "instrument myopia" in many patients. For children, autorefractors are almost useless. I commonly see children who are +1.00 hyperopes register as -2.00 myopes because they accommodate during the testing. > For children, autorefractors are almost useless. I commonly see children > who are +1.00 hyperopes register as -2.00 myopes because they accommodate > during the testing. What age range do you classify children under? These numbers are my personal impressions using a handful of different autorefractors-- they are not a scientifically-validated. Young children-- ages 3-10, can vary wildly by several diopters from the actual subjective refraction quite easily. Teenagers can vary by a few diopters but generally less than younger kids. Adults less than age 50 can be register "more minus" in an autorefractor also quite easily but the tendency decreases as they get older (as their ability to accommodate decreases). Of course there are other factors that cause autorefractors to be inaccurate. Tear film prism, etc. These are not age dependent. Overall-- autorefractors are a nice piece of preliminary data to have during an exam but they are most often inaccurate. ==================== >> For children, autorefractors are almost useless. I commonly see children >> who are +1.00 hyperopes register as -2.00 myopes because they accommodate >> during the testing. > What age range do you classify children under? > If you used the autorefractor in the eyedocs office then you already know > that the surrounding illumination is reduced. This is good since it allows > the pupil to dilate slightly and eliminates depth of field variability in > refraction. Please can you tell me how much is the depth of field effect in dioptres? > Autorefractors also induce "instrument myopia" in many patients. Interesting. > For children, autorefractors are almost useless. I commonly see children > who are +1.00 hyperopes register as -2.00 myopes because they accommodate > during the testing. Interesting! if you do not know what instrument myopia is, that young hyperopes accommodate during refraction, or what depth of field effects are, then you are a fool and anyone who comes to you for vision care doesn't realize what a moron they are dealing with. you are a disgrace to all intelligent italians Dear Friends, Instrument myopia occurs when you you have verified that your distant vision is normal, i.e., PASSES all legal tests, by reading the Snellen. When you look through a "small aperture" "like a phoropter", and you measure -2.0 diopter -- then you have -2 diopters of "instrument myopia". Best, Otis Engineer > Instrument myopia occurs when you > you have verified that your distant [quoted text clipped - 5 lines] > -2.0 diopter -- then you have > -2 diopters of "instrument myopia". The word ''myopia'' in ''instrument myopia'' stands for the not needed/wanted accommodation for the nearby and is more or less used wrong if you do not know what you are talking about. People who are viewing in an instrument might easily have the idea they have to focus (accommodate) on an object nearby due to the fact the instrument is placed just in front of them. When people accommodate when they are measured they are moving to the ''myopic direction''. (or is the word ''shift'' instead of direction) However they could still be measured as being an hypermetropic, in this situation measured less hypermetropic then needed. A myopic in this situation is measured also with a myopic shift, so more myopic then the eye really should be measured. An emmetropic (not needing a correction for the distance) in this situation is due to the myopic shift measured as a (pseudo) myopic. In general, the younger you are the easier to accommodate, so Otis, you don't have to worry about having this ''instrument myopia" SignatureFree to Marcus Porcius Cato: ''Ceterum censeo Carthaginem esse delendam" In conclusion, I think that the "Otis therapy" should be destroyed Jan (normally Dutch spoken) > People who are viewing in an instrument might easily have the idea they have > to focus (accommodate) on an object nearby due to the fact the instrument is > placed just in front of them. Your profession is something. You use instruments who are not reliable, and still you use them. That's really difficult! > Instrument myopia occurs when you > you have verified that your distant [quoted text clipped - 5 lines] > -2.0 diopter -- then you have > -2 diopters of "instrument myopia". Dear Otis, Once again you demonstrate that your understanding of optics is inadequate. Instruments myopia is caused by the psychological impression of physical 'nearness' produced by having a person approach an optical instruments and look into it at a target. The brain believes it is looking at a visual target that is very close to it (it physically IS indeed close to it) and sends false signals to the ciliary muscle to accommodate even though it is not necessary to accommodate since the instrument contains plus lenses inside that project the visual target to optical infinity. See Jan's explanation. Instrument myopia is a bigger deal in younger people than it is older people because the "dynamic nature" of the adult eye is reduced by presbyopia. Stick to something you know about. Obviously not the eye or optics. Go build a bridge or build a better vacuum cleaner. > Instruments myopia is caused by the psychological impression of physical > 'nearness' produced by having a person approach an optical instruments and [quoted text clipped - 3 lines] > not necessary to accommodate since the instrument contains plus lenses > inside that project the visual target to optical infinity. So Bates was right when he said that the retinoscope should be used at least from 6 feet distance, otherwise the subject is disturbed. Why don't you invent one great refractometer which can be used at 10 feet? Are these instruments available now? Teach us. > So Bates was right when he said that the retinoscope should be used at > least from 6 feet distance, otherwise the subject is disturbed. Have you ever done retinoscopy at 6 feet? -MT > > So Bates was right when he said that the retinoscope should be used at > > least from 6 feet distance, otherwise the subject is disturbed. > > Have you ever done retinoscopy at 6 feet? > > -MT I know it's impossible. Nonetheless, he claims that. It seems Dr. Bates claims only impossible things... But indeed his system works, as far as I am concerned, and also my clients who practice it. > if you do not know what instrument myopia is, that young hyperopes > accommodate during refraction, or what depth of field effects are, then > you are a fool and anyone who comes to you for vision care doesn't > realize what a moron they are dealing with. you are a disgrace to all > intelligent italians Dear stupid friend, I asked you just because I KNOW what the answers are, and you are afraid I may expose you and your answers. Nobody comes to me for vision care, I am not a physician. I like to talk with intelligent people, Italians and abroad, who are doing their own self-treatment and exchange thoughts and experiences. Are you against free thinking? Perhaps you are a fascist. RM Said >> After all, vision is a subject perception-- it's not just about getting an image in clear focus on the retina although that is a large component of "good vision" (I can hear Andrew Judd warming up his keyboard right now). RM I would change that just a bit. Good eyesight has everything to do with a clear focus on the retina. But getting a clear focus on the retina is strongly related to having good vision. Good vision is for example related to our ability to judge distance, and control our emotional state so our judgement remains relatively constant. I find your comments about children and autorefractors very interesting. When NZ introduced identity card drivers licences over a one year period for all drivers and required them to have telebinocular sight tests (not autorefractors it is true) many people with otherwise good vision failed the tests. There was an expert comment at the time that people with a highly emotional disposition were unlikely to do well using this kind of test. I failed that test and so did a friend of mine. Go figure! Andrew > the tests. There was an expert comment at the time that people with a > highly emotional disposition were unlikely to do well using this kind of > test. I failed that test and so did a friend of mine. Go figure! So what they are requesting to people who fail? More glasses for the night? Don't you know that this will spoil their daylight vision as well? So Dr. Bates is not wrong after all when he writes that vision is largely mental? What are the ODs doing to cure this difficulty? > There was an expert comment at the time that people with a > highly emotional disposition were unlikely to do well using this kind of > test. I failed that test not surprising to me Dear Andrew, Subject: Auto-Refractors are seriously inaccurate. Below, Mike states that ODs should NOT rely on auto-refractors. Perhaps Mike is more "ethical" that others. What he suggests may not be respected by ODs who are attempting to meet the "standard" examination rate of 6 exams per hour. Unless you know this, you might be seriously over-prescribed. This is a good reason to check your vision on your own eye chart. Jamie has just checked his vision under room-illumination condition and sees 20/50 -- even though his "prescription" is -3.5 dipoters! Double checking YOUSELF is the first step in clering your vison -- under YOUR control. WHY AUTO-REFRACTORS -- AT ALL Since Mike declares thes devicies to be inaccurate, they why are they sold. Generally if you pay a lot of money for a piece of equipment -- you must use it. While Mike might be careful -- other might be less so. Let the buyer beware. Best, Otis _________ Nobody should prescribe from an autorefractor. If your prescriptions come from an autorefractor, of course they will vary. [Read seriously inaccurate -- by one to three diopters. ] -MT > Generally if you pay a lot of money for a piece of equipment -- you > must use it. While Mike might be careful -- other might be less so. No eyedoc prescribes from an autorefractor measurement. Do you think this is an example of some kind of eyedoc conspiracy--- buy a machine which prescribes too much of the wretched minus and use it on everyone? How foolish! >be respected by ODs who are attempting to meet the "standard" >examination rate of 6 exams per hour. You have no idea what the "standard examination rate" is for ODs. Again-- is this some sort of attack from you? Do you suggest we are all so sloppy that we just throw excessive (wretched) minus lenses on everyone and send them out the door? You are pathetic Otis. Go design a better vacuum cleaner. > Since Mike declares thes devicies to be inaccurate, they why are they > sold. There are several reasons. 1. Gives a starting point for checking refraction. If I'm a -10D, and the doctor starts with -1 and progresses by 1, then I'm going to be too worn out to be accurate by the time he gets to -10D. 2. Gives a rough idea for patients who will not cooperate. 3. Gives a rough idea for patients who can't see. After my retinal detachment, my doctor used an autorefractor because I had cataract in that eye. SignatureDan Abel Sonoma State University AIS dabel@sonic.net > 3. Gives a rough idea for patients who can't see. After my retinal > detachment, my doctor used an autorefractor because I had cataract in > that eye. Dan-- Just out of curiosity, what does someone who's been through your vision experience think of myopia prevention? Scott The explanation above of the autorefractometer is very disturbing. It looks to me that basically the autorefractometer method is inherently flawed. The accuracy of an eye test when this method is used is subject to the expertise and experience of the OD. I can recall now how 1 year after I was first prescribed glasses (they were something typical like -1.0D), I saw an OD who told me I needed bifocals. A few months later my vision did not seem right. Another OD told me I had been given an incorrect prescription. Now years later I am told I am ~ -3.5D. But as others have pointed out I can see - let's say 20/50 even in the type of lighting OD's use in their offices to test people. It is very difficult but I can do it. In really good natural lighting I can see 20/50 a lot easier. And I have not been trying to improve my vision for that long. And I may not even be taking the correct approach until now!!! Furthermore I do not need glasses to read - I am myopic. No OD has ever told me to only use my glasses for distant work or for poor lighting conditions. Why wear glasses when you don't need them? Something just does not smell right. My wife's co-worked is a member of a Chinese religious group. She has been for 7 years. The group considers their meditation practices to be very advanced. She has told me of numerous stories where people, shortly after they started their meditation work, by accident and quite spontaneously realized they no longer needed their glasses. Am I to believe that every one of these cases were just coincidences??? Too many loop holes in the argument. > The explanation above of the autorefractometer is very disturbing. It would be even more disturbing if OD's actually used the damn things to figure out prescriptions. Every OD here has already told you that they don't Scott I see the comet study group have used multiple observations with autorefractors and mydriatics to get refractions for at least the latest study on self esteem and myopia. Thoughts on that? >I see the comet study group have used multiple observations with > autorefractors and mydriatics to get refractions for at least the > latest study on self esteem and myopia. > > Thoughts on that? Hmmm.. yes.. why didn't the self-esteem measures correlate with degree of refractive error? Shouldn't there be a dose-response relationship? -MT Mike Tyner said >Shouldn't there be a dose-response relationship? Perhaps you are going too far Mike? Nurse can do all the refractions at school and the eye doctors would have more time for golf and so on? just kidding Andrew >Something just does not smell right. apparently you didn't read very clearly. no optometrist or ophthalmologist uses autorefractors to prescribe the final prescription. i think that has been explained multiple times. or do you ascribe to the Otis conspiracy theory? by the way, if your vision is 20/50 without glasses, you are not -3.50. somebody made a mistake somewhere. and by the way, if you are myopic, then you can take your glasses off to read as long as you can see comfortably. please put them on when you need to see clearly in the distance. you do not need a bifocal if it is comfortable to take your glasses off to read. it's nice to be a little near sighted when you become presbyopic. now you have had an optometrist tell you that. maybe they did before but you didn't understand. > apparently you didn't read very clearly. no optometrist or > ophthalmologist uses autorefractors to prescribe the final > prescription. i think that has been explained multiple times. or do > you ascribe to the Otis conspiracy theory? yes, she did not read very clearly, she is to blame. > by the way, if your vision is 20/50 without glasses, you are not -3.50. > somebody made a mistake somewhere. yes, mistakes are always made by somebody else!!! put the blame on them! > and by the way, if you are myopic, then you can take your glasses off > to read as long as you can see comfortably. please put them on when then why your colleague wanted to sell them a bifocal pair of eyeglasses? > you need to see clearly in the distance. you do not need a bifocal if > it is comfortable to take your glasses off to read. it's nice to be a > little near sighted when you become presbyopic. > > now you have had an optometrist tell you that. maybe they did before > but you didn't understand. yes, she does not understand. there is an explanation for everything except the truth! > Too many loop holes in the argument. This "science" is itself a loophole. Just look at the story of a good man like Dan Abel. He has suffered everything is there to suffer, and still he trusts these people. It's difficult for me to understand how this can be possible. It seems a matter of "spiritual martyrdom". Some individuals are more prone to suffer spiritually than others. >Some individuals are more prone to suffer spiritually than others. For instance: those who continue to read your posts. > > 3. Gives a rough idea for patients who can't see. After my retinal > > detachment, my doctor used an autorefractor because I had cataract in > > that eye. > Just out of curiosity, what does someone who's been through your vision > experience think of myopia prevention? It's really not a concept for me, especially the Otis version. He's real clear that you need to start it early. I was in fourth grade before my myopia was diagnosed, and it was already pretty bad at that time (I have no clue what the correction was, though). When I got my first glasses, I was just stunned. You mean, *that's* what the world looks like? I had no clue. SignatureDan Abel Sonoma State University AIS dabel@sonic.net > There are several reasons. > [quoted text clipped - 7 lines] > detachment, my doctor used an autorefractor because I had cataract in that > eye. You miss the most important: IT MANIPULATES PEOPLE.
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