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Medical Forum / General / Vision / December 2005Some people think theres something wrong with my eyes!
Two things: 1. Do I have presbyopia or not? My symptoms are in line with this condition that occurs most often at ages 35-40. I am a little younger than that at 23 but I have trouble seeing from near with glasses/contacts. I have +2.5 diopters of accomodation meaning I can barely see down to 16 inches with my glasses on, any closer and it becomes blurry. Forget seeing fine print with glasses. My nearpoint test is 20/40 with glasses. I guess my presbyopia would be mild accroding to the nearpoint snellen. However I can see much better from near with weaker glasses or without them. With contacts I use reading glasses to make things from near clear(er) 2. People keep saying my 20/30 BCVA with -5 glasses isnt "perfect" vision. I was talking to a lady and she knows many others not correctable to 20/20 either. I told her theres many factors that determine one's BCVA such as astigmastims, high order abberations, how bad your vision is, how much your pescription glasses minify, the shape and optics of your eyes and retina. Some people see better than 20/20, does this make those 20/20 abnormal? Why is it dictated that you "must" have perfect vision with(out) correction or something is "wrong" To my knowlege, I have no pathalogies. My entire family is in glasses and only my brother and sister get close to 20/20 with glasses, but brother is only a -1 with slight astigmastim and sisters about a -3 with slight astigmastim as well. I am much more myopic at -4.5 to -5 3. My online friend discussed wavefront RGP contacts. I know its true RGP contacts provide the sharpest vision so I have a good chance of achieving 20/20, especially with custom wavefront RGP contacts made to fit my cornea perfectly. This will reduce my dependancy on glasses but ill still need reading glasses over them for near work. I also dont know how comfortable they are but she says much more than your basic soft contacts which are a one size fit all. Aceman, with regard to your message: news:1132564078.875458.12510@f14g2000cwb.googlegroups.com... No doubt you'll be told that presbyopia (old-age vision) at age 39 is not highly possible. It might be useful to understand that the 20|XX nomenclature basically describes your visual accuity in terms of what particular lines of characters you can read on a standard chart at some standard distance (near or far). It would be helpful to know what your correction for distance is. Seems you are saying that you need -5.0 diopters for each of your eyes. Do you know if you require correction for some astigmatism? > I have +2.5 diopters of accomodation meaning I can > barely see down to 16 inches with my glasses on, any closer and it > becomes blurry. Forget seeing fine print with glasses. My nearpoint > test is 20/40 with glasses. Possibly you are in need of a second opinion from an O.D. or opthamologist. If your vision, at your age, or any other age for that matter, should not be correctable to any better than 20|40, it should be possible to know the reason(s?) for it. > I guess my presbyopia would be mild accroding to the nearpoint snellen. > However I can see much better from near with weaker glasses or > without them. If, as you have mentioned, your eyes are capable of accomdating through a range of 2.5 diopters, you should be able, with proper eyeglasses, to focus your eyes down to a close distance of 1/2.5M, which comes, in inches to about 16, as you have mentioned. Corrected, you should have the same visual accuity at 16 inches as you have at virtual infinity (e.g., 20 feet). > With contacts I use reading glasses to make things from near clear(er) To bring things at reading distance into sharp focus, hopefully. Clear could mean other things, like less foggy, for instance. > theres many factors that determine one's BCVA such as astigmastims, > high order abberations, how bad your vision is, how much your > pescription glasses minify, the shape and optics of your eyes and retina. I don't know what BCVA means (binocular corrected visual accuity?). sh.t, eyeglasses do not "minify". > My online friend discussed wavefront RGP contacts. I know its true > RGP contacts provide the sharpest vision so I have a good chance of > achieving 20/20, especially with custom wavefront RGP contacts made to > fit my cornea perfectly. Before undertaking higher-order solutions, it would be wise to know for sure that your eyes cannot be corrected by ordinary eyeglasses, and why. Decent inexpensive ordinary eyeglasses for five-diopter myopes are not beyond possibility. > ill still need reading glasses over them for near work. At your age, you should be able to read with the same eyeglasses you use for distance vision. Using "the Plus", as Otis recommends, namely using reading glasses with about two diopters positive sphere added to you distance correction, might make your reading more comfortable, and might possibly forestall myopic progression, if you have a tendency towards that. I am not an eye doctor, but I am not stupid. -- Dicky "No doubt you'll be told that presbyopia (old-age vision) at age 39 is not highly possible." presbyopia can come at any age, but its common starting in your late 30s "It would be helpful to know what your correction for distance is. Seems you are saying that you need -5.0 diopters for each of your eyes. Do you know if you require correction for some astigmatism?" my vision fluctuates but 7 months ago my pescription was -5.5 sphere, -.5 cylindar in OS and -5 sphere in OD correctable to 20/30 in each eye. He made me guess the 20/25 line and I got some right. I mean I can tell the difference between an F and an O but I guessed between an F and a P or an O and a C for example. I did read all of the 20/30 line rapidly and easily and missed none. "Corrected, you should have the same visual accuity at 16 inches as you have at virtual infinity (e.g., 20 feet)." only with bifocals or two seperate pairs of glasses. I dont do bifocals so I have a -3.25 pair I am using now as I type this. "I don't know what BCVA means (binocular corrected visual accuity?). sh.t, eyeglasses do not "minify"." best corrected vision accurity. Glasses DO minify at 2% each minus diopter, plus magnifies by 2% each plus diopter. Were talking 10% smaller thru my -5 glasses which is enough minification to easily make half a line difference. Give me contact lenses and ill be seeing most or even all of the 20/25 line. "it would be wise to know for sure that your eyes cannot be corrected by ordinary eyeglasses, and why." They cant. No optometrist was able to refract me better than 20/30. I still wonder how some people can see 20/20 I mean those letters are very tiny! Why? I believe its high order abberations. Do some reading on this "At your age, you should be able to read with the same eyeglasses you use for distance vision." itll make me more myopic and its much easier to read without correction anyway "No, by definition, you do NOT have presbyopia." the symptoms are like it. "If your BCVA at FAR distance is 20/30, then something is wrong. At your age you should see 20/15 best corrected. Yes, any time I examine a young person who can only get 20/20 best corrected, I take a close look, because I "expect" to find 20/15, so in a sense you could say 20/20 can be an "abnormal" finding." supposedly 20/20 is perfect vision. There are a number of people with very perfect optics capable of better than 20/20, many are emmetropes or low myopes/hyperopes. I would love to see 20/15 this is super, super clear! "It is dictated only in that the vast majority (probably over 90%) of young adults without ocular pathology are correctible to 20/15 vision. If you're in that age group and can't "get 20/15", I'd be looking for something. Sometimes we can't find it, but usually we can." then by definition most people have some sort of occular pathology, most likley high order abberations. Most eyes arent perfect. Please read this link: http://www.grendahl.com/wavefront/wavefront_system.html Some people have more of those, others have less. I have more than average because at night I can see a "glow" around lights and lots of small starbursts around the lights and several large starbursts that point for long distances. Its not as bad as some who got lasik. No surgury has been performed, I have virgin corneas, just more HOAs than some. "RGPs may well be a good solution for you" they are famous for providing exceptionally crisp vision. Some optometrists said they can give me plano RGPs than perform a refraction over me and see if my BCVA improves. If so, this will rule the fact I have a bunch of HOAs. > -5.5 sphere, -.5 cylinder in OS and -5 sphere in OD > correctable to 20/30 in each eye. > only with bifocals or two seperate pairs of glasses. I dont do bifocals > so I have a -3.25 pair I am using now as I type this. Yeah, I was never happy with bifocals. Well, it seems to me your eyes are different enough so your reading glasses could have different prescriptions for the two lenses. > Glasses DO minify at 2% each minus diopter ... That's sure news to me. My eyes have been as much as 5D apart, but I have never noticed that my eyeglasses have made things 10% smaller on one side. It seems to me that the effect might depend on how well the eyeglasses are fitted. There should be an optimum distance between the cornea and the inner surface of the lens. But it is doubtful if that fact, if true, is respected by eyeglass fitters in general. > No optometrist was able to refract me better than 20/30. I > still wonder how some people can see 20/20 I mean those letters are > very tiny! Why? I believe its high order abberations. Do some reading > on this. You have given a reference to a very fancy machine, namely http://www.grendahl.com/wavefront/wavefront_system.html No doubt high order aberrations are measurable in most eyes, but I will bet that they are usually not serious enough so that 20|20 acuity, or even 20|15, can be achieved in most cases with the usual corrections (sphere and cylinder). > > (Dicky said:) "At your age, you should be able to read with the > > same eyeglasses you use for distance vision." > itll make me more myopic and its much easier to read without > correction anyway. With myopic error of 5 or 6 D, you'll be reading pretty close. It is beginning to sound like you may have idiot-prescribed eyeglasses. Yes, I believe that it is a good idea not to try to read through the same eyeglasses as one uses for distance vision. Otis believes that too, I guess, assuming I understand what he is talking about. Sooner or later you will not be able to do it even if you want to. > by definition most people have some sort of occular pathology, > most likely high order abberations. Most eyes arent perfect. Please > read this link: (see above) Through my lifetime experience, I have come to believe that many, if not most, have imperfect eye doctors. For years, I have needed to contest approximately every other refraction, frequently having to pay for new lenses. Errors were typically a half-diopter. I had one idiot Dr. for several years who used to always say something like "with your eyes, I can only correct you to 20|30. In that office, the refractions were done by Dr.-trained technicians. One lady there could show me the 20|15 line through the phoropter. But she did not last. It is actually a much longer story than that. I have kept a log of my experience with eyeglasses for over 50 years. > at night I can see a "glow" around lights and lots of small starbursts > around the lights and several large starbursts that point for long distances. Well, either you are looking through naked quite myopic eyes or through ~ -5D eyeglasses. Either way, you will see some weird effects. Possibly you have some pathology that is not refractive. > No surgury has been performed That is a good way to keep it. > I have virgin corneas, just more HOAs than some. This HOA thing may simply be a sales ploy from some guy who has an expensive gadget that most eye guys can not afford. > Some optometrists said they can give me plano RGPs than perform > a refraction over me and see if my BCVA improves. If so, this > will rule the fact I have a bunch of HOAs. Well, I guess that an RGP is some kind of fancy contact lens. It certainly would seem that contact lenses would tell you if your problems have to do with the shape of your corneas. But, if that is all you want to find out, you do not need fancy ones. But, while you are at it, why not get some that correct your spherical refractive error as well as your astigmatism (and other possible signficant corneal irregularity)? -- Dicky "That's sure news to me. My eyes have been as much as 5D apart, but I have never noticed that my eyeglasses have made things 10% smaller on one side. It seems to me that the effect might depend on how well the eyeglasses are fitted. There should be an optimum distance between the cornea and the inner surface of the lens. But it is doubtful if that fact, if true, is respected by eyeglass fitters in general." you probably have special lenses or the lenses are different indexes or vertex distances to reduce anisometropia. Look at something large, like a tree without glasses then put them on. The tree is now clear and appears smaller in size. To me, its 10% smaller but high myopes have it much worse. "I will bet that they are usually not serious enough so that 20|20 acuity, or even 20|15, can be achieved in most cases with the usual corrections (sphere and cylinder)." With all the talk how much HOAs affect vision, especially at night, those do matter! Point in proof, I made a tiny pinhole in a piece of paper and placed it in front of my glasses and I could see all of the 20/25 line without very much trouble. The contrast improved quite a bit, something HOAs are famous for....reduced contrast. The letters became really black thru a pinhole. The minification my -5 glasses do make the 20/20 line too small unless I step closer so im 16/20 which is basically 20/25. Tilting my glasses does nothing so its not any undercorrection. "With myopic error of 5 or 6 D, you'll be reading pretty close. It is beginning to sound like you may have idiot-prescribed eyeglasses." 8 inches focal point at -5d "Errors were typically a half-diopter. I had one idiot Dr. for several years who used to always say something like "with your eyes, I can only correct you to 20|30. In that office, the refractions were done by Dr.-trained technicians. One lady there could show me the 20|15 line through the phoropter. But she did not last." wow whats your pescription? If he could only get you to 20/30 hes undercorrecting you by as much as -1 diopters! You should find an optometrist that says "which is better, one or two" not one who chooses himself, you need to choose. All my optometrists kept flipping lenses and the best one gave me 20/30. He kept trying to correct me better but HOAs arent correctable. "This HOA thing may simply be a sales ploy from some guy who has an expensive gadget that most eye guys can not afford." HOAs are a true thing and many people have about 10% HOAs. I probably have 20% or more. Did you know the human retina is capable of vision anywhere from 20/10 to better than 20/5? Theoratically, its possible to achieve 20/5 vision in some humans if you do away with all low and high order abberations and they have perfect retinas, corneas, lens, perfect optics. This is what a hawk sees! All humans with healthy retinas, corneas, eyes are capable of better than 20/15 vision. Heres some quotes I found from the internet: 20/12 vision approaches the theoretical limit that the human eye is capable of seeing. We rarely attain 20/12, or even 20/15 vision with glasses or contacts! Realizing that 20/20 does not represent perfect vision is important because many young healthy adults have visual acuities of 20/15 to 20/12. If optical aberrations in the eye could be eliminated, the theoretical limit of foveal acuity would be 20/12 for a small pupil and up to 20/5 for a dilated pupil. The theoretical limit of visual acuity is about 20/5. But current technology, including laser surgery, cannot correct for all of the eye's aberrations. Until recently, it was difficult to detect many of these flaws. With the emergence of new computer modeling approaches and optical technologies, however, researchers speculate that laser surgery will soon be refined to yield 20/10 in most patients. To succeed will require a unique melding of biology and engineering. There! Even a 20/20 eye has HOAs holding him back from 20/10 or better. I just have more HOAs than you. I have told my dad about getting custom wavefront RGP contacts but he does not believe in them and thinks its an expensive gimmic. I said I have a high likehood of achieving perfect 20/20 with them, a full 2 lines better than with my best glasses and 3-4 lines more than my other glasses. > [ ... ] > You should find an optometrist that says "which is better, one or two" > not one who chooses himself, you need to choose. They all say that. That is their game. Then they say "I have to believe what you tell me". They say that when you get the wrong prescription. > All my optometrists kept flipping lenses and the best one gave me 20/30. > He kept trying to correct me better but HOAs aren't correctable. Let me tell you this bit of personal experience. Very recently I got an IOL implant, on account of cataract. Several weeks after, the surgeon's tech checked my eye and said I'd need 0.5D, O.5D @ 75, but it was not time yet for new eyeglasses. With that I saw the 20|15 line. I need to see signs for night driving, so went to another eye doctor for a temporary lens. He said the best he could do for me was 20|25. When he was doing the "this ..., or this?" thing, I was looking at pretty much equal blur. He did his stuff three times, and got the following three results: 1.) -0.50, -1.25 @ 070 2.) -0.00, -0.75 @ 050 3.) +0.25, -1.00 @ 060 For some reason, he figured the last was the right one. I suppose he could have invoked variable HOA's but I don't think he knows about them. Well, anyway, nuts to him. Now I have had both eyes done, and eyeglasses prescribed (for reading and for night driving) by the techs in the surgeon's office. > All humans with healthy retinas, corneas, eyes are capable of better > than 20/15 vision. Even with my old retinas and new implants, I can do 20|15 with just a bit of correction. Get around mostly without glasses. Read fine with +1.25 Walgreens. > With the emergence of new computer modeling approaches and > optical technologies, however, researchers speculate that laser surgery > will soon be refined to yield 20/10 in most patients. To succeed will > require a unique melding of biology and engineering. I'd recommend going very slow on that. There is a considerable potential downside to laser surgery, any eye surgery. > I just have more HOAs than you. I am tempted to say HOAgwash! > I have told my dad about getting custom wavefront RGP contacts but he > does not believe in them and thinks its an expensive gimmic. I said I > have a high likelihood of achieving perfect 20/20 with them, a full 2 > lines better than with my best glasses and 3-4 lines more than my other > glasses. You might do well with contacts, particularly if you do athletics. But I would bet that the more expensive ones will not be much better for you than the run of the mill. You might find that you do not like them. They are a big pain in the a.s, you know. Mostly they are for vain ladies. Well, Patient Abel does not think I should be giving advice. But I think that I can reasonably say that, if it were a matter in my family, I would thoroughly investigate the possibility of attaining 20|20 or better with ordinary eyeglasses. And, if that were not possible, I would like to hear a better explanation than HOA's. I guess maybe now would be a good time for some of the good eye doctors to step forward and throw some light on this matter of HOA's. Now I see your most recent post: news:1132717221.540421.75640@g43g2000cwa.googlegroups.com... It could be that you are being hustled. Even if you need contacts for your particular problem (assuming you do in fact have that problem), you do not need top-of-the line contacts to find out if they are good for you. -- Dicky Not an eye doctor. > Several weeks after, the surgeon's tech checked my eye and said I'd > need 0.5D, O.5D @ 75, but it was not time yet for new eyeglasses. > With that I saw the 20|15 line. Oops... -0.50D, -0.50D @75 > > I have told my dad about getting custom wavefront RGP contacts but he > > does not believe in them and thinks its an expensive gimmic. I said I [quoted text clipped - 12 lines] > investigate the possibility of attaining 20|20 or better with ordinary > eyeglasses. > It could be that you are being hustled. Even if you need contacts for your > particular problem (assuming you do in fact have that problem), you do not > need top-of-the line contacts to find out if they are good for you. I wore contacts for 10 years. I am not a vain lady. I resisted them for decades, but was finally convinced that I needed them for best vision, not because I looked better in them. There are different sorts of contacts. Some are more expensive than others because they work differently. RGPs may be more expensive, but they aren't just "top of the line" or a gimmick. I don't need contacts anymore. I don't wear them anymore. Contacts are the way to go for some people. I recommend them highly for those people. I'm no longer one of those people. I had cataract surgery in both eyes, and occasionally wear glasses.  SignatureDan Abel dabel@sonic.net Petaluma, California, USA "They all say that. That is their game. Then they say "I have to believe what you tell me". They say that when you get the wrong prescription." then they are incompetent and need to go back to training school if they cant even properly refract their patients! "He said the best he could do for me was 20|25. When he was doing the "this ..., or this?" thing, I was looking at pretty much equal blur. He did his stuff three times, and got the following three results:" hes incompentant, plain and simple. Tell him that the refractions he was doing was not helping to resolve your 20/25 UCVA into 20/15 BCVA. Ask to be refracted by autorefractor so he can get an idea of your minimal residual pescription for night driving. "Even with my old retinas and new implants, I can do 20|15 with just a bit of correction. Get around mostly without glasses. Read fine with +1.25 Walgreens." your 20/25 UCVA is better than my 20/30 BCVA. I get around fine with 20/40 vision which my -4.25 glasses give, yes they undercorrect me by about half a diopter but my pescribed -5.5 glasses make me dizzy and make things blurry from nearer. They are too strong(now) because my eyes have become less myopic(pseudomyopia resolving) I need to get a new manual(and cycoplegic) refraction then ill order glasses based on my cycoplegic refraction since this is my real myopia. My brother is only a -1 with -.5 astigmastim so he gets around fine with 20/60 UCVA. Glasses dont make a big difference(20/20 to 20/25) so he only wears them for driving. you have a small amount of myopia left so this is why you get by fine with +1.25 readers. With my contact lenses in, I find things from near very clear with +2.5 readers. I can read clearly with +1.25s too if I do a little accomodating. You see 20/15 because you dont have alot of HOAs in the way. Most of them are on the cornea itself but whatever HOAs and imperfectations your natural lense had is gone. Your IOLs are of highest quality so they give you very clean, sharp vision. "I'd recommend going very slow on that. There is a considerable potential downside to laser surgery, any eye surgery." correct. My next step is to try those custom zwave contact lenses. My friend(s) have told me this will provide me with better vision than anything else out there, including any refractive surgury. They are supposed to be much easier to tolerate than soft lenses and forgiving of dry eyes. I will wear those lenses as much as I can and if they are comfortable, ill wear them full time. I will need a 2nd pescription with less minus power for around the house and the computer. Ill wear the full power when I go out and if theres any reading to do, ill bring my reading glasses. By the time I get cateracts, technology will be so advanced ill be seeing perfect with IOLs in. "I am tempted to say HOAgwash!" HOAs are a fact otherwise RGP lenses wouldnt provide much better vision than glasses and soft contacts. I have shown my topography to several doctors and they agreed I have HOAs and irregular astigmastim. "But I would bet that the more expensive ones will not be much better for you than the run of the mill" I can not tolerate soft contacts, they dry ny eyes out. RGP contacts arent supposed to because they do not absorb your tears and evaporate them. I cant get 20/20 with soft contacts either. "You might find that you do not like them. They are a big pain in the a.s, you know. Mostly they are for vain ladies." RGP contacts are superior to the soft kind. I got an 18 year old friend who wears them and he looooooooooves them and can see near the bottom of the snellen with those. I am not vain but for a change, I want to reduce my dependancy on glasses! "I would thoroughly investigate the possibility of attaining 20|20 or better with ordinary eyeglasses. And, if that were not possible, I would like to hear a better explanation than HOA's." There is NO way im gonna see 20/20 with glasses. I cant even pinhole myself to 20/20! Many of my HOAs are in the center of my vision. I see 20/30(left) 20/30 to 20/40(right) and with a pinhole I can see all of 20/25 sharply in left and half of the 20/25 in right. Tilting my glasses does nothing so I am not undercorrected with those. Its a HOA issue which pinholes bypass some of. My mom's BCVA is equal to mine and my dad's is 20/25 only because his glasses magnify things. Even my brother cant be fully corrected to 20/20! I dont think its that easy to see 20/20 with or without correction. This is the pinnicle of perfect vision! 20/40 is sharp vision, 20/20 would be VERY, VERY sharp vision(sorry lasik guys, your 20/20 is different) "you do not need top-of-the line contacts to find out if they are good for you." soft contacts suck! I could get regular RGP but they wont fit my irregular cornea correctly so I need custom zwave contacts. "I wore contacts for 10 years. I am not a vain lady. I resisted them for decades, but was finally convinced that I needed them for best vision, not because I looked better in them." you probably were a high myope and hated the cokebottle glasses and how they make things considerabily smaller. > ... soft contacts suck! I could get regular RGP but they wont fit my > irregular cornea correctly so I need custom zwave contacts. Looks like you have got your heart set on the custom zwave jobs. Dad called the doctor for some questions. 1. He says he can give me a multifocal lense for my presbyopia. He says I will need to hold books half meter from me to see them cleatly. Then whats the point of multifocal? I can see half meter with regular contacts and full power glasses. Multifocal contacts cost more and if I dont like em I lose $400! Ill just get regular contacts and take my reading glasses with me so I can read from 12 inches away. 2. He says he can give me a toric RGP if I have astigmastim? I thought you didnt need a special RGP and that it automatically corrected my astigmastim? How hard is it to correct astigmastim with a RGP lense anyway? 3. how exactly do you remove a rigid lense? suction cap? Any other way to remove? 4. Theres some confusion about vertex distance. I told him the ratio is 1.25 and he said thats about right. This means id need -4 contacts if my glasses are -5. -4.5 contacts will make things blurry. 5. he says I should see much better with those RGP than glasses. I will only if I get the right pescription, not too strong and if it corrects my astigmastim and HOAs. http://www.racerocks.com/racerock/firstnations/gazette.jpg http://img305.imageshack.us/img305/6809/newspaper27vx.jpg The top image is what I see without correction or a low minus lense. The bottom image is what I see with my full pescription correction to make me plano. If I hold the newspaper at arms length, its clear. However I can hold it much closer if I reduce the minus correction. I can not get things close enough to see fine print with full correction. Therefore if I got contact lenses that fully correct me, I will still need reading glasses. I either have early presbyopia at age 23 or I have accomodative dysfunction. > "I wore contacts for 10 years. I am not a vain lady. I resisted them > for decades, but was finally convinced that I needed them for best > vision, not because I looked better in them." > > you probably were a high myope and hated the cokebottle glasses and how > they make things considerabily smaller. That was part of it. Mainly it was the five years that I was -10d in one eye and plano in the other. My doctor promised me that glasses would make me see double, and they did. Seeing double is not a good thing. Contacts don't have that problem. SignatureDan Abel dabel@sonic.net Petaluma, California, USA > > Glasses DO minify at 2% each minus diopter ... > [quoted text clipped - 5 lines] > fact, > if true, is respected by eyeglass fitters in general. That's interesting. Are you just blind in one eye, or both? :-( > Yes, I believe that it is a good idea not to try to read through the > same eyeglasses as one uses for distance vision. Otis believes that I'm an old guy, too. I didn't used to be, though. I used to be able to do a lot of stuff that I can't anymore. > Through my lifetime experience, I have come to believe that many, > if not most, have imperfect eye doctors. For years, I have needed to > contest approximately every other refraction, frequently having to pay > for new lenses. Errors were typically a half-diopter. I had one idiot > Dr. for several years who used to always say something like "with They're all quacks. Don't go to them. They'll be a lot happier if you don't. I'm pretty easy to get along with. Sometimes a doctor doesn't work out. I change doctors. I don't continue to see them for "years". > Well, I guess that an RGP is some kind of fancy contact lens. It > certainly would seem that contact lenses would tell you if your problems > have to do with the shape of your corneas. But, if that is all you want > to find out, you do not need fancy ones. You do an awful lot of "seeming". I'm not sure that you and Otis are very qualified to give medical advice. I post a lot here. I post about my own experiences as a patient. I don't tell people what to do. I'm not qualified. I tell them to see an eye doctor. SignatureDan Abel dabel@sonic.net Petaluma, California, USA said to me: > [ ... ] > You do an awful lot of "seeming". I'm not sure that you and Otis are > very qualified to give medical advice. I am qualified to say how things seem to me. Otis is on his own. > I post a lot here. I post about my own experiences as a patient. Could you consider yourself a consumer of medical services? "Consumer" implies a bit gutsier stance. "Patient" is very passive and accepting. You might consider the role of "patient advocate". > I don't tell people what to do. I'm not qualified. I tell them to see > an eye doctor. Deep down, it seems you are a teller, albeit admittedly unqualified. Could you tell them which one to see? -How to know the difference between a good one and a not-so-good one? That would be a useful post! -- Dicky well this is just in. I showed a prominent doctor near me my topographies and he says I have irregularities. I was right, my high order abberations is holding me back. If my corneas were more perfect I would be seeing 20/25 and if they were nearly perfect, id see 20/20! He told me I should experience much better vision than I ever have with custom zwave RGP contacts. I see no reason I wont achieve 20/20(or even better!) with those if theres nothing wrong with my eyes or retina. I can be pinholed to 20/25 and thats WITH the minification glasses give me! Those contacts dont minify so letters wont be as tiny. There are people seeing 20/20 in spite of glasses minification but the higher their pescription, the fewer will see 20/20 due to the artificial limits of glasses due to minification. I know one lady whos -10 and shes at the point where she can no longer see 20/20 with glasses but with contacts 20/20 is easy to see. I know for a fact my eyes are capable of 20/25 with -5 glasses and a pinhole. Due to glasses minification, they cost me half a line. Higher pescriptions may cost a line, a line and a half or even more! I know one guy who had a very high pescription and was seeing 20/40 with glasses, 20/25 with RGP contacts! glasses+pinhole probably wont be as sharp as RGP contacts. I am guaranteed to see 100% of the 20/25 line easy and clear and nearly guaranteed to see 20/20 as well. Depending how well those RGP reduce my HOA's, I may actually see better than 20/20! > Two things: > > 1. Do I have presbyopia or not? My symptoms are in line with this > condition that occurs most often at ages 35-40. I am a little younger > than that at 23 but I have trouble seeing from near with > glasses/contacts. No, by definition, you do NOT have presbyopia. I have +2.5 diopters of accomodation meaning I can > barely see down to 16 inches with my glasses on, any closer and it > becomes blurry. Forget seeing fine print with glasses. My nearpoint > test is 20/40 with glasses. Something is wrong with your glasses, or you have "accommodative insufficiency". However I can see much better from > near with weaker glasses or without them. With contacts I use reading > glasses to make things from near clear(er) Sounds like you've found a solution on your own. > 2. People keep saying my 20/30 BCVA with -5 glasses isnt "perfect" > vision. I was talking to a lady and she knows many others not [quoted text clipped - 3 lines] > and optics of your eyes and retina. Some people see better than 20/20, > does this make those 20/20 abnormal? If your BCVA at FAR distance is 20/30, then something is wrong. At your age you should see 20/15 best corrected. Yes, any time I examine a young person who can only get 20/20 best corrected, I take a close look, because I "expect" to find 20/15, so in a sense you could say 20/20 can be an "abnormal" finding. Why is it dictated that you "must" > have perfect vision with(out) correction or something is "wrong" > To my knowlege, I have no pathalogies. My entire family is in glasses > and only my brother and sister get close to 20/20 with glasses, but > brother is only a -1 with slight astigmastim and sisters about a -3 > with slight astigmastim as well. I am much more myopic at -4.5 to -5 It is dictated only in that the vast majority (probably over 90%) of young adults without ocular pathology are correctible to 20/15 vision. If you're in that age group and can't "get 20/15", I'd be looking for something. Sometimes we can't find it, but usually we can. > 3. My online friend discussed wavefront RGP contacts. I know its true > RGP contacts provide the sharpest vision so I have a good chance of [quoted text clipped - 3 lines] > know how comfortable they are but she says much more than your basic > soft contacts which are a one size fit all. RGPs may well be a good solution for you, but I'd still want to know the reason you aren't getting 20/20 or better. I suspect a bad refraction, and would recommend you discontinue contact lens wear for a week prior to your next eye exam in order to get the best refractive result. w.stacy, o.d. As discussed at alt.lasik.eyes, you need to get your eyes tested properly. Your idea of your prescription being -4.5 and -5 was based on your farpoint without glasses on - not remotely reliable. You may well be overvorrected, have accommodative insufficiency, convergence insufficiency, form fruste keratoconus, congenital cataract, Stargarde's syndrome or any of a litany of other problems ( that will give you something else to worry about). Online advice will be flawed due to lack of any real clinical findings, sort of like the mother of a patient I saw yesterday who mentioned she may have keratoconus, but probably not as it wasn't getting worse. Her doctor lead her to believe she would go blind if it were KC, so as she wasn't blind, it mustn't be??? Can't work out the logic there somehow!!! The thing was she had not had topography and no clear diagnosis had ever been made. Spend a little money, go see a good optometrist or ophthal who will assess your problem and give you a correct diagnosis and treatment. dr grant > Two things: > [quoted text clipped - 8 lines] > near with weaker glasses or without them. With contacts I use reading > glasses to make things from near clear(er) At 23, you are too young to have presbyopia, which means "old eyes." The technical term is "accommodative insufficiency." > 2. People keep saying my 20/30 BCVA with -5 glasses isnt "perfect" > vision. I was talking to a lady and she knows many others not [quoted text clipped - 8 lines] > brother is only a -1 with slight astigmastim and sisters about a -3 > with slight astigmastim as well. I am much more myopic at -4.5 to -5 I'm sure you can figure out why 20/20 is considered the "standard." It's based upon the normal distribution of visual acuity. Scientists who have studied these things say that the average eye is able to resolve a visual angle equivalent to 20/6 based upon the retinal mosaic. Therefore, the optics of the eye appear to be the limiting factor. Of course, retinal and neurological defects can also cause subnormal acuity. Obviously, being born with defective optics is a much different scenario and has different implications than an acquired disease of the retina of optic nerve. > 3. My online friend discussed wavefront RGP contacts. I know its true > RGP contacts provide the sharpest vision so I have a good chance of [quoted text clipped - 3 lines] > know how comfortable they are but she says much more than your basic > soft contacts which are a one size fit all. Yada, yada, yada. There is currently no such thing as a commercially available RGP lens based upon wavefront optics. There is something with a catchy name having the word "wave" in it that confuses people. I think you need to find a good optometrist who is proficient in RGP lenses and pay for a consultation. The doctor may, or may not use the software with the confusing name. If you are truly wanting the comfort of a soft lens with the advantages of an RGP, you will want to check out semi-scleral lenses such as Macrolenses. A trial fitting should convince you of this without being obligated to purchase the lenses. Unfortunately, with some lenses such as those created using software with the confusing name and produced by a lab far, far away, you will have to pay for the lenses before getting to try them first. By the way, you keep repeating that the vertex correction for -5.00 is 1.25 diopters. It is not. It is 0.25 diopters. DrG "At 23, you are too young to have presbyopia, which means "old eyes." The technical term is "accommodative insufficiency." either way, this means some myopia is my friend and is whats keeping me out of reading glasses. I want to remain myopic but less than the -5 I am now. -2 sounds nice right now! "I'm sure you can figure out why 20/20 is considered the "standard." It's based upon the normal distribution of visual acuity. Scientists who have studied these things say that the average eye is able to resolve a visual angle equivalent to 20/6 based upon the retinal mosaic. Therefore, the optics of the eye appear to be the limiting factor. Of course, retinal and neurological defects can also cause subnormal acuity. Obviously, being born with defective optics is a much different scenario and has different implications than an acquired disease of the retina of optic nerve." I have researched this and you are right. Its agreed most eyes are capable of better than 20/10 if they have no occular pathalogy. Yes thats true that 20/20 is the standard of "normal" vision but a good percentage of people dont see this well without correction and many even with! My mom and dad dont get 20/20 with correction. My brothers only a -1 and he can see half of the 20/20 line with BCVA. You got that right, the optics of the eye limits almost everyone from seeing their best that the retina is capable of. I just happen to have a little more optical limitations than "average" ". There is currently no such thing as a commercially available RGP lens based upon wavefront optics. There is something with a catchy name having the word "wave" in it that confuses people." zwave custom RGP comes to mind. They say its wavefront customized to each individual eye so you will see better than you ever did with glasses! "I think you need to find a good optometrist who is proficient in RGP lenses and pay for a consultation." Thats what I want to do. I also want a throught eye exam to find out the bottom of my 20/30 BCVA and my "presbyopia" and learn about my eyes. There probably is nothing wrong but it would be good to know. "A trial fitting should convince you of this without being obligated to purchase the lenses. Unfortunately, with some lenses such as those created using software with the confusing name and produced by a lab far, far away, you will have to pay for the lenses before getting to try them first." yea thats $300 for both lenses and if I dont like em, too bad. "By the way, you keep repeating that the vertex correction for -5.00 is 1.25 diopters. It is not. It is 0.25 diopters." Its not 1.25 diopters, its 1.25 ratio. Multiply your contact pescription by 1.25 to arrive at your glasses pescription. My -3.25 contacts multiplied by 1.25 are equal to -4 glasses(-4.06 actually) I own a pair of -3.25 glasses and -4.25 glasses and my -3.25 contacts give me very nearly the correction my -4.25 glasses do. I get MUCH more correction vs. my -3.25 glasses. I have worn -4 multifocal contacts before and they gave me equal vision to my -5 glasses. -4.75 contacts would be comparable to -6 glasses and overcorrect me by +1 diopters. I have a friend who wears -4.75 contacts and her glasses pescription is -6. We both took our glasses off and I could see several feet further than she could. > zwave custom RGP comes to mind. They say its wavefront customized to > each individual eye so you will see better than you ever did with > glasses! That is not so. If that is the case, what aberrometer is going to be used to capture the wavefront information? That system uses information from topography and not aberrometry. I would be a little more critical of this if I were you. > Its not 1.25 diopters, its 1.25 ratio. Multiply your contact > pescription by 1.25 to arrive at your glasses pescription. My -3.25 [quoted text clipped - 7 lines] > and her glasses pescription is -6. We both took our glasses off and I > could see several feet further than she could. Again, you are incorrect. Please examine your premises. DrG "That is not so. If that is the case, what aberrometer is going to be used to capture the wavefront information? That system uses information from topography and not aberrometry. I would be a little more critical of this if I were you." Topography just measures the aberrations and everything else on the surface of your cornea. A wavefront abberometer measures all abberations. Newer materials and technology not only allow us to correct these prescriptions, they can even give you vision that is superior to that achieved with eyeglasses. "Again, you are incorrect. Please examine your premises." If you gave me a -2.75 contact, you will find out that my myopia was reduced by 3.5 diopters. giving me -3.25 contact will reduce 4 diopters of my myopia. I would be plano with a -4 contact and any higher and you may as well hand me bifocals. I know this because those are the powers I have sampled. I have -3.25 glasses and -2.75 contacts correct me more than -3.25 glasses. With the -2.75 contacts and -3.25 glasses over them, I cant see a thing from near and even distance is blurred. I put +2 reading glasses over them and its clear in the distance. With +1.5 readers, distance is still clear but near gets blurry. I can see 20/100 without too much trouble with -2.75 contacts but I can barely see 20/100 with -3.25 glasses. Many of my friend's contacts have been correctly compenstated for vertex distance. This lady has a -6 glasses pescription and wears -4.75 contacts. Another is -3 contacts and -3.75 glasses. Feel free to disagree, but howcome my own wearing of contacts as a patient agrees with the 1.25 ratio? Multiply contact pescription by 1.25 to arrive at glasses Ace, I appreciate your comments, except that sometimes you are wrong. You stated that the RGP contact lenses you were seeking were generated from wavefront data. That is not correct. They are generated from topography, there is a difference as you have pointed out. Also, there is a difference between the vertex correction and other factors which enter into the final contact lens prescription. Those "other factors" include the mismatch between the corneal curvature and the base curvature of the contact lens, and the induced power created by that mismatch. This may not be constant from one contact lens to the other, or from one person to another. DrG Guess I must have been confused about topography. Would it make a difference if they use wavefront vs. topography to make your custom RGP contacts? I guess the 1.25 ratio applies in average cases. If I am achieving a reduction of -4 diopters of myopia with -3.25 contacts, would this mean I have steep corneas so this makes the contacts curve more and therefore increase its minus power? Wow so now we have so many factors in determining the contact pescription that mistakes are bound to occur. They overcorrected my mom so she went back for a lower minus power. Someone who could still accomodate wouldnt even notice the overcorrection. I know one lady whos a -8 in glasses and she also got -8 contacts and her eyes have been getting worse rapidly ever since she switched to contacts. I see mistakes happen all the time. Another lady got -3 contacts but she told me her -3 glasses are too weak. I said of course they (might)need to be -3.75 but her -3 glasses will be fine around the house and using the computer. Mike, the calculator does not take into account the factors such as base curve and corneal curvature which DrG said. It does not apply for most people and definately NOT for me. I entered in -5 glasses and it wants to give me between -4.5 and -4.75 contacts. My -6 friend wears -4.75 contacts! There may be some cases where a -5 guy would need -4.75 contacts, spherical equivalent plays into account, along with the curve of your cornea. A good rule of thumb is that your contact pescription should be lower than your glasses pescription, especially if you have more than a little myopia! This guy who got lasik was -6 in contacts but he seemed supprised to learn he was refracted as -7.5 in glasses! 6 times 1.25 is 7.5 so it makes perfect sense! There is indeed a difference between topography and aberrometry. Most topographers are based on the placido disk, which is a series of light and dark rings projected onto the cornea, captured by video, converted into datapoints which are then used to "render" an approximation of the contour. Aberrometry, on the other hand, sends rays of light in the form of laser beams into the eye at many different points. The deviation of each beam is then measured as it comes back out of the eye. This system measures the true optical performance. As of now, there is no commercially available contact lens based upon wavefront aberrometry. On the other hand, there are numerous software programs available for designing contact lenses from raw topographical data. Most topographers have them included in the software. Only one step is needed to determine the actual power of the contact lens that is needed for each individual eye. It is called an over-refraction. This simple, but additional step is all that is needed to prevent over- or under-estimating the correct lens power. DrG > contour. Aberrometry, on the other hand, sends rays of light in the > form of laser beams into the eye at many different points. I think it's a single point-source, sampled with an array of receiving apertures. -MT > > contour. Aberrometry, on the other hand, sends rays of light in the > > form of laser beams into the eye at many different points. [quoted text clipped - 3 lines] > > -MT There are three basic types of aberrometers: Tscherning, Schack-Hartmann, and ray tracing. Tscherning uses an array of lenslets to split the projected laser beam. Schack-Hartmann uses a single wavefront with an array of detectors. Tracey Technologies uses a single laser beam in a sequential pattern. The point is that many different points of the eye are measured. DrG Dear Ace, I feel some empathy towards you since, when I was adolescent, I was called "Ace". The reason was that there was, at that time, a baseball player with my same last name, who was called "Ace". The reason for calling me that was that, when a baseball was thrown at my head, it would hit me for sure, because I was not able to see it coming. So, you see, that name was very funny when applied to me. Everybody had a good time! But that was before "Dr. Leukoma" and Mike Tyner were born, and Dan Abel was still wearing knickers. There was no possibility of contact lenses, and nobody talked about wavefronts when it came to eyeglasses. Bates had come and gone. Some kids were exposed to elementary optics in high-school physics. For instance, I was. The people who fitted eyeglasses talked a language that a student of high-school physics could understand. In connection with the discussion here, which I flatter myself to believe that I understand vaguely, I must wonder if there is any consideration to refractive-index matching when it comes to canceling the effect of corneal irregularities, assuming they are on the outside. That would mean planting a r.i.-matching fluid under each contact, and wondering how long it would take for it to dilute down or irritate the cornea. Maybe some of the eye doctors know why that idea is impractical. My lady thinks she would like a Wave Radio. I have a bunch of radios some of the hi-fi kind, and they sound good to me. Do you think that a Wave Radio would be any better? -- Dicky "Ace" Adams > In connection with the discussion here, which I flatter myself to believe > that I understand vaguely, I must wonder if there is any consideration to > refractive-index matching when it comes to canceling the effect of corneal > irregularities, assuming they are on the outside. That would mean > planting > a r.i.-matching fluid under each contact As it turns out, the RI's of cornea, tears, and gas-perm plastics are all pretty much the same. So tears work pretty well as an "r.i.-matching fluid." This means that theoretically, gas perm contacts _are_ correcting all the corneal irregularities (though they may induce a little spherical abb of their own). But wavefront plots the resultant of _all_ the refractive surfaces, not just the cornea. -MT "It is called an over-refraction. This simple, but additional step is all that is needed to prevent over- or under-estimating the correct lens power." I read about this and it means you keep giving plus power till the patient's vision starts showing myopic blur. An easier way is to estimate a bit low and add more minus to bring him to plano. Those who can accomodate may not notice the overcorrection. I would rather be undercorrected and have more minus added to bring me to plano. "It could mean your true spectacle refraction is -350 and you just like overcorrection in glasses." actually its the opposite. I like undercorrection because it relaxes my eyes and makes things from near(er) more clear. I was manually refracted at -5.5(left) and -5(right) but I believe I had pseudomyopia and my real refraction is definately lower. Right now I can see at my BCVA with my older -5 glasses on the left eye. Ditto for a -4 contact. I really need to get a cycoplegic refraction soon. I am quite sure I still have some more pseudomyopia.(this can also partially explain my accomodative dysfunction) "And I know of a study where 36 children wore excess minus and were compared to 36 who were refracted correctly. It didn't cause any additional myopia." The study would have been much better if one eye was overcorrected and the other left at plano. There are people out there that purposely induce more myopia by overcorrecting themselves. You can read this on some message boards. I dont understand why they want worse eyes but thats another topic entirely. "Then we should stop using it? It works for me, several times a day, confirmed by overrefraction." It doesnt apply for me nor many of my friends. "Then the -600 is too much or the -475 is not enough." she sees her BCVA with both solutions. Her UCVA is worse than mine, confirmed by removing our glasses and reading a large sign, she had to move closer than me. I tried her glasses and they are sure strong. "If I had a patient with -600 contacts who overrefracted zero, and I made glasses with -750, I'd expect to have the glasses thrown back at me." try overrefracting his -7.5 glasses. This topic still confuses many people and is subjected to much debate. There are some that will argue the conversons of vertex distance while others will argue they are wrong. I think the best answer is theres other factors that can cause a derviation from the 1.25 ratio. The shape and steepness of one's cornea, the brand of contacts, how dry someone's eyes are, how much someone can accomodate, the spherical equivalent, etc. I would not be supprised if one -5 guy needed -4.25 contacts while another -5 guy only needed -3.75 contacts. This is a tricky subject where results vary slightly case by case basis. The 1.25 ratio is a good estimate based on averages but there will be people that just need more or less than that. My moms eyes are dry so her contact power is a little more than what someone with moist eyes would need. The shape of the cornea may also be playing a factor as is the vertex distance of her glasses. > I read about this and it means you keep giving plus power till the > patient's vision starts showing myopic blur. An easier way is to > estimate a bit low and add more minus to bring him to plano. Those who > can accomodate may not notice the overcorrection. I would rather be > undercorrected and have more minus added to bring me to plano. After a few years of doing it, I found that adding plus to blur is more reliable, particularly with younger people. Of course I'm happy for anyone else to do it your way, because it leads to more mistakes and makes me look better. :) > "It could mean your true spectacle refraction is -350 and you just like > overcorrection in glasses." [quoted text clipped - 3 lines] > refracted at -5.5(left) and -5(right) but I believe I had pseudomyopia > and my real refraction is definately lower. "Pseudomyopia" and "liking overcorrection" are essentially the same thing. It's _while_ you're being tested that you "like overcorrection." Many folks do. Then most of them find the glasses hard to wear. > "And I know of a study where 36 children wore excess minus and were > compared [quoted text clipped - 3 lines] > The study would have been much better if one eye was overcorrected and > the other left at plano. Now that's just silly. What leads you to believe the results would be any different? > There are people out there that purposely > induce more myopia by overcorrecting themselves. You can read this on > some message boards. I dont understand why they want worse eyes but > thats another topic entirely. They can stimulate pseudomyopia, but there's no evidence that their "real" myopia responds at all. > "Then we should stop using it? It works for me, several times a day, > confirmed by overrefraction." > > It doesnt apply for me nor many of my friends. Yes but you've admitted to pseudomyopia. It's easy to argue that you manifest more of it in glasses than contacts. > "Then the -600 is too much or the -475 is not enough." > > she sees her BCVA with both solutions. Her UCVA is worse than mine, > confirmed by removing our glasses and reading a large sign, she had to > move closer than me. I tried her glasses and they are sure strong. None of which gives me any assurance that her refraction is correct. > "If I had a patient with -600 contacts who overrefracted zero, and I > made > glasses with -750, I'd expect to have the glasses thrown back at me." > > try overrefracting his -7.5 glasses. I certainly have. After 25 years, I've done it about as many ways as it can be done. > This topic still confuses many people and is subjected to much debate. > There are some that will argue the conversons of vertex distance while > others will argue they are wrong. That's why we use math. The formula for effective lens power is not subject to opinion and it's verified in practice several thousand times a day. Your results are variable because your tonic accommodation is variable. As you get older, the variation will decrease and your experience will fall into line with everyone else's. > contacts while another -5 guy only needed -3.75 contacts. This is a > tricky subject where results vary slightly case by case basis. Results vary when your accommodation is overactive. When your accommodation is gone, your results will be more stable and predictable. > I found that adding plus to blur is more > reliable, particularly with younger people. Plus to blur? > "Pseudomyopia" and "liking overcorrection" are essentially the same thing. Namely what thing? Is there myopesthenia somewhere? > > The study would have been much better if one eye was overcorrected and > > the other left at plano. > Now that's just silly. What leads you to believe the results would be any > different? What leads him to believe that an eye can be plano? Plano is for a piece of glass. Well, that is what I have heard, anyway. > Yes but you've admitted to pseudomyopia. Can a patient's opinion be trusted? Does anybody know what is meant by pseudomyopia, anyway? Can any two people agree on its meaning? Patients are advised never to admit anything. > > This topic still confuses many people ... > That's why we use math. Good idea. Patients do not understand math, but they well never admit it. > As you get older, the variation will decrease and your experience will fall into > line with everyone else's. You won't be able to see sh.t! But maybe there will be chip implants. Maybe play computer games in your eyes when there is nothing on your visual horizon. > Results vary when your accommodation is overactive. When your accommodation > is gone, your results will be more stable and predictable. Something to look forward to! Never give up hope! -- Dicky http://www.chinamyopia.org/mainenglish.htm http://www.preventmyopia.org/ http://www.preventmyopia.org/htmlanimation.html I wish I knew about this when I was 12 and got my first -1 glasses! I probably could have slowed or halted myopia progression and not be the -5 I am now :( My brother is lucky that he refused to wear glasses so hes still a -1! My sister refused to wear glasses for some time but then ever since she went to contacts her eyes have been worsening! Theres nothing I can do to reverse my enlongated axil length of my eyeball but I can still resolve all my pseudomyopia. "After a few years of doing it, I found that adding plus to blur is more reliable, particularly with younger people. Of course I'm happy for anyone else to do it your way, because it leads to more mistakes and makes me look better. :) " why not do it both ways? Its another 5 minutes of his time that can save me a lifetime of incorrectly pescribed contacts. Ill get an overrefraction and also an underrefraction to double check the results for consisity. ""Pseudomyopia" and "liking overcorrection" are essentially the same thing. It's _while_ you're being tested that you "like overcorrection." Many folks do. Then most of them find the glasses hard to wear." so cycoplegic refractions should start being the standard for anyone under 40 to prevent overcorrecting them then when their pseydomyopia changes, their glasses wont be right anymore. Last time I got an exam I was measured at -5.5(left) and -5(right) but those glasses are too strong now, I feel dizzy wearing them and things are unreadable from near due to overcorrection. "They can stimulate pseudomyopia, but there's no evidence that their "real" myopia responds at all." how much pseudomyopia is really possible? I hear of people increasing their pescription by -10 diopters after many years. They started plano or mildly myopic and ended up with more than -10 diopters. "Yes but you've admitted to pseudomyopia. It's easy to argue that you manifest more of it in glasses than contacts." How does this work, how is this possible? If im seeing clearly with -4 contacts then I shouldnt be getting glasses much stronger than -4 to begin with! Whats with glasses that causes "overcorrection" or "pseudomyopia" and why is that every contact ive been sampled with was exactly 1.25 times stronger than glasses? -1 contacts= -1.25 glasses -2 contacts= -2.5 glasses and so on. I would think the vertex distance to be porportional. "None of which gives me any assurance that her refraction is correct." I just know her UCVA is worse than mine and her glasses are stronger than mine. Maybe she also has "pseudomyopia" like I do and is why she likes -6 glasses but sees fine with -4.75 contacts? "Your results are variable because your tonic accommodation is variable. As you get older, the variation will decrease and your experience will fall into line with everyone else's" so why not give people like me a cycoplegic refraction if their glasses and contact lense preference does not "match" accroding to your math formula. I know alot of other people who have a preference identical to mine. see examples below 1. she wears -3 contacts but her -3 glasses dont fully correct her 2. This guy wears -2 glasses and -1.75 contacts 3. another lady wears -1 contacts and -1.25 glasses 4. A guy online wears -6 contacts and -7.5 glasses 5. My female friends a -6 in glasses and -4.75 in contacts all of them need glasses 1.25 times stronger than their contacts. Could pseudomyopia be very common? >http://www.chinamyopia.org/mainenglish.htm > [quoted text clipped - 5 lines] >probably could have slowed or halted myopia progression and not be the >-5 I am now :( That's not what the research shows. >My brother is lucky that he refused to wear glasses so >hes still a -1! My sister refused to wear glasses for some time but >then ever since she went to contacts her eyes have been worsening! 1) n=2 - not science 2) post hoc, ergo propter hoc (correlation does not imply causation) - not science Don't be so sure that putting you in glasses at age 12 did *anything* to your eyes. Best available research shows it didn't. Also, the mere fact that Otis Brown thinks it *did* should, all by itself, convince you that it *did not*. >Theres nothing I can do to reverse my enlongated axil length of my >eyeball but I can still resolve all my pseudomyopia. Now *that's* correct. SignatureLive simply so that others may simply live Dear Acema, I think you are correct -- that if you had support for "prevention" before you started with the minus -- your vision could be clear now. Here is the scientfic proof for your interest. Subject: Pure Fact, Pure Science Re: What science tells us about the eye's dynamic behavior. "You see, Watson, but you do not perceive". Sherlock Holmes ** Here are the objective facts that prove that the natural eye is a dynamic device, and highly responsive to an applied lens. 1. Frank Schaeffel, Adrian Glasser and Howard C. Howland, "Accommodation, Refractive Error and Eye Growth in Chickens", VISION RES., Vol 28, No. 5 pp 639-657, 1988. Pergamon Press. RESULTS: All eyes (refractive state) treated with positive lenses became consistently more positive. Negative lenses produced more negative refraction (focal states) in all eyes. In a test of plus/minus lenses on left/right eyes, the eye with the plus lens moved in a positive direction. The eye with a minus lens moved in a minus direction. The control groups eyes did not change significantly in any direction. > I wish I knew about this when I was 12 and got my first -1 glasses! I > probably could have slowed or halted myopia progression and not be the > -5 I am now The problem is none of the research shows that it works consistently, except in pseudomyopia. If it worked, one of the 30 or 40 studies over the last 30 years would surely have turned up some positive results and repeated trials would confirm them. It just hasn't happened. > "After a few years of doing it, I found that adding plus to blur is > more reliable, particularly with younger people. > why not do it both ways? Its another 5 minutes of his time that can > save me a lifetime of incorrectly pescribed contacts. You must not have read me correctly. If one technique is more accurate and consistent, why confuse the issue? > Ill get an > overrefraction and also an underrefraction to double check the results > for consisity. If you use those terms, nobody will know what you're talking about. "Overrefraction" means a refraction "over" contact lenses. Ideally, the result should be zero. "Overcorrection" means putting -2.00 on an eye that actually only needs -1.25. That can be done with glasses or contacts. Either way, the far vision is pretty good and the near vision is unnecessarily strained. "Undercorrection" means putting -1.25 on an eye that actually needs -2.00. Glasses or contacts, the distance vision is blurry and near vision is great. > so cycoplegic refractions should start being the standard for anyone > under 40 to prevent overcorrecting them then when their pseydomyopia > changes, their glasses wont be right anymore. If you're going to be cyclopleged every day, then it makes sense. Otherwise, you'd probably find the glasses blurry at a distance. Why would you want blurry distance vision? > Last time I got an exam I > was measured at -5.5(left) and -5(right) but those glasses are too > strong now, I feel dizzy wearing them and things are unreadable from > near due to overcorrection. If you want good results next time, tell the doc that you're prone to pseudomyopia and let him deal with it. If you expect him or her to do it your way, you'll both mess up. If you get a refraction of -475 it should mean that -450 was blurry and -500 wasn't more legible. > how much pseudomyopia is really possible? I hear of people increasing > their pescription by -10 diopters after many years. They started plano > or mildly myopic and ended up with more than -10 diopters. Pseudomyopia is more common in the young, because it's easier for them to accommodate. On average, myopes get better all on their own between ages 30 and 50. > How does this work, how is this possible? If im seeing clearly with -4 > contacts then I shouldnt be getting glasses much stronger than -4 to > begin with! Normally that indicates that the two prescriptions were done at different times. In my office, people who need -400 contacts usually do just fine with glasses of -425. Glasses with -400 are slightly blurry, and glasses with -450 are no better than -425. > Whats with glasses that causes "overcorrection" or > "pseudomyopia" and why is that every contact ive been sampled with was > exactly 1.25 times stronger than glasses? -1 contacts= -1.25 glasses -2 > contacts= -2.5 glasses and so on. I would think the vertex distance to > be porportional. I don't know why your results have been so variable. I would guess it's instrument myopia, a tendency to show more myopia with an instrument up in your face. > "None of which gives me any assurance that her refraction is correct." > > I just know her UCVA is worse than mine and her glasses are stronger > than mine. Maybe she also has "pseudomyopia" like I do and is why she > likes -6 glasses but sees fine with -4.75 contacts? I can't guess why someone somewhere has such a difference. > so why not give people like me a cycoplegic refraction if their glasses > and contact lense preference does not "match" accroding to your math > formula. I usually do. > I know alot of other people who have a preference identical to > mine. see examples below> [quoted text clipped - 3 lines] > 4. A guy online wears -6 contacts and -7.5 glasses > 5. My female friends a -6 in glasses and -4.75 in contacts Again, I can't speak for "some guy somewhere." I only know what happens when I refract, and with those differences, most doctors would feel something is wrong. > all of them need glasses 1.25 times stronger than their contacts. Could > pseudomyopia be very common? Pseudomyopia is very common. In the form of "tonic accommodation," most young people have at least a half-diopter of it. Especially farsighted people: when a farsighted person with a +400 rx takes off their glasses, they must exert the same effort as someone with -400 D of pseudomyopia. Many of the young ones don't even notice it. -MT "The problem is none of the research shows that it works consistently, except in pseudomyopia." Then I could have prevented pseudomyopia and avoided the unnessesary strain on my eyes and even if I I couldnt prevent myopia, I could have slowed it down. Had I known, I would have used plus lenses for reading to ease the strain of close work and slow down myopia progression and avoid more pseudomyopia. ""Overrefraction" means a refraction "over" contact lenses. Ideally, the result should be zero." I would be able to accomodate a small amount of overcorrection. Youd either need to initially undercorrect me with contacts or cycoplegize me. Another option is just keep giving me plus lenses till I start to experience a myopic blur. If I can still see whatever my BCVA is with a +.75 lense than a +1 lense starts to make things a tiny bit blurry then the pescription I need should be weaker by .75 diopters. "Why would you want blurry distance vision? to help resolve pseudomyopia. If I want pseudomyopia to go away, I have to give a chance for my ciliary musles to relax so the lense can stop accomodating when it shouldnt. Next time I go to the optometrist, I am getting a pescription based on my cycoplegic refraction. I wonder if my pseudomyopia is the cause of my accomodative dysfunction. Since im in constant accomodation, I have little accomodation left. I can see fine from near without correction but the more correction I get, the more blurry things from near become. If it isnt pseudomyopia responsable for my poor accomodation, then I may just have early presbyopia ". If you get a refraction of -475 it should mean that -450 was blurry and -500 wasn't more legible." I did the is one or is two better test and just chose the best. However my manifast refraction is lower now than it was 8 months ago because some pseudomyopia has been resolved. I see blurry from near with my manifast refraction pescription. "Pseudomyopia is more common in the young, because it's easier for them to accommodate. On average, myopes get better all on their own between ages 30 and 50." this explains why alot of older people are farsighted. They may have been latant hyperopes or their lenses changed and they now are farsighted. I see tons of them in readers or bifocals "Normally that indicates that the two prescriptions were done at different times. In my office, people who need -400 contacts usually do just fine with glasses of -425. Glasses with -400 are slightly blurry, and glasses with -450 are no better than -425." I have some contact samples home with me and I made sure to try them at the same time. I have a photocopy of the snellen eyechart. I need -5 glasses for my BCVA but I can achieve the same with -4 contacts! I have a pair of -4.25 glasses too and my sample of -3.25 contacts are very nearly as good as those glasses. How do you know someone needs -4 contacts if he sees fine with -4.25 glasses? What if he can see fine with a lower contact pescription like is in my case and the case of my friends? "I don't know why your results have been so variable. I would guess it's instrument myopia, a tendency to show more myopia with an instrument up in your face." if were talking the autorefractor then yes that thing "overcorrected" me but a manual refraction is my objective results of "one or two is better" "Again, I can't speak for "some guy somewhere." I only know what happens when I refract, and with those differences, most doctors would feel something is wrong." How often do you get a refraction that doesnt add up? Such as someone needing -5 glasses but can see just fine with -4 contacts or someone seeing fine with -3 contacts but needs -3.75 glasses? Alot of my friends are like that. "most young people have at least a half-diopter of it." this explains why most people improve anywhere from -.5 diopters to -2 diopters with eye exercises. They are resolving their pseudomyopia. I am going to have to bug my parents to get me another eye exam asap and get a cycoplegic refraction > "The problem is none of the research shows that it works consistently, > except in pseudomyopia." [quoted text clipped - 4 lines] > to ease the strain of close work and slow down myopia progression and > avoid more pseudomyopia. Pseudomyopia will resolve over time. Having glasses (or contacts) too strong doesn't lead to more axial myopia. > I would be able to accomodate a small amount of overcorrection. Youd > either need to initially undercorrect me with contacts or cycoplegize > me. Another option is just keep giving me plus lenses till I start to > experience a myopic blur. That's how I determine endpoints. Every one of my (myopic) patients must tell me that one step less correction is blurry. > If I can still see whatever my BCVA is with a > +.75 lense than a +1 lense starts to make things a tiny bit blurry then > the pescription I need should be weaker by .75 diopters. That's exactly what I do. > "Why would you want blurry distance vision? > > to help resolve pseudomyopia. If I want pseudomyopia to go away, I have > to give a chance for my ciliary musles to relax so the lense can stop > accomodating when it shouldnt. Good reasoning. > I wonder if my pseudomyopia is the cause of my accomodative > dysfunction. Since im in constant accomodation, I have little > accomodation left. I can see fine from near without correction but the > more correction I get, the more blurry things from near become. If it > isnt pseudomyopia responsable for my poor accomodation, then I may just > have early presbyopia I think you have a very good idea of what's going on. > "Pseudomyopia is more common in the young, because it's easier for them > to [quoted text clipped - 5 lines] > been latant hyperopes or their lenses changed and they now are > farsighted. I see tons of them in readers or bifocals You're right. > good as those glasses. How do you know someone needs -4 contacts if he > sees fine with -4.25 glasses? Because a -425 spectacle lens has the same effect as a -400 contact lens, whether it's in front of an eye or a camera or a projector. > What if he can see fine with a lower > contact pescription like is in my case and the case of my friends? This happens every week or two. Usually it's right after we determined the spectacle refraction, so I quietly adjust the spec prescription downward, maybe by half the difference between observed and expected. >> "I don't know why your results have been so variable. I would >> guess it's instrument myopia, a tendency to show more myopia [quoted text clipped - 3 lines] > me but a manual refraction is my objective results of "one or two is > better" Unless your eye doctor was 70 years old, he probably had a phoropter against your face when the one-or-two test is done. > How often do you get a refraction that doesnt add up? Such as someone > needing -5 glasses but can see just fine with -4 contacts or someone > seeing fine with -3 contacts but needs -3.75 glasses? Alot of my > friends are like that. I see it once every week or two. > "most > young people have at least a half-diopter of it." [quoted text clipped - 3 lines] > am going to have to bug my parents to get me another eye exam asap and > get a cycoplegic refraction I'm usually not in a hurry to "fix" pseudomyopia, but I would work with anybody who was trying to resolve it. -MT Dear Acema, Subject: The offer of the plus -- for prevention. The problem is none of the research shows that it works consistently, except in pseudomyopia." [Comment: If you begin wearing an over-prescribed minus lens, the pseudo-myopia converts itself into "real" myopia. OSB] Then I could have prevented pseudomyopia and avoided the unnessesary strain on my eyes and even if I I couldnt prevent myopia, I could have slowed it down. [Comment: It think you could have stayed out of it completely, be "clearing" your pseudo-myopia when your "chart" went down to about 20/50. But rather intense commitment is required to "clear" your vision at that point. It is neither casual nor easy -- just a possibility. However it can not be "administered" under an "optometrists". The huge "explosions" against true-prevention on sci.med.vision should tell you that. OSB] Had I known, I would have used plus lenses for reading to ease the strain of close work and slow down myopia progression and avoid more pseudomyopia. Otis> That is my judgment also. But it seems that most people do not "like" the concept -- so there is no way you can help them. Otis> But there are optometrists who are now helping their own children, even as they know the public will reject the "correct" use of the plus for prevention, see: www.chinamyopia.org Otis> I always advocate that we work TOGETHER towards this better solution, and on this site I get these "Warinings" by some idiot posting here. Otis> If you wonder why you get no science nor common-sense support for true-prevention -- when you truly need it -- then that is the reason. Best, Otis > [Comment: If you begin wearing an over-prescribed minus lens, > the pseudo-myopia converts itself into "real" myopia. OSB] Faith is the evidence of things not seen. -MT Thanks for your reply, Mike. I would have thought vertex distance was porportional but I notice the higher the pescription, the greater the difference between glasses and contacts. Assuming contacts always sit directly on the eye(like it should) and glasses always sit 2cm away from the eye, why does the difference keep growing the more power you need? Every contact I have tried always provided a constant 1.25 ratio. -1 contacts = -1.25 glasses -2 contacts = -2.5 glasses -3 contacts = -3.75 glasses -4 contacts = -5 glasses The above is the constant ratio of contacts to glasses that has the effect on my eyes. With lower power contacts the difference isnt very much but I can notice very much difference once we get into the -2.5 and higher contacts. If im seeing fine with -4 contacts but things are a little blurry with my -4.25 glasses, should I just stick with those -4.25 since this is the real power I am supposed to need anyway! I know quite a few others who respond exactly the same as I do. If pseudomyopia is to blame, how does it "know" the difference between glasses and contacts? Otis Brown believes in myopia prevention. Of course its too late for me, but I have seen my own brother accidentally "prevent" his myopia from progressing, he just refused to wear glasses and only seems to for driving. Hes still myopic but its improved by half diopter in the last 3 years so that must have been pseudo. He does have a diopter of real myopia but its not bad enough to need glasses except to drive and the good thing is he can see fine from near without reading glasses. I also can as long as im not wearing glasses or itll become blurry from near. > and higher contacts. If im seeing fine with -4 contacts but things are > a little blurry with my -4.25 glasses, should I just stick with those > -4.25 since this is the real power I am supposed to need anyway! My opinion, yes. > I know > quite a few others who respond exactly the same as I do. If > pseudomyopia is to blame, how does it "know" the difference between > glasses and contacts? I can only speculate. What's different with contacts is there's nothing sitting on your face and there's no minification. > Otis Brown believes in myopia prevention. Of course its too late for > me, but I have seen my own brother accidentally "prevent" his myopia > from progressing, he just refused to wear glasses and only seems to for > driving. Yes, but Otis won't admit that on average, human myopes who don't wear glasses get just as nearsighted as those who do. A study with n=1 is trumped by studies with n=36 or n=300. -MT > Thanks for your reply, Mike. I would have thought vertex distance was > porportional but I notice the higher the pescription, the greater the > difference between glasses and contacts. Assuming contacts always sit > directly on the eye(like it should) and glasses always sit 2cm away > from the eye, why does the difference keep growing the more power you > need? Every contact I have tried always provided a constant 1.25 ratio. I don't know where these figures come from BUT using effectivity correction tables : A spectacle lens of -1.00DS at a vertex distance of 20mm from the will give effective power at the eye of -0.98D So if the contacts, not being RGP/hard have a power of -4.00D then at 20mm the power of the lens will be -4.37D (an extrapolated answer.) The reason for excluding RGP type lenses is that for fitting/calculaion puposes a +0.50D tear lens is assumed. Though in practice this will vary. [ In the power under discussion a -4.00D RGP lens will be based on -3.50D corneal refraction giving at 10mm a -3.62D spectacle lens and at 20mm -3.75D spectacle lens] Incidently the average vertex distance for a pair of spectacles is nearer 10mm than 20mm For a further expalnation I suggest you read 'The Optics of Contact Lenses' by A G Bennett, or 'Emsley and Swaine's Ophthalmic Lenses' revised by A G Bennett and R B Rabbetts > -1 contacts = -1.25 glasses > -2 contacts = -2.5 glasses > -3 contacts = -3.75 glasses > -4 contacts = -5 glasses |
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