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Medical Forum / General / Vision / March 2007Question about ciliary muscles, focus and myopia...
Hello, I'm 28 years old and have a certain degree of myopia. I never had it checked, but I have reasons to believe I need about a minus 2 to minus 2.5 diopter lens, in order to fully correct it. I definitely start to sense some loss in focus, when I'm ~3 feet from an object (like text on a screen), and of course it becomes worse the farther I get from the object. My question is this: if I start to sense a loss of focus starting from ~3 feet, does it mean that at this distance, my ciliary muscles are already relaxed to their most ?. The logical answer should be "yes", but I want to make sure, because it's weird to me that the adjustment that the eye makes when (for example) shifting from an object at 3000 feet, to an object at 3 feet, is just an adjustment in convergence, but not in ciliary contraction (i.e lens curvature). Thanks very much to anyone who can help. > I definitely start to sense some loss in focus, when I'm ~3 feet from > an object (like text on a screen), and of course it becomes worse the > farther I get from the object. This indicates 1 diopter, not 2 or 3. > My question is this: if I start to sense a loss of focus starting from > ~3 feet, does it mean that at this distance, my ciliary muscles are > already relaxed to their most ?. Pretty much, yes. > it's weird to me that the adjustment that the eye makes when (for > example) shifting from an object at 3000 feet, to an object at 3 feet, > is just an adjustment in convergence, but not in ciliary contraction > (i.e lens curvature). The difference in vergence between infinity and three feet isn't zero, but it isn't big either. Vergence and accommodation are intimately tied together - normally you can't do one without the other. But a tiny amount of vergence will only stimulate a tiny bit of accommodation, probably less than the half-diopter of leeway you get from depth-of-field. -MT Thank you very much for your answer, but there is something I don't understand: You agreed that at 3 feet, my ciliary muscles are already relaxed to their most (i.e no accomodation is done). But, you also said that "Vergence and accommodation are intimately tied together - normally you can't do one without the other". So, when I'm looking at a small letter from 3 feet, you want to tell me that my eyes are practically doing no convergence ? (because you agreed they are practically doing no accomodation - no cililary contraction - and you said both accomodation and vergence are tied together). > <Biology...@gmail.com> wrote > [quoted text clipped - 24 lines] > > -MT Why don't you stop w.nking around in NG's and get an eye test? You don't know what you have, so don't hypothesize and find out for real. You could have maculopathy, Retinitis pigmentosa, corneal dystrophy, astigmatism, posterior lenticonus, keratoconus, pellucid marginal degeneration or a plethora of other conditions. Herpes, AIDS and bipolar disorder also come to mind. Stop being a dickhead and get an eye test. dr grant p.s. stay away from my practice I was not asking for a diagnosis, so I'm not sure where all the anger came from... > Why don't you stop w.nking around in NG's and get an eye test? You > don't know what you have, so don't hypothesize and find out for real. [quoted text clipped - 8 lines] > > p.s. stay away from my practice > Thank you very much for your answer, but there is something I don't > understand: > > You agreed that at 3 feet, my ciliary muscles are already relaxed to > their most (i.e no accomodation is done). Well, your ciliary muscles contract a little just because you're alive. Many myopes measure a quarter or half-diopter less myopic after strong cycloplegia. > So, when I'm looking at a small letter from 3 feet, you want to tell > me that my eyes are practically doing no convergence ? (because you > agreed they are practically doing no accomodation - no cililary > contraction - and you said both accomodation and vergence are tied > together). Of course they have to converge, else you'd see double. With some degree of convergence comes some degree of accommodation. But it's a negligible amount of accommodation, less than the "tonic" amount described above, and less than the depth-of-field in normal conditions. What's the point? Are you having symptoms? What problem are you trying to solve? -MT Dear Friend, Rather than talking about your visual acuity, why not just check it? Just click here http://www.smbs.buffalo.edu/oph/ped/IVAC/IVAC.html Then click on "display" and read at 20 feet. Report back, and the friendly ODs here can discuss your visual acuity with you. You mention slight blurring at 3 feet, or 36 inches. If that is the point of "just blur" your refraction would be about -1.1 diopters (39.4/36). But the best check of visual acuity it to read your Snellen. Best, Otis On Feb 23, 2:39 pm, Biology...@gmail.com wrote: > Hello, > [quoted text clipped - 17 lines] > > Thanks very much to anyone who can help. > Dear Friend, Dear Friend, Please disregard Otis's postings. He is not in the medical profession and not in any position to give medical advice. Thanks! Allen > If that is the point of "just blur" your refraction > would be about -1.1 diopters (39.4/36). > > But the best check of visual acuity it to read your Snellen. Measuring the farpoint is more accurate than deriving diopters from Snellen acuity. If you had any training, you'd know that. -MT On Feb 23, 2:39 pm, Biology...@gmail.com wrote: > Hello, > [quoted text clipped - 17 lines] > > Thanks very much to anyone who can help. Your ciliary muscles would not necessarily be fully relaxed. some cycloplegia would take care of that. Just to clarify, I'm not trying to get diagnosed here. This is just a theoretical debate about myopia. This is what I understand up to now: Fact: At 3 feet from an object, I am seeing fuzzy. Explanation: The reason is that the rays of light coming from the object located 3 feet in front of me, get focused in front of my retina, instead exactly at my retina. Now, the paradox is that at 3 feet, I'm led to believe in this thread, that my ciliary muscles are *contracted*, and hence make the lens more curved than it can be. If my ciliary muscles would have totally relaxed at 3 feet, I could have seen much better, but people in this thread claim it can't relax, because it is linked to the convergence state of the eyes: For each convergence state of the eyes, there is an appropriate accomodation state. This is a link that can not be broken or changed, or at least that's how I understand Mike Tyner's claim. I think that Mike Tyner claim, as I explained it above, does not fit with the observations in reality. The observation I'm talking about is the following: let's say a person with a normal vision is looking at an object located 2 feet in front of him, at this point, he has a certain convergence and accomodation state in his eyes. Now, what will happen if this guy, in this exact same situation, will now wear glasses with "+" or "-" 1 diopter lens ?. In order to still see the object from 2 feet clearly, he will have to change the accomodation of his eyes (reduce it if it's a plus diopter lens, or increase it if it's a "-" diopter lens), but he will have to do this, *without* changing the convergence state of his eyes. Of course we know people *can* make this change successfully, and so after a brief moment of accustoming, that person will see the object focused again, now with the glasses. >From this observation, it is easy to see that accomodation and convergence, can be changed *independently* of each other, their states can be decoupled from one another. This leads me to conclude, that in my situation, at 3 feet, I can only see fuzzy, after my eyes exhausted the accommodation factor, and reduced it to the minimum possible in order to try and alleviate the lack of focus that is caused by the image getting focused in front of my retina. This means that at 3 feet from an object, my ciliary muscles should be totally relaxed, even though the ciliary muscles of a person with 20:20 vision, will not be relaxed at this situation. Do you agree with my conclusion, and if not, why ?. On Feb 23, 11:49 pm, "michael toulch" <michaeltou...@hotmail.com> wrote: > On Feb 23, 2:39 pm, Biology...@gmail.com wrote: > [quoted text clipped - 24 lines] > > - Show quoted text - Mike Tyner, I only saw your response after I posted my last one. I now see you weren't saying what I thought you were saying. The reason I started this whole debate is because I would like to get glasses, but I don't want to use it in any situation that will cause my ciliary muscles to contract. Using minus diopter glasses in close proximity situations, will cause the ciliary muscles to contract, in case the image get focused after the retina. I just wanted to make sure, that both at 3 feet, and at 30 feet, my ciliary muscles are preactically at the same relaxation level, meaning I can use the glasses in both situations, without fearing that in any of them the ciliary muscles will contract. My fear is that excessive ciliary contraction has led me (and so many of my university friends who don't have myopian parents) to get myopia. I also going to get a minus lens that will not fully solve my problem, because I don't want to risk an overshoot situation that will focus the image after my retina, causing ciliary contraction. On Feb 24, 1:42 am, Biology...@gmail.com wrote: > Just to clarify, I'm not trying to get diagnosed here. This is just a > theoretical debate about myopia. [quoted text clipped - 77 lines] > > - Show quoted text - Of course even though both at 3 feet and at 30 feet, my ciliary muscles might be more or less relaxed to the same degree, still, correcting the problem to 30 feet, will give me a minus diopter that will focus the image behind the retina when looking at 3 feet objects. So maybe the only solution is to go with more than one glasses. On Feb 24, 2:04 am, Biology...@gmail.com wrote: > Mike Tyner, > I only saw your response after I posted my last one. I now see you [quoted text clipped - 103 lines] > > - Show quoted text - Btw, what is the formula to deriving diopters needed for correction, from measuring the farpoint ?. On Feb 24, 2:16 am, Biology...@gmail.com wrote: > Of course even though both at 3 feet and at 30 feet, my ciliary > muscles might be more or less relaxed to the same degree, still, [quoted text clipped - 114 lines] > > - Show quoted text - Nevermind, I've found it: D = -1/d(far), where d(far) is in meters. On Feb 24, 2:51 am, Biology...@gmail.com wrote: > Btw, what is the formula to deriving diopters needed for correction, > from measuring the farpoint ?. [quoted text clipped - 121 lines] > > - Show quoted text - > Nevermind, I've found it: > D = -1/d(far), where d(far) is in meters. Dear Friend, I can tell that you are a very smart person. That formula was also listed in our recent post titled "Vision Improves in Days" on Feb 20, 2007. Please take a look at our website where you can find some more info on myopia, the side effect of wearing the minus lens, etc. Best regards, Myopia Cure Promoter http://www.geocities.com/myopiacure "Vision Improvement is EASY if done PROPERLY" Thanks. In your website you show a graph where the usage of a minus lens glasses increaces myopia. Well, I can only see this happening if by using the minus lens, you are pushing the image behind the retina, and then have to contract the ciliary muscles to compensate. As I said, I will not be using the minus lens in any situation that could push the image behind the retina. I'm going to buy one pair of glasses for lectures and driving, which will put the object from "infinity" (20 feet and more), just a little bit before the retina. Apart from this, I'm going to buy another pair of minus glasses for TV. I sit 8 feet from the TV at home, so I will not use the driving/ lectures glasses for this purpose, because it will push the object's image behind the retina. I have a question though, assuming I need a -1.5D lens to correct for infinity, is there a simpe formula that could tell me what minus lens will I need in order to correct for 8 feet ?. On Feb 24, 3:31 am, myopiac...@yahoo.com wrote: > Biology...@gmail.com wrote: > > Nevermind, I've found it: [quoted text clipped - 13 lines] > Myopia Cure Promoterhttp://www.geocities.com/myopiacure > "Vision Improvement is EASY if done PROPERLY" > Thanks. In your website you show a graph where the usage of a minus > lens glasses increaces myopia. Don't ask where the graph came from. Don't consult Medline, don't ask any professors, don't look up myopia in a graduate textbook. Instead, let's ask some guy with a web site. If I showed you a graph demonstrating that wearing shoes causes the feet to grow, would you believe that too? -MT Dear Biology, Subject: The fundamental eye's response to an applied -3 diopter lens. Rather than guessing about the effect of a -3 diotper lens on the eye -- why not just run the experiment and find out. See: http://www.geocities.com/otisbrown17268/FundEye.html What happens, is that: 1. The accommodation system will change by -3 diopters, and per the applied -3 diopter lens, and then, 2. After four months, the eye will change its refractive STATE by about -2 diopters. Just pure biological science. The natural eye performs as designed. Some people don't believe this, but these are the facts, not speculation. Best, Otis On Feb 23, 9:07 pm, Biology...@gmail.com wrote: > Thanks. In your website you show a graph where the usage of a minus > lens glasses increaces myopia. Well, I can only see this happening if [quoted text clipped - 35 lines] > > - Show quoted text - If these statistical profiles are not clear, then check out the biology and behavior of the fundamental eye on: http://vision.berkeley.edu/wildsoet/myopiaprimer.html Look at the way the natural eye changes its refractive STATE (length if you wish) when the -3 diopter lens is applied to it -- and it changes by about -2 diopters. Neat graphics! Excellent perspective. Enjoy, Otis On Feb 23, 11:48 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > Dear Biology, > [quoted text clipped - 66 lines] > > - Show quoted text - > If these statistical profiles are not clear, then check out > the biology and behavior of the fundamental eye on: Dear Biology, Please disregared Otis's postings. He is not in the medical profession and not in any position to give medical advice. Thanks! Allen Dear Biology, Subject: Clarification. Allen> Please disregard Otis's postings. Allen> He i snot in the medical profession and not in any position to give medical advice. Yes, Bilogy, I am not "snot" in the medical profession. But Allen thinks he his snot in the profession. There are too many people here who are "paternalistic" -- that is THEY want to do YOUR thinking for you. I think you are intelligent enough to realize that truth. Look at the facts themselves, and try to subtract-out the rather intense bias that is involved in scientific preception of the behavior of the NATURAL EYE, under direct test. Otis > "otisbr...@pa.net" <otisbr...@pa.net> wrote innews:1172292905.284673.93880@t69g2000cwt.googlegroups.com: > > If these statistical profiles are not clear, then check out > > the biology and behavior of the fundamental eye on: [quoted text clipped - 7 lines] > > Allen Several of you have criticised my observation that excessive accomodation, can raise the chances to develop myopia. Living in Israel (where I'm located), you have to bury your head deep deep in the sand, in order not to see the connection between accomodation and myopia. In Israel we have several towns where there is a high concentraion of religious jewish people. Our religious people, starting at youth, spend most of their day reading from books (many many hours per day), while the non-religious jews, spend just a fraction of their day reading from books. I invite each and every one of you to pay a visit to a high school class of religous students, and to compare it to a high school class of non-religous students. In the religous high-school, I will say that over 90% wear eyeglasses, while at the non-religious high school, the precentage of people wearing glasses (and I mean minus diopter glasses, of course) is profoundly smaller. It's a day and night difference. The counter-argument that some of you gave, is that if I was correct, then a "+2 hyperopic" person, would have had higher chances to develop myopia. I have three things to say about it: 1. Are you sure you are correct ?. Has anyone ever checked if a population of +2 hyperopic people (that are like this for at least several years), aren't more myopic in average, than a random population of the same size ?. 2. Even if the above was checked and found to be incorrect, it still does not mean that excessive accomodation doesn't help to develop myopia. It could be that the trigger to the myopian state, only happen when the ciliary muscles are contracted passed a certain state. When people read a book, they are contracting their ciliary muscles much more than a +2 hyperopic person who gaze at the distance. What about +3 or +4 hyperopic people, are they not more prone to myopia than a random group of people ?, was this ever checked ?. 3. Another explanation could be that hyperopic people *do* have longer eyebals, i.e their excessive accomodation *did* led to an increase in eyebal length, but not enough to solve the hyperopic state. Was there ever an experiment made to check the geometric proportions of hyperopics eyeball, to see if it is less round than the average ?. On Feb 24, 5:22 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > Dear Biology, > [quoted text clipped - 38 lines] > > - Show quoted text - Regarding options #1 and #2 that I raised in my earlier post, I was making them under the assumption that a person could be both hyperopic and myopic. The person could be hyperopic because his ciliary muscles can not contract well enough, or his lens lost its ability to curve enough. This same person could be also myopic, if for example his eyeballs are longer than they should be, so objects from infinity will focus before the retina. But by saying this, I suddenly see that a hyperopic person (hypeopic from the reasons I mentioned above), will not have to accomodate at all for objects in the distance, so I would not expect him to be more prone to develop myopia. Now I think I understand why one of you talked about a hyperopic *kid* - assuming that the reason this kid is hyperopic, is because a too narrow eyeball (and not the reasons I mentioned above, which are probably more relevant to older hyperopics). Based on this new understanding, your counter-argument actually said: hyperopic children where the cause is narrow eyeballs, shouldn't have existed if accomodation would have caused myopia (by lengthening the eyeball). I could still see why this doesn't necessarily has to be so: 1. Like I said in argument #2, it could be that the trigger for mypia (caused by accomodation), only happen once the accomodation is much stronger than +2D. 2. It could be that the eyeball of these children do gain more lengh due to excessive accomodation, but this lenghening isn't enough to cure the hyperopic state completely. Maybe a certain type of my former argument comes into place, and stop the eyeball-lengthening once the accomodation-pressure drops below a certain threshold, and this is why hyperopic children (where the cause is a narrow eyeball) still exist. On Feb 24, 6:09 pm, Biology...@gmail.com wrote: > Several of you have criticised my observation that excessive > accomodation, can raise the chances to develop myopia. [quoted text clipped - 85 lines] > > - Show quoted text - And I could think about another possibility: 3. It could be that many potentially hyperopic children (where the cause is a narrow eyeball), never get to the eye-doctor in the first place, because accomodation-depended lengthening of their eyeball, has cured them from the small hyperopia (or at least kept it from getting worse to a state they need a doctor). Under this assumption, the hyperopic children we do see today (where the cause is a narrow eyeball) are the small percentage in the population, in which accommodation does not lead to lengthening of the eyeball. On Feb 24, 6:41 pm, Biology...@gmail.com wrote: > Regarding options #1 and #2 that I raised in my earlier post, I was > making them under the assumption that a person could be both hyperopic [quoted text clipped - 124 lines] > > - Show quoted text - My intelligent friend, Subject: The refractive STATES of the natural eye. As the Wildsoet animation showed, the NATURAL eye controls it refractive STATE to CHANGES in it average value of accommodation. The refractive STATES of the natural eye in the WILD, run between zero to +3 diopters -- and are completely NORMAL. See the "older" refractive profile of the natural Eskimo eye. http://www.geocities.com/otisbrown17268/DynamicEye.html When you place this NATURAL eye in a long-term near situation, i.e., 12 years in school, the natural eye simply follows the AVERAGE VALUE of accommodation, and the refractive profile of the NATURAL EYE becomes an average of -2 diopters with a spread from zero to -5 diopters. It is just a matter of basic engineering and science. Best, Otis On Feb 24, 11:56 am, Biology...@gmail.com wrote: > And I could think about another possibility: > [quoted text clipped - 139 lines] > > - Show quoted text - "If accommodation caused myopia, NONE of the hyperopes would get worse. They'd all get better. They don't. As a rule, they get worse." But maybe the hyperope kids who get worse, are those in which accommodation does not trigger myopia (they are a small percentage of the population, but still they exist, and they are the hyperope kids you see at the eye clinic). To every rule there is an exception... On Feb 24, 7:13 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > My intelligent friend, > [quoted text clipped - 173 lines] > > - Show quoted text - My intelligent friend, Subject: Using clear words to describe the behavior of the fundamental eye. Re: False idealizations of the past -- and there consequence. A "theory" was developed about 150 years (call it the Donders-Helmholtz concept). It simplified the discussion about the eye. The theory was this. Only a refractive STATE of exactly zero could be called normal. ALL OTHER STATES WERE DEFECTS OR ERRORS. The word coined for a refractive STATE of exactly zero was "emmetropia". All other eyes were "ametropia", or "error" or "fault". This was a sweeping and WRONG conclusion. Because of this wrong-headed concept, refractive STATES that are absolutly normal are classed as "hyperopia". Thus if you have 20/20, and a positive refractive STATE, which is normal, you are told your eyes have ERRORS. By this logic, a negative refractive STATE of -1 diopter was called an "error". Here, there MIGHT be some logic to it -- but is it rather superficial. Based on the performance of the natural eye, (Wildsoet, blue-tint animation), it is clear that the natural eye is dynamic when tested in SCIENCE. But when medical people see it, out comes the WRONG vocabulary -- which is bound to confuse everyone. You stated that you wished a theoretical discussion about the concept of the natural eye's behavior -- and proof? The the issue must start with taxonomy and concept. Oh, and remember, there are second-opinion optometrists who support both the science and method of prevention. See: www.chinamyopia.org for practical application of the science of the eye's proven behavior. Best, Otis On Feb 24, 1:19 pm, Biology...@gmail.com wrote: > "If accommodation caused myopia, NONE of the hyperopes would get > worse. [quoted text clipped - 186 lines] > > - Show quoted text - Getting into a pissing contest with otis is like having an intelligent conversation with a cinder block. Dear Second-opinion (preventive) friends, Subject: Well intended advice. Re: The response of a majority-opinion OD. [A good friend sent me this suggesting I work WITH a majority-opinion optometrist on prevention at the threshold. Indeed, attempting to get a M.O. OD to think logically about the fundamental eye's proven behavior, is like trying to reason with a brick. "Biology" remarks about Hassadic kids being 90 percent negative refractive STATE is indeed the truth of the natural eye's behavior. That is an intelligent observation. Perhaps we should learn TOGETHER, that our eyes have engineering-scientific limitations, and that we can protect our long-term distant vision with intelligent use of the plus. OSB] +++++++++++++ Friend> We have lost precious time that we could have been using to get the word out about plus prevention. Friend> This is time you could have spent talking to optometrists or optometry students or parents or children who could make a difference. Otis> And here is the majority-opinion optometrist who I must "talk to" about assisting parents and children with plus-prevention, at the thresold (20/50, -3/4 diopters) before it gets beyond the point of effective prevention with the plus. =============== >From Dr. Catman Grant Speaking seriously, and as a professional, there are a few points I wish to make. 1) In my consulting room, as you correctly stated, I am God. 2) I earned that right through study, hard work and developing a reputation for quality work, excellent results and caring for my patients and their welfare. 3) You have not earned that right. You are a pathetic little pissant that insults the very fibre of prevention of myopia. You do not deal with 20 patients a day wanting to see clearly, you do not have to ensure that a kid can see the board in class, as well as read and function outside the classroom. 4) You have no concept of the issues, I and every other OD must face on a daily basis for the best welfare of each and every one of our patients. You prefer to pontificate about evil minus and second opinion crap, whose supporters are less credible than yourself. 5) You keep talking about second opinion doctors, but never name any other than Steven Leung. Why is this? I do know several OD's in Hong Kong and Singapore and Steven Leung is held in the esteem that I hold you and Nancy. He has no basis to his method, he just uses the fear of parents to sell his glasses for his own profit. His website is a fraud and most of the links don't work. There is no scientific validation, just fear-mongering. All in all, you are a pathetic, miserable sycophant that has nothing to provide other than fear. No answers, no proof, nothing. Crawl back under your rock and fester away. dr grant (CatMan), a majority-opinion OD. ================ Talking to a person who declares himself a "God" -- is impossible. You would have to be naive to think that there could be ANY RATIONAL CONVERSATION with such a "God". When I SUGGEST that you my be forced to do it yourself -- then this man's attitude against plus-prevention is indeed the reason. Look to your own resources for prevention -- because you will get only hostility from Catman Grant. It is better that I talk to the person himself about Catman Grant's incredible arrogant and IGNORANT attitude, and the effect his over-prescribed minus is going to have on the un-suspecting public. I EXPECT more that this from a so-called "professional". The Second-opinion PROFESSIONAL will be found at: www.chinamyopia.org But learn this well -- the parent and child must take this seriously at the thresold. Just one man's opinion. Otis > Getting into a pissing contest with otis is like having an intelligent > conversation with a cinder block. On Feb 24, 7:35 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > Dear Second-opinion (preventive) friends, > [quoted text clipped - 12 lines] > that we can protect our long-term distant vision with intelligent > use of the plus. OSB] But you won't learn. And you won't discuss. And you won't explain directly contradictory evidence. And you won't seek to understand failures in your method. And you don't seek to reconcile differences between animal data and human data. And you generalize from small sample sizes to large populations. And you don't answer logical, direct questions. So ... others HAVE tried ... REPEATEDLY ... to work "together" with you. But you won't. You simply want them to agree with you, practice what YOU preach, and ignore available data. How's that supposed to work?? [crap snipped] On Feb 24, 7:35 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > Talking to a person who declares himself a "God" -- is > impossible. Those of us who have tried, for years, to reason with you certainly understand that. > You would have to be naive to think that there could be ANY > RATIONAL CONVERSATION with such a "God". ibid > When I SUGGEST that you my be forced to do it yourself -- > then this man's attitude against plus-prevention is indeed the > reason. Uh ... what? Everybody here rails against YOU, Otis ... and for thousands of perfectly valid reasons. It's YOU. Just YOU. > Look to your own resources for prevention -- because you will > get only hostility from Catman Grant. And ... like that nice pedophile in the Cadillac ... you'll get politeness from Otis .... but ... look out for the rest. > It is better that I talk to the person himself about > Catman Grant's incredible arrogant and IGNORANT attitude, > and the effect his over-prescribed minus is going > to have on the un-suspecting public. What does "over-prescribed" mean. Can you please provide some credible basis for that assertion? No? Okay. > I EXPECT more that this from a so-called "professional". The > Second-opinion PROFESSIONAL will be found at: > > www.chinamyopia.org Fly to Hong Kong and see Steve. He'll sell you a book. Of course, he has no credible evidence of arresting myopia progression either, but .... > But learn this well -- the parent and child must take this > seriously at the thresold. Doom and Gloom The War Cry of Elevator Boy > Just one man's opinion. Literally .... and he can't defend it, either. Only propound it ... time after time after time after time.... On Feb 24, 1:19 pm, Biology...@gmail.com wrote: > "If accommodation caused myopia, NONE of the hyperopes would get > worse. [quoted text clipped - 4 lines] > the population, but still they exist, and they are the hyperope kids > you see at the eye clinic). To every rule there is an exception... But the myopes are the small group: Only 20% to 28% of Israelis are myopic, are you saying that there is something different about them, something that makes them become myopic if they accommodate, something ..... genetic perhaps? Investigative Ophthalmology and Visual Science. 2005;46:2760-2765.) The Changing Prevalence of Myopia in Young Adults: A 13-Year Series of Population-Based Prevalence Surveys Yosefa Bar Dayan,1,2 Avi Levin,1,2 Yair Morad,3 Itamar Grotto,1 Rachel Ben-David,1 Avishai Goldberg,4 Erez Onn,1 Isaac Avni,3 Yehezkel Levi,1 and Oren Gil Benyamini3 PURPOSE. To determine the changing prevalence of myopia during the years 1990 through 2002 among the 16- to 22-year age group and identify possible risk factors. METHODS. A retrospective study, based on 13 repeated prevalence surveys conducted over a 13-year period. The study subjects were all Israeli nationals belonging to the 16- to 22-year age group from the years 1990 to 2002. Refraction was determined by using subjective visual acuity followed by noncycloplegic autorefraction and subjective validation based on the autorefraction results. Mild myopia was defined as a refractive error of -0.50 to -3.00 D in at least one eye, moderate myopia as -3.25 to -6.00 D, and high myopia as more than - 6.00 D. RESULTS. There were 919,929 subjects (382,139 [42%] females and 537,790 [58%] males) included in the study. The overall prevalence of myopia increased from 20.3% in 1990 to 28.3% in 2002. The prevalence of high, moderate, and mild myopia significantly increased in males from 1.7%, 5.7%, and 11.6% in 1990 to 2.05%, 7.2%, and 16.3% in 2002, respectively (P < 0.001). In females, the prevalence of myopia increased from 1.9%, 6.6%, and 13.5% in 1990 to 2.4%, 9.2%, and 20.7% in 2002, respectively (P < 0.001). A correlation between myopia and the number of years of education was observed. Non-Israeli origin was found to be a significant risk factor for myopia. Dr. Judy, you said: >It is not a small percentage. About 75% of adult caucasians are >hyperopic So. using your thinking, in the majority of people >accommodation does not cause eyeball growth. But what you are forgetting, is that most of these 75%, are not myopic due to inherently narrow eyeball, rather they developed it over the years, due to a loss in the ability of the lens to get round enough, or loss in some of the ability of the ciliary muscles to contract. These types of hyperopes, will not contract their ciliary muscles to see distant objects well (they have no problem with distant vision), so there is no reason to believe that the myopic pathway to enlarge the eyeball will be activated in those hyperopes. Judy, you also said later: >But the myopes are the small group: Only 20% to 28% of Israelis are >myopic, are you saying that there is something different about them, >something that makes them become myopic if they accommodate, >something ..... genetic perhaps? Again, you are saying that the myopes are the small group, and quote a 20% to 28% percent. This percentage is indeed smaller than 75% (that you quoted for hyperopes), but as I said above, most of the people in this 75%, are not the type of hyperopes who can switch on the myopia mechanism to elongate the eyeball. Also, the article you quoted said two things: 1. During the years checked (1990 - 2002) myopia increased. 2. "A correlation between myopia and the number of years of education was observed. Non-Israeli origin was found to be a significant risk factor for myopia". Both of these findings, are supportive of the fact that myopia is caused by focusing on near objects for long period. For your knowledge, 1990 was about the year where personal computers started entering our country for home usage. > On Feb 24, 1:19 pm, Biology...@gmail.com wrote: > [quoted text clipped - 43 lines] > the number of years of education was observed. Non-Israeli origin was > found to be a significant risk factor for myopia. On Feb 25, 2:40 pm, Biology...@gmail.com wrote: > Dr. Judy, you said: > [quoted text clipped - 6 lines] > years, due to a loss in the ability of the lens to get round enough, > or loss in some of the ability of the ciliary muscles to contract. Again, you are misunderstanding refactive error. The loss of flexibility in the lens that occurs after age 40, is not called hyperopia it is called presbyopia. Presbyopia happens to hyperopes, myopes and emmetropes. Hyperopia, to repeat, is the image of distance objects focused behind the retina when the ciliary muscle is relaxed. Most adults, age 20 and up, are hyperopic to some small degree, if only 1-2 diopters. They cannot see distance clearly if the eye does not accommodate, they accommodate all the time both while viewing at distance and at near. See the link below for more information about presbyopia, you can also search the site for information about hyperopia. http://www.nlm.nih.gov/medlineplus/ency/article/001026.htm > These types of hyperopes, will not contract their ciliary muscles to > see distant objects well (they have no problem with distant vision), Again, you are incorrect. Only emmetropes can see well at distance with a relaxed ciliary muscle. > Also, the article you quoted said two things: > [quoted text clipped - 8 lines] > knowledge, 1990 was about the year where personal computers started > entering our country for home usage. You have made the classic error of assuming correlation means causation. High education is associated with myopia as is higher IQ. This, in no way, is evidence that focusing on near objects causes myopia. Dr Judy Neil Brooks, you said: >Then it's settled. >If you're a simple myope, then don't wear your minus lenses for near >work. >Now you've just agreed with a conclusion widely recommended by >optometrists for decades ... even if only for simplicity's sake. I had no intention to state the obvious. Indeed I said: >...then I can fully understand Otis's argument that a minus lens is not a good >idea, if by using it, the person is going to have to accomodate his eyes much >more frequently. But what I meant is that in the optometrist's clinic, myopes are getting a lens with a minus diopter strength, that will allow them to have the image from an object at "infinity" (i.e 6 meters and more), to focus on their retina, and not before. Now, using this minus lens glasses for objects which are at a distance of less than "infinity" (less than 6 meters), will put the image *behind* the retina (assuming no accommodation of the eye). In the real world, many myopes use their minus glasses most of the time (as long as they're no reading, even though I saw some who even don't remove it when reading), they do a lot of close work with their minus lens glasses, whether it's writing in a notebook at the lecture, or eating, or many other activities. All this puts excessive, unnecessary pressure on the ciliary muscles, which can make myopia accelerate. > On Feb 24, 1:19 pm, Biology...@gmail.com wrote: > [quoted text clipped - 43 lines] > the number of years of education was observed. Non-Israeli origin was > found to be a significant risk factor for myopia. On Feb 25, 11:51 am, Biology...@gmail.com wrote: > Neil Brooks, you said: > [quoted text clipped - 25 lines] > unnecessary pressure on the ciliary muscles, which can make myopia > accelerate. It /could/, but ... as I have stated here many times before ... I'm a high hyperope. For years, my accommodative amplitudes were fully locked up in a severe ciliary spasm (from a combination of undercorrection and intensive reading demands). After a lengthy course (months) of daily cycloplegic eyedrops, the spasm "broke." When the spasm broke, several things happened: - much better vision at every distance - return of relatively age-appropriate accommodative amplitudes - relief of pain, nausea, and fatigue (asthenopia) - reduction of esotropia (accommodative component) - ZERO change to my cycloplegic refraction After /years/ of intense ciliary accommodative stress, I had NOT become more myopic (less hyperopic) at all. Why? I should have. I'd have been happy if I did. But I didn't. Is it genetic pre-disposition (or something else), or is it multi- factorial? If genetics is the primary mover, and ... SINCE accommodation and convergence are inextricably linked ... THEN if you're NOT genetically predisposed to myopia, an intervention such as plus lenses WITHOUT being evaluated and monitored for binocular function issues could lead ... and HAS LED to binocular function problems (eg, double vision)--arguably a much worse problem than low, simple myopia that may or may not ever progress. Also, it would be critical -- primarily because of the above -- to understand the timeline during which an emmetropization process takes place, and when it no longer can or will. If all of this works ad infinitum, then ... why is Otis a -6d myope? Hmmm. Oversimplifying ... uh ... biology ... is rarely accurate. We're complex organisms. Well ... most of us. Sadly, not Otis. On Feb 25, 2:51 pm, Biology...@gmail.com wrote: snip > In the real world, many myopes use their minus glasses most of the > time (as long as they're no reading, even though I saw some who even [quoted text clipped - 3 lines] > unnecessary pressure on the ciliary muscles, which can make myopia > accelerate. A myope wearing corrective minus lenses while reading accommodates no more than an emmetrope wearing no lenses while reading and considerably less than an hyperope reading without glasses. The only case that suffers excessive accommodation is the uncorrected hyperope. The majority of caucasian adults have mild hyperopia, do not use glasses to read and thus are over accommodating. Yet they do not become myopic, nor does their hyperopia reduce. How do you explain this? Dr Judy On Feb 24, 11:56 am, Biology...@gmail.com wrote: > And I could think about another possibility: > [quoted text clipped - 6 lines] > eyeball) are the small percentage in the population, in which > accommodation does not lead to lengthening of the eyeball. It is not a small percentage. About 75% of adult caucasians are hyperopic So. using your thinking, in the majority of people accommodation does not cause eyeball growth. So why, in the minority who do become myopic, does accommodation causes eyeball growth? Could it be genetic? Dr Judy On Feb 24, 11:41 am, Biology...@gmail.com wrote: > Regarding options #1 and #2 that I raised in my earlier post, I was > making them under the assumption that a person could be both hyperopic [quoted text clipped - 3 lines] > eyeballs are longer than they should be, so objects from infinity will > focus before the retina. You have a misunderstanding of refractive error. Loss of ciliary muscle tone or loss of lens flexibility is presbyopia and only affects near vision. Hyperopia is defined as an eye in which the retinal image of a distant object is focused behind the retinal plane when accommodation is at rest, ie when the ciliary muscle is relaxed. Myopia is when that same retinal image of a distant object in an eye with a relaxed ciliary muscle focusing in front of the retinal plane. In order for a hyperope to see clearly at distance, he must accommodate by contracting the ciliary muscle by an amount equal to the hyperopia. So a 2D hyperope accomodated 2D when viewing distance objects. A 2D myope accommodates not at all while viewing distance since accommodation will only move the retinal image further in front of the retina. While reading, say at 50cm for a 2D demand, the hyperope will need to accommodate 4D (2 to clear the distance, then another 2 to clear from distance to near), while the 2D myope will not need to accommodate at all. So from this you can see that hyperopes are accommodating all the time, for all distancea, and at a greater amount than myopes. My question to you remains: if accommodation causes the eye to grow and myopia, how can it be that hyperopes exist? About 75% of adult caucasians are hyperopic-- why doesn't that hyperopia go away? > But by saying this, I suddenly see that a hyperopic person (hypeopic > from the reasons I mentioned above), will not have to accomodate at > all for objects in the distance, so I would not expect him to be more > prone to develop myopia. You are incorrect, hyperopes must accommodate to clear the distance. > 1. Like I said in argument #2, it could be that the trigger for mypia > (caused by accomodation), only happen once the accomodation is much > stronger than +2D. But all hyperopes accommodate more for every viewing distance than do myopes. Yet they remain hyperopic. > 2. It could be that the eyeball of these children do gain more lengh > due to excessive accomodation, but this lenghening isn't enough to > cure the hyperopic state completely. Maybe a certain type of my former > argument comes into place, and stop the eyeball-lengthening once the > accomodation-pressure drops below a certain threshold, and this is why > hyperopic children (where the cause is a narrow eyeball) still exist. This line of thinking still doesn't explain how accommodation causes myopia. If the excess accommodation that hyperopes experience cannot cause enough eye growth to eliminate hyperopia, how can it be the cause of the excessive growth seen in myopes? Most children are hyperopic at birth, and through childhood up to puberty. If accommodation is the cause, why do only 25% of them become myopic? Some hyperopes get less hyperopic. But after age 5 or 6, the percentage is not more than the percentage of random individuals who get myopia. If accommodation caused myopia, NONE of the hyperopes would get worse. They'd all get better. They don't. As a rule, they get worse. -MT Dear Biology, I made no "medical" statement at all. I just refered you to the scientific facts, and suggested that you be intelligent enough to think for yourself. Best, Otis > "otisbr...@pa.net" <otisbr...@pa.net> wrote innews:1172292905.284673.93880@t69g2000cwt.googlegroups.com: > [quoted text clipped - 9 lines] > > Allen > I just refered you to the scientific facts, > and suggested that you be intelligent enough > to think for yourself. But be careful not to test human myopes. -MT Please think about the following for a moment, and tell me where I'm wrong: Assuming you have a device (some kind of a prism with plus lens) that makes the convergence and accommodation for the eyes, so they won't have to do it by themselves. As a consequence from wearing this device, when reading from 1.5 feet, the eyes will be in a physically *identical* state as when reading from a huge screen, located 30 feet from the eyes. Now, by making a large group of people (that spend each day 10 hours reading from 1.5 feet) wear this device while doing close work, there are too possibilities that will happen after several years: 1. The correlation between focussing on close objects and myopia will disappear for the group wearing this device (actually they weren't really focussing on close objects). If this will happen, it means either convergence or accommodation or both are the culprit. It really can't be something else in this case, because the device hasn't done *anything else* but to take the need from the eyes to do convergence and accommodation. But there could be another consequence: 2. The correlation between focussing on close objects and myopia will *not* disappear for the group wearing this device. In this case, I think we won't be able to avoid the conclusion that this correlation has nothing to do with the fact that the objects are close per se. Instead of this, we will have to accept that the reason that looking at close objects for long periods of time, increases the chances to develop myopia, has to do with something in the visual image on the retina that we get while looking at letters/numbers or something else common to the visual image from close objects. An immidiate consequence of what I said, is that this will have to happen also if you read from very far using huge screens, which for me is very hard to believe, because of what I wrote before about the body's characteristic of adapting to things we do often. > "otisbr...@pa.net" <otisbr...@pa.net> wrote innews:1172292905.284673.93880@t69g2000cwt.googlegroups.com: > [quoted text clipped - 9 lines] > > Allen >Please think about the following for a moment, and tell me where I'm >wrong: [quoted text clipped - 6 lines] >from the eyes. > Google search on "myopter", for your device, which might also be called a contraption. I'm not sure what % of the conv. and accom. functions are "taken up" by the myopter, but I imagine it's much more than you could practically get with ordinary glasses, because the prisms involved with spectacles by themselves would be so strong that there would be a terrific amount of color dispersion (rainbows). >Now, by making a large group of people (that spend each day 10 hours >reading from 1.5 feet) wear this device while doing close work, there >are too possibilities that will happen after several years: > There is a 3rd possibility that is far more likely than either of yours. Everyone will drop out of the study because of the weight, appearance and inconvenience of using such a device. Would you be caught dead wearing one in public? w.stacy, o.d. After checking out the "myopter" I tend to agree. I had no clue the device I portrayed will look so horrible in reality. I prefer going with minus glasses rather than with this monstrous "myopter". Still, for the sake of the argument, I would be thrilled to see the results of an experiment done with such myopter device (expecially one which can take full duties of accommodationa and convergence from 1.5 feet). It would have shed so much light on the issue for me. > Biology...@gmail.com wrote: > >Please think about the following for a moment, and tell me where I'm [quoted text clipped - 24 lines] > > w.stacy, o.d. >After checking out the "myopter" I tend to agree. I had no clue the >device I portrayed will look so horrible in reality. I prefer going [quoted text clipped - 5 lines] >feet). It would have shed so much light on the issue for me. > Maybe try it out on residents of GITMO? Naw, even those tough guys wouldn't wear it. Maybe you (or someone) should order the patent and redesign it using today's technology and put a little fashion in it. Could be a real money maker if it works, is comfy on the nose, and looks sexy... > Google search on "myopter", for your device, which might also be called > a contraption. I'm not sure what % of the conv. and accom. functions > are "taken up" by the myopter, but I imagine it's much more than you > could practically get with ordinary glasses, because the prisms involved > with spectacles by themselves would be so strong that there would be a > terrific amount of color dispersion (rainbows). Don Rehm, one of Otis' good buddies and fellow ranter (check out his website, myopiafree.com) invented the Myopter about 35 years ago -- I heard about in Optometry school circa 1975. At the time he had not tested it in a clinical trial. Despite his incredible rants against NIH and vision scientists for ignoring his device, after 35 years he still has no clinical trial data. Maybe he tried and it didn't work, maybe he didn't try. Anyway, the onus is on him to provide the evidence. Dr Judy Dr. Judy said: > Don Rehm, one of Otis' good buddies and fellow ranter (check out his > website, myopiafree.com) invented the Myopter about 35 years ago -- I [quoted text clipped - 4 lines] > maybe he didn't try. Anyway, the onus is on him to provide the > evidence. I agree that the onus is on him to provide evidence that the myopter reduces the chance to develop myopia. Sadly I don't think he'll ever do that. Saying that, I think those who hold the notion that the chances for developing myopia do not increase by excessive convergence and/or accomodation, have an obligation to provide evidence that the myopter doesn't work. The name "myopter", or the identity of the person who created it, or the identity of his "buddies", are irrelevant. What is relevant is that you need to prove that a device that totally free the eyes from the need to do convergene and accommodation, doesn't reduce the chances for myopia. No experiment like this was ever done, and the results of such test are unknown. On Mar 2, 11:07 am, Biology...@gmail.com wrote: > Dr. Judy said: > [quoted text clipped - 10 lines] > accomodation, have an obligation to provide evidence that the myopter > doesn't work. You are quite wrong in that. If someone invents a new health gizmo, the onus is on that person to provide evidence that it is safe and effective. There is no obligation on anyone else's part. Similarly, if someone has the hypothesis that convergence and accommodation cause myopia, it is up to that person to do research to support the idea. Dr Judy Dr. Judy, I think most (if not all) will agree that reading text on large screens from 30 feet, shouldn't make the chances for developing myopia become higher. But reading text on large screens from 30 feet, is exactly what happens when you read with a device that takes the need from the eyes to accommodate and converge. This means that most people, whether they know it or not, support the notion that excessive convergence and/or accommodation raise the chances to develop myopia. This is why in order to accept any other theory (to explain the correlation between close work and myopia), we first have to reject the general belief. DrG said: > The factor you may wish to consider is something called the > accommodative stimulus-response curve. At infinity, there exists in > most subjects tonic accommodation of about 0.50 diopters. At one > meter, the average accommodative response equals the stimulus. > Therefore, from the standpoint of accommodation, there is really no > point at all to what you are trying to accomplish. What do you mean by "the average accommodative response equals the stimilus" ?. > On Mar 2, 11:07 am, Biology...@gmail.com wrote: > [quoted text clipped - 22 lines] > > Dr Judy On Mar 2, 1:24 pm, Biology...@gmail.com wrote: > What do you mean by "the average accommodative response equals the > stimilus" ?. You do understand the difference between a stimulus and a response, and if the stimulus to accommodation is zero (infinity), the response is approximately 0.50 diopters. For a stimulus of greater than 1.00 diopter (1 meter), the response is less than 1 diopter, i.e. there is a lag of accommodation. DrG DrG said: > You do understand the difference between a stimulus and a response, > and if the stimulus to accommodation is zero (infinity), the response > is approximately 0.50 diopters. For a stimulus of greater than 1.00 > diopter (1 meter), the response is less than 1 diopter, i.e. there is > a lag of accommodation. I can understand the first part of your paragraph, where you said that for most people, with no stimulus for accommodation, the accommodation response is approximately 0.5 diopters. This goes hand in hand with what Dr. Judy said, that 75% of caucasians are hyperopes (i.e with zero accommodation response, object at infinity will focus behind the retina). I have trouble understanding the second part of what you said. If we assume that light should always stay focussed on the retina, then for a person who has 0.5D accommodation for a stimulus of 0D (in order for an object at infinity to focus on the retina, and not after it), I will expect an accommodation of 1.5D, for a stimulus of 1D, otherwise, if the accommodation is less than 1.5D for a stimulus of 1D, I don't understand how the light from the stimulus will be kept focussed on the retina, and not behind it. On Mar 2, 2:37 pm, Biology...@gmail.com wrote: > I have trouble understanding the second part of what you said. If we > assume that light should always stay focussed on the retina, then for [quoted text clipped - 4 lines] > understand how the light from the stimulus will be kept focussed on > the retina, and not behind it. Maybe your premises need re-examining. I measure the accommodation of patients at nearpoint all the time. Thus far, I haven't had a single patient whose image plane wasn't behind the retina after being corrected for the farpoint. DrG DrG said: > I measure the accommodation of patients at nearpoint all the time. > Thus far, I haven't had a single patient whose image plane wasn't > behind the retina after being corrected for the farpoint. Let me get this straight: a myope comes to an optometrist, he doesn't see well objects at infinity, because light from them focus before the retina. The optometrist fit him with a minus lens glasses that will cause the object from infinity to focus behind the retina, and the person does no accommodation to fight it. Two things I don't understand: 1. Why does the optometrist fit him a minus lens that will put the image from an object at infinity, behind the retina ?. When the optometrist uses a minus lens that cause an object at infinity to exactly reach the retina, why doesn't the patiant say "I see good" so the optometrist could stop decreasing the number further ?. 2. How can the image plane from the object at infinity stay behind the retina ?, how come the person does not accommodate to focus the light exactly at the retina ?, focussing the light behind the retina give a more detailed image than focussing it exactly at the retina ???. I'm totally lost here. On Mar 2, 4:25 pm, Biology...@gmail.com wrote: > DrG said: > [quoted text clipped - 15 lines] > exactly reach the retina, why doesn't the patiant say "I see good" so > the optometrist could stop decreasing the number further ?. This may or may not happen during refraction for distance. Often, the patient prefers to be slightly overcorrected and does not say "I see good" until that point. > 2. How can the image plane from the object at infinity stay behind the > retina ?, how come the person does not accommodate to focus the light > exactly at the retina ?, focussing the light behind the retina give a > more detailed image than focussing it exactly at the retina ???. I'm > totally lost here. Dr L was referring to the NEAR point, not the farpoint. Most people, at near, have the image slightly behind the retina. We don't know why, it is just the measured fact. Dear Biology, A simplified sketch of the accommodation system's response to its environment can be found at: http://www.geocities.com/otisbrown17268/AccoGraph.html In fact the normal eye has a continuous record of its average visual environment -- from the accommodation system. The normal eye controls its refractive STATE by reference to to this system. This is of course the second-opinion of the natural eye's behavior. This of course explains why these Jewish kids (with long-term near enviroment -- average) see their refractive STATE move from normal positive, to negative. Why make a basic scientific process complicated? I believe Occam's Razor applies here. Best, Otis On Mar 2, 4:25 pm, Biology...@gmail.com wrote: > DrG said: > [quoted text clipped - 21 lines] > more detailed image than focussing it exactly at the retina ???. I'm > totally lost here. > I believe Occam's Razor applies here. Occam's razor requires that your explanation account for _all_ the facts. You haven't accounted for the fact that inheritance is more important than environment. -MT > inheritance is more important than environment. > > -MT Hahahahahahahahahahahaha.................................................. On Mar 2, 7:10 pm, myopiac...@yahoo.com wrote: Did you hear the one about the kid who went from 20/120 to 20/40 in 8 days? > Hahahahahahahahahahahaha.................................................. Yes. That was my reaction as well. DrG On Mar 2, 3:37 pm, Biology...@gmail.com wrote: > DrG said: > [quoted text clipped - 10 lines] > zero accommodation response, object at infinity will focus behind the > retina). No it does not. The stimulas and response are measured against the corrected, not uncorrected refraction. Most people, corrected hyperopes and myopes both, accommodate a little bit at far. > I have trouble understanding the second part of what you said. If we > assume that light should always stay focussed on the retina, then for [quoted text clipped - 4 lines] > understand how the light from the stimulus will be kept focussed on > the retina, and not behind it. Yes, Mother Nature is strange. Please understand that these are not speculative values, they are actual measured values --- this is what the eye actually does as opposed to what you think it should do. People do not notice the blur because the pupil of the limits increases depth of focus. Dr Judy On Mar 2, 2:24 pm, Biology...@gmail.com wrote: > Dr. Judy, > I think most (if not all) will agree that reading text on large > screens from 30 feet, shouldn't make the chances for developing myopia > become higher. That is not true. As I pointed out to you earlier, some vision scientists have speculated that the lack of detail in text may serve the way that form deprivation does to stimulate myopia. Others have found that accommodation is less precise during cognitive tasks with the imprecise accommodation resulting in retinal blur which is know to cause myopia. They speculate that the actual task of reading, not the vergence and accommodation demands, may cause myopia. If that is true, then reading at 30 ft may also increase risk of myopia. But reading text on large screens from 30 feet, is > exactly what happens when you read with a device that takes the need > from the eyes to accommodate and converge. This means that most [quoted text clipped - 3 lines] > correlation between close work and myopia), we first have to reject > the general belief. Please do as I suggesed earlier and try a PubMed search using "Accommodation AND myopia" as the search term. As I pointed out, you will over 500 citations. Taken as a body of work, they strongly support the idea that accommodation is NOT the factor in near work that increases risk of myopia. Dr Judy Dr. Judy said: > That is not true. As I pointed out to you earlier, some vision > scientists have speculated that the lack of detail in text may serve [quoted text clipped - 4 lines] > vergence and accommodation demands, may cause myopia. If that is true, > then reading at 30 ft may also increase risk of myopia. Wow, now that is one bold, radical theory you have there. Reading from huge screens located at 30feet raises the chance for myopia, just wow!. Dr. Judy also said: > Please do as I suggesed earlier and try a PubMed search using > "Accommodation AND myopia" as the search term. As I pointed out, you > will over 500 citations. Taken as a body of work, they strongly > support the idea that accommodation is NOT the factor in near work > that increases risk of myopia. It could be that accommodation alone doesn't. It could be that accommodation AND convergence both should be eliminated. Of course no study ever tried to eliminate it both and see what happens. Instead, radical theories came up as an alternative, like the one whose consequence is that reading text from 30 feet will raise chances for myopia, i.e inability to read from 30 feet (throwing our body's known feature of adapting well to frequently encountered situations, out the window). Question for Otis Brown, Otis, how do you know that excessive convergence doesn't play an important role in developing myopia ?. You are preaching for the usage of plus lens in order for non-mypoes to stay non-myopes, but from many experiments that were done, it seems that stopping accommodation alone is not enough. Why aren't you preaching for the usage of the myopter, instead of just plus lens ?. After 100 posts in this thread, It is obvious than *no- one* here can present any evidence that will contradict the notion that fully freeing the eyes from the need to accommodate and converge, will lower chances to develop myopia. On Mar 3, 4:35 am, Biology...@gmail.com wrote: > Dr. Judy said: > [quoted text clipped - 27 lines] > feature of adapting well to frequently encountered situations, out the > window). Dear Biology, Subject: About preventing the ENTRY into a negative refractive STATE. I personally AGREE that prevention is tough. It will depend on a person's insights about the natural eye's proven behavior (in terms of refractive STATE). Whatever is said here, you simply can never "prescribe" it. It must be a "learning" process for the pilot (or highly motivated) person who chooses to make the strong personal commitment to clearing their distant vision -- UNDER THEIR OWN CONTROL. This is indeed the second opinion. The real issue is whether a person has the motivation to do it. And that does reamain an open question. To further respond: Question for Otis Brown, Otis, how do you know that excessive convergence doesn't play an important role in developing myopia ?. Otis> I prefer to say that the natural eye will simply change its refractive STATE when you place a -3 diopter lens on it. (It will change by -2 diopters in six months -- if you run this experiment under your control. In this case, no "convergence" was involved AT ALL. Thus, the natural eye uses the accommodation SIGNAL, to control its refractive STATE. This is a natural an normal process -- and must be understood that way. Or as the second-opinion if you wish. You are preaching for the usage of plus lens in order for non-mypoes to stay non-myopes, Otis> That is correct. But, I do SUGGEST that a person who starts dipping into a negative refractive STATE, consider altering his AVERAGE value of accommodation (as per the environment/accommodation graph), and by keeping his environment at zero diopters (with the plus) SLOWLY watch his Snellen clear from 20/60 to 20/40 or better. There is good science behind this concept, but it is also requires strong commitment by the person himself to make this process work correctly. but from many experiments that were done, it seems that stopping accommodation alone is not enough. Otis> That is because you pay attention to ONLY the majority-opinion ODs posting here. I would suggest that you pay more attention to the second-opinion expressed by Steve Leung at: www.chinamyopia.org Why aren't you preaching for the usage of the myopter, instead of just plus lens ?. Otis> Because of the refractive STATE of the eye responds to a CHANGE in its average value of accommodation. After 100 posts in this thread, It is obvious than *no- one* here can present any evidence that will contradict the notion that fully freeing the eyes from the need to accommodate and converge, will lower chances to develop myopia. Otis> With all due respect to you -- that is again the MAJORITY OPINION. The second-opinion study by Oakley-Young showed that the proper use of a STRONG PLUS, resulted in the test group NOT GOING DOWN, while the strong minus when down at -1/2 diopter per year, or -2 diopters in four years. Otis> The extereme bias of the majority-opinion is to deny, deny, deny. Otis> So you will have to make your own judgment here. Otis> But you are correct. There has NEVER been a plus-prevention study, run under SCIENTIFIC control -- YET. Otis> But perhaps as some time in the future we will get the opportunity to do so. Best, Otis On Mar 2, 9:57 pm, Biology...@gmail.com wrote: > Question for Otis Brown, > [quoted text clipped - 46 lines] > > - Show quoted text - On Mar 2, 7:17 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: [drivel snipped] > Otis> The extereme bias of the majority-opinion is to > deny, deny, deny. and yours is to lie, lie, lie. Did you just bring up Oakley-Young again?? Wow! > Otis> But you are correct. There has NEVER been > a plus-prevention study, run under SCIENTIFIC control -- YET. So get off your dead-a.s and get something going. It is obvious than *no- > one* here can present any evidence that will contradict the notion > that fully freeing the eyes from the need to accommodate and converge, > will lower chances to develop myopia. That's only because no-one here can get anyone to wear a myopter for more than 10 minutes. I repeat, get otis on it... On Mar 2, 9:35 pm, Biology...@gmail.com wrote: > Dr. Judy said: > [quoted text clipped - 14 lines] > > > Please do as I suggesed earlier and try a PubMed search using Subject: Verification of Judy's theory -- that the greater the distance, the more myopia will be induced. Dr. Judy said: Judy> That is not true. As I pointed out to you earlier, some vision > scientists have speculated that the lack of detail in text may serve > the way that form deprivation does to stimulate myopia. Others have [quoted text clipped - 3 lines] > vergence and accommodation demands, may cause myopia. If that is true, > then reading at 30 ft may also increase risk of myopia. Otis> OK, by that logic, then Eskimos reading the distance for polor bears, would run the risk of becoming seriously myopic, if they do a lot of reading beyond 30 feet. Otis> If Judy's theory is correct, then a large percentage of "hunting" Eskimos should be seriously myopic. I wonder how we can check her theory? Best, Otis > > "Accommodation AND myopia" as the search term. As I pointed out, you > > will over 500 citations. Taken as a body of work, they strongly [quoted text clipped - 9 lines] > feature of adapting well to frequently encountered situations, out the > window). On Mar 2, 7:00 pm, "otisbr...@pa.net" <otisbr...@pa.net> wrote: > On Mar 2, 9:35 pm, Biology...@gmail.com wrote: > [quoted text clipped - 39 lines] > "hunting" Eskimos should be seriously myopic. I wonder > how we can check her theory? Lying again, or just unable to read/understand what Judy =actually= said? Also (to "biology"): what about the Shotwell tests that DID use prism? IF the argument was that the prism was inadequate, then the question remains: should there not have been some directional information that resulted from the study? In other words, shouldn't relief--if not total prevention--of convergence diminished the rate of progression, or is it simply all or nothing..... It's darned significant that Rehm's never established =anything= in proper trials. No NIH conspiracy should have stopped HIM from getting something going. Also ... regardless ... AC/A and CA/C ratios--while there are normal ranges--variable from person to person. An evaluation would need to be made as to each person's AC/A AND CA/C (and vergence amplitudes, I'd think) in order to prescribe correct prism and plus, and/or establish cohort groups for controlled testing. Further, aren't there spasm of near reflex (SNR) patients whose refractive histories are well documented?? If somebody locked in both accommodative AND convergence spasm does not progress myopic at a greater rate than the norm, then ... it still sounds like it's elsewhere or multifactorial. > IF the argument was that the prism was inadequate, then the question > remains: should there not have been some directional information that > resulted from the study? In other words, shouldn't relief--if not > total prevention--of convergence diminished the rate of progression, > or is it simply all or nothing..... You might think that, but the problem I see is that the meager amounts of prism used in those reading glasses (I think they didn't even try to use pr |
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