A Compendium on Myopia Rehabililation

[Tom]

The Incremental Retinal Defocus Theory and its Merit

This shouldn’t be too relevant for most of you, but if you are interested, make sure you make it to the end.of this post. I thought I knew what IRDT is until I went through the papers by their authors - Chances are that one can't guess what IRDT is by its name.

Intro

Since Hung and Ciuffreda published their initial paper on Incremental Retinal Defocus Theory (IRDT), they have been trying to convince their colleagues about the predictive power of their theory. Namely, that IRDT is consistent with the recent myopia findings on the effects of undercorrection and light.

To begin, what exactly is this Incremental Retinal Defocus Theory (IRDT)? It’s an unifying theory on myopia development, maintaining that the decrease of retinal defocus, in a time increment, reduces the release rate of retinal neuromodulators, which in turn reduces the proteoglycan synthesis rate, rendering scleral tissues more vulnerable, which leads to an increase of the axial growth rate.

In a similar but opposite manner, IRDT also maintains that the increase of retinal defocus, in a time increment, will send a cascade of chemical signals which would ultimately retard the rate of axial growth.

Hung and Ciuffreda emphasizes that it’s the change of retinal-image defocus area, rather than the magnitude of defocus itself, that triggers the different behaviours of retinal neuromodulators (e.g., dopamine), and the ensuing effects on axial length.

Without further ado, Let’s look at what Hung and Ciuffreda have to say on different optical treatments on myopia.

The alleged effect of full-correction

With full correction, looking at optical infinity and 25cm do not result in substantial difference in retinal defocus. At optical infinity, although an individual might experience slight accommodation lead, the images at this distance are clear overall. Similarly, while at 25cm the same individual might experience a very slight accommodation lag, the presence of accommodation ensures that the retinal defocus at 25cm ultimately remains minimal.

That is, assuming that the person’s accommodation amplitude is at least 4D, then the person’s accommodation system, which enables adaptation to various visual stimuli, ensures that changes in retinal defocus from far to near is minimal. As a result, there is little change in the rate of axial growth.

Problems

All seems good, except that people wearing full prescription tends to see their diopter increasing year after year (until it stabilizes). Are they progressing at a genetically-determined default rate? No. It’s generally false that full prescription stabilizes myopia. In fact, anecdotal reports invariably suggest that most myopes who switch to an +2 undercorrection (for far and near) experience a slight initial reduction in myopia.

In fact, my experience with myopia shows that full prescription does exactly the opposite of stagnating myopia. My myopia only stopped when I stopped using minus lens for close work, while simutaneously abstaining from focusing within 50cm. In brief, evidence suggests that the appeal to the so-called genetically-programmed progression rate is precisely an appeal to the “unquestioned wisdom from the past.”

The alleged effect of 0.75D undercorrection

Assuming that a person’s default distance is at optically infinity (i.e., -0.75D of accommodation stimulus), with the usual accommodation lead at far distance, the individual, with the accommodation “disabled” at far, now experiences a relatively significant retinal defocus at optical infinity (i.e, >= 6 meters).

However, during a close work session, the individual shifts from far to, say, 25cm, at which point the individual would experience a significant reduction of retinal defocus (after the adjustment made by the accommodation system). Consequently, an increase in axial growth rate would ensue, as a result of the cumulated effect of regular far-to-near activities.

Problems

I understand that these researchers were trying to find an approach that would explain the O’Leary et al. study, but I just have to say that the reasoning they cooked up is too much of a stretch (and this is not to even take into account the criticisms of that O’Leary study, which some believe either contains serious methodological flaws, or reveals no statistical significance between the full prescription group and the undercorrected group, after a correction on the data)

Dr. Alex Frauenfeld’s approach to myopia rehabilitation, which typically consists of giving a 1D undercorrection for far, and a 2D undercorrection for near, would probably make no optical sense according to IRDT. Firstly, the +1 undercorrection for far would “disable” the accommodation system, creating a significant amount of retinal defocus at far. Secondly, when a Frauenfeld patient focuses near slightly beyond their far point, there would be practically no retinal defocus.

What this means that the regular shifting from far to near represents a significant decrease of retinal defocus, and the magnitude of this decrease is even greater than that resulted from a typical 0.75D undercorrection. Consequently, one would expect a Frauenfeld patient to become even more myopic. In reality though, just the opposite is true. Frauenfeld patients generally fare very well with their myopia - Just the opposite of what Hung and Ciuffreda's reasoning would have predicted.

The alleged effect of strong plus lens

Wearing a strong plus in effect disables the accommodation system. As a result, a subject can no longer focus far and near equally well. Focusing far with plus lens then produces a significant increase of retinal defocus, which retards the axial growth rate over time.

Problems

Read between the lines and you might see a double standard emerging . There is an implicit assumption that the research animals don’t engage in far-to-near activities, and that’s the reason why there is an overall increase of retinal defocus. There are actually animal studies in which the focusing distance is controlled, so that animals only look at a particular distance most of the day.

Under those experimental settings, the increase of retinal defocus only happens in the initial days of the experiments. However, despite the lack of change in retinal defocus in the later days of the experiments, the myopia-inhibiting effect of plus lens still make itself present. IRDT would have predicted than little refractive change would occur in the later days of such an experiment.

Other predictions

Since children can accommodation fairly well, a small overcorrection would lead to little change in retinal defocus (after accommodation), hence the effect of overcorrection wouldn’t be significant. Similarly, since multifocals allows one to see both far and near equally well, IRDT predicts little change of myopia progression from the use of, say, bifocal.

Problems

Overcorrection in animals and humans invariably worsen myopia (dubbed by the mainstream as the normal genetically-programmed myopia progression rate). Previous studies on multifocals, especially the bifocals, do display some degree of myopia-inhibiting effect. These effects were brushed off as being insignificant.

Alledged ideal prescription

Hung and Ciuffreda suggests a full prescription for far, and a weak undercorrection (+0.5 or +0.75 add) for near tasks, as their computer simulation suggests that doing so would minimize any change in retinal defocus, and hence result in little myopia progression.

Problems

With these prescriptions, the patients would still experience chronic close strain. The full prescription ensures that ciliary never relaxes, and the tiny amount of undercorrection in the prescription for near almost guarantee that reading will be done with a fair amount of close strain.

Final words

The Incremental Retinal Defocus Theory is not a theory about minimal myopic defocus. Rather, it’s a theory about the change of retinal defocus, in an increment of time. In fact, IRDT would predict that constant edge-of-blur will produce no change in retinal defocus over time, thus no change in myopia progression.

IRDT strikes me as being out of touch with the reality of myopes. For the sake of completeness though, here is the link to one of Hung and Ciuffreda’s paper.

[Tom]

A Theory of the Development of Near-Stress-Induced Myopia - Mechanical Component

Many people (e.g., Bates method’s advocates, behavioral optometrists) came to suspect the connection between nearwork and reduced visual acuity. Here’s a theory of myopia based on the idea of near stress. I hope it helps in addressing some gaps in our current understanding about myopia.

Near Stress

The ocular system is intricately fine-tuned and highly adaptive to our visual environment. For example. the accommodation system, essentially composed of pupil, ciliary and the crystalline lens, constantly adjusts to the visual stimuli, based on their contrast, brightness, color, proximity, size, etc.

When focusing on a close object (i.e., within 1 meter) or confined in a near environment, the eye receives proximal cues from our surrounding. This would innervates the parasympathetic nervous system, which then activates the contraction of ciliary muscle. This process, called proximal accommodation, represents a coarse mechanism by which the eye adjusts to the visual stimuli. The degree of proximal accommodation depends on the perceived proximity of visual stimulus, and not necessarily on the degree of accommodative stimulus.

This means that regardless the prescription being used, engaging in near work within, say, 50cm, invariably triggers proximal accommodation, whose magnitude increases as we lean closer to the focusing object. Some remarks from Ip et al.:

Longer time spent on reading for pleasure and reports of close reading distance (< 30 cm) were associated with a more myopic refraction after adjustment for age, sex, ethnicity, and school type (P(trend) = 0.02 and P = 0.0003, respectively). Time spent in individual near-work activities, however, correlated poorly with SER (all r < or = 0.2) and was not significant in multivariate analyses for myopia (SER < or = -0.50 D), with adjustment for age, sex, ethnicity, parental myopia, school type, and outdoor activity.
[...]
Although myopia was not significantly associated with time spent in near work after adjustment for other factors, there were significant independent associations with close reading distance and continuous reading. These associations may indicate that the intensity rather than the total duration of near work is an important factor.

In addition to the coarse mechanism of proximal accommodation, a finer mechanism of accommodation also exists, which operates mainly based on the defocus of the visual stimulus (i.e., magnitude and direction of the defocus). This is called blur-driven accommodation, or simply accommodation for most people.

Emmetropization (i.e., the regulation of axial length during our growth) is essentially a byproduct of accommodation. However, blur-driven accommodation could be exploited to disrupt normal emmetropization and induce myopia. To illustrate, when a full minus prescription is used for reading at 50cm, the eye is exposed to 2D of accommodative stimuli. As a result, blur-driven accommodation kicks in. The ciliary tenses up, and the crystalline lens thickens in order to reduce the blur. This blur-driven accommodation increases as you negativize the prescription lens power and lean closer to focusing objects.

In addition to these two accommodative mechanisms, another one related to vergence, called convergence accommodation (i.e., accommodation that results solely from converging the eye axes) can also contribute to near stress as we move the eye axes nasalward (i.e., towards our nose). Just as focusing close increases convergence accommodation, the general use of traditional minus spectacle, whose prismatic effect increases esophoria and makes images appear smaller, also puts more convergence demand on our eyes.

Prolonged proximal, blur-driven and convergence accommodation put tremendous demand on the focusing muscle (i.e., ciliary) and the crystalline lens. This leads to accommodative stress, which is described anatomically by Dr. Kaisu Viikari as follows:

The accommodation spasm strains and swells the accommodation muscle (m.ciliaris, whose processus ciliares are responsible for secreting the aqueous humor). Also the lens of the eye thickens, producing stronger refraction. *On top of not working in an ideal fashion, these swollen anatomical structures take up space* and narrow the angle: the circulation and outflow of the aqueous humor are decreased, and the intra ocular pressure increases.

Just as convergence and accommodation can "increase" each other, convergence itself poses a threat in its own right. As a person leans very close towards an object, achieving better visual acuity requires the medial recti and oblique muscles to contract (by shortening themselves). This isotonic contraction would then move the eyeballs inwards so that image fusing becomes possible.

However, if the convergence is sustained, then the prolonged isotonic extraocular contractions would increase pressure in the vitreous chamber. This is the phenomenon of convergence stress.

Together, the joint phenomenon of accommodative and convergence stress is referred to as near stress, with close strain simply referring to their respective symptoms (e.g., pressure in the back of the eye, distance blurring).

The Effects of Prolonged Near Stress

In general, accommodative stress induces ciliary tension, making the crystalline lens rounder. Since the crystalline lens naturally tends towards a rounder shape (in order to release its internal pressure), eliminating accommodation after an episode of near stress will not undo the thickening of crystalline lens immediately.

This means that there is a time lag between the end of an accommodative-stress episode, and the full recovery of the ciliary and the crystalline lens (and the entire eye for that matter) to their original resting state. This phenomenon is coined accommodation hysteresis (also known as accommodative adaptation), with temporary near and distance blurring being its chief symptom.

Similarly, there is time lag between the end of a convergence-stress episode, and the full recovery of the medial recti and the oblique muscles (and the entire eye for that matter) to their original resting state. This phenomenon is coined vergence hysteresis, with temporary posterior ocular pressure and temporary pressure around the nose being its chief symptoms.

Depending on the intensity of near stress, hysteresis (accommodative or convergence alike) could last from minutes to hours. For those with more flexible ciliary, crystalline lens, extraoculars, and stiffer connective tissues (i.e., retina, choroid and sclera), hysteresis is almost not a concern. Consequently, these are the people who experience little myopia. On the end of the spectrum, some folks might exhibit innervation deficiency of sympathetic nervous system (which regulates ciliary relaxation) and cranial nerve III, IV and VI (e.g., those exhibiting a natural tendency to tighten the extraoculars) or they might just have less flexible ciliary/zonular fibers, extraoculars and weaker connective tissues. For them, hysteresis needs to be taken more seriously.

• Walker et al. - "ocular shape had become more prolate [i.e. stretched]. This shape remained unchanged after 1 hour of sustained accommodation and then returned to baseline dimensions after 2 h of accommodation ... Ocular shape returned to baseline dimensions after 45 min of accommodative relaxation."
  
  
• Carney et al. - "A tendency for the cornea to flatten less rapidly in the periphery with increasing myopia was shown."
  
  
• Sergienko et al. - " The hypermetropic and emmetropic eyes possess stiff sclera. Their AL remained practically unchanged during the elevation in IOP induced by the application of 30 g of external pressure. The absolute majority of myopic eyes revealed biomechanical weakness of the scleral shell. A higher degree of myopia was associated with increased AL elongation."
  
  
• Vasudevan & Ciuffreda - After 2h of near work at 35-40cm, emmetropes experience less transient myopia than both early-onset myopes and late-onset myopes. Early-onset myopes experience longer hysteresis than both late-onset myopes and emmetropes. Progressing myopes experience more and more transient myopia over time, but not the stable myopes.
  
  "These findings may be attributed to impaired sympathetic function in the subjects with myopia. It is speculated that with repeated cycles of near work, residual NITM may contribute to the progression of permanent myopia."
  

If near stress persists and remains unmanaged, then things become a bit more serious:

• The inward tension induced by the ciliary, together with the anterior expansion of the crystalline lens, induces a forward intraocular pressure to the aqueous humor, and then to the cornea. Over time, if this pressure is uniform across all meridians, then anterior axial elongation (i.e., general corneal steepening) could occur. If this pressure is not uniform, then the cornea is still deformed, and we refer to this now as corneal astigmatism.

• The tension and pressure inside the eye creates more intraocular fluids and heat inside the eye. In particular, the gel in the vitreous humor heats up and some gel would start to liquefy and move around. These little organic debris are usually harmless (and naturally occurs with age anyway), but if they intersect the light rays going towards the macula, then one might see some little transparent "objects" flying around. These "objects" are colloquially referred to as floater, and these vitreous debris would occur more with higher myopia. Some details by Morita et al.:
  

  liquefaction of the vitreous begins at a relatively young age in patients with high myopia and progresses with age and axial elongation, thus resulting in a frequent occurrence of posterior vitreous detachment.

• What’s more, the ciliary-induced inward tension, the extraocular-induced vitreous pressure, along with the posterior expansion of crystalline lens, creates a backward intraocular pressure that is relayed from the vitreous humor to the retina, choroid, and then the sclera. The chief symptom of this pressure, the posterior ocular pressure, is a dulll, numb, headache-like sensation in the back of the eye. Over time, this backward intraocular pressure forces stretching in the posterior part of the eye - A phenomenon referred to as posterior axial elongation (or axial elongation for short). For people with fragile or thin connective tissues, this elongation process can occur relatively quickly, and further weakens the connective tissues. For example, Luo et al. found that:
  

  In children, increasing axial myopia was associated with reduced macular volume and thickness.

  And Mallen et al. reported that:
  

  The mean axial elongation with a 6-D stimulus to accommodation was 0,037 mm in emmetropes and 0.058 mm in myopes.

Summary

• Positive accommodation are of at least 3 types: proximal, blur-driven and convergence.
• While different kinds of accommodation and convergence may have different causes, they invariably contribute to near stress.
• If near stress is not managed, then corneal astigmatism, floater increase, axial elongations (i.e., anterior and posterior) and other pathological changes could occur over time. Hepsen et al.:
  

  This myopic shift is primarily associated with an increase in anterior chamber depth, vitreous chamber depth, and consequently in axial length.
• It’s hence imperative to eliminate near stress, by both positivizing the prescription, and doing close work from far.

A saying found in Myopia Manual says it all:

"Any system, under stress, will adapt to that stress, in the direction of the stress, to accommodate that stress"

[caimanjosh]

Good addition to the info on the connection between light and myopia.  I had previously noticed that my distance vision was much better in direct sunlight.  During the previous summer, I took advantage of that by often going up to our building's roof and reading, using my strongest plus lenses, in direct sunlight.  Perhaps this helped my vision out even more than I thought it would, due to the possible chemical changes that the sunlight would cause in my eyes.  I'm looking forward to doing more of that once late spring arrives. 

[OtisBrown]

Hi Tom,

You might wish to include the concept of "negative accommodation" - in your analysis.

http://razlab.mcgill.ca/docs/negativeaccommodation.pdf

I truly believe that a person must look for an "average" of his vision - on his Snellen.   A "clear flash", while not permanent, is a good indication that a person's efforts will be rewarded.  For instance, if a person, wearing a plus, starts at 20/40, and persists, and starts seeing 20/20 in "flashes", that should encourage him.  Continued wearing of a plus, and exercise, can slowly increase the time he sees 20/20, and eventually, the 20/20 does become more stable.

But that must always be a choice of the person who is doing exercise or wearing the plus (to end stress at near).

[CapitalPrince]

sometimes when i look at an image that I can barely see and i actively try to focus on it, I get this feeling as if the lenses in my eyes are being flattened. It's a sharp feeling. This only happens very rarely and most of the time i just feel some discomfort when i look at a blurry image.

The conditions have to be right to get that feeling either the distance or blurry, and you have to actively work on focusing. Only a slight discomfort may not bring permanent changes to the eye. I believe if one can find those optimum conditions, improvements can happen very rrapidly.

[mailliam]

sometimes when i look at an image that I can barely see and i actively try to focus on it, I get this feeling as if the lenses in my eyes are being flattened. It's a sharp feeling. This only happens very rarely and most of the time i just feel some discomfort when i look at a blurry image.

The conditions have to be right to get that feeling either the distance or blurry, and you have to actively work on focusing. Only a slight discomfort may not bring permanent changes to the eye. I believe if one can find those optimum conditions, improvements can happen very rrapidly.

Wow you described the feeling perfectly. It's like my eyes are being stretched from the top and bottom simultaneously.

My vision also becomes super sharp. It's pretty much a clear flash, but I feel more in control of it.

The only times I ever feel like I improve my vision is after getting this feeling. The longer I hold it, the more I feel I improve.  If I just look outside for brief moments (1-3mins) without getting this feeling, I don't feel like I did anything for my eyes at all.

You mention optimum conditions, I feel these are what works for me:

- Natural light
- No glasses
- Objects at varying distances (sharp edges or text are easiest to focus on)
- Fasting (or at least an hour since your last meal)
- Deliberate practice (set out a timer to do this for at least 30 minutes, it usually takes me 10 minutes before I get that sensation you describe).
- A bit of movement (I sway side-to-side a little - activates my periphery)

This really only works if you are already seeing 20/40. You can do the same exercise but while using a normalized prescription (as Frauenfeld recommends) so that your corrected vision is about 20/30 to 20/40.

The biggest hurdle is life. Not being organised to put in that half an hour. Also the tendency to say, 'Ah that's more than enough for today' (that's why I recommend the timer).

I feel I am on the home stretch to my vision improvement journey. It's not a question of if I can get to 20/20 but more a question of when. I won't give a date because I might jinx it (or I get complacent and not put in the work).

P.S - TomLu, I haven't had a chance to go through some of your updated posts but I'm reading them now. Thank you for your contributions.

[CapitalPrince]

I find that blinking, shifting, central fixation triggers this feeling, but still the conditions have to be right and its hard to maintain this positive stimulus

I also noticed that connecting my laptop to the television is also works fiarly well. Since I am a student, i can't spend several hours per day gazzing in the distance of using a snllen

An important concept is "locking in" improvements. Dr. alex wrote an article about this.

If a person uses the plus lens or does active focus for short sessions, I don't think the improvements would stick. Just as if i do close work for short periods of time  and go outside everyday, its very hard to make the eye go down. Only when students put their face in the book for hours at a time does the eye go down.

[caimanjosh]

I'm eagerly awaiting this "theory of hyperopization" post, and also point "b" for "A Causal Model of Myopia Reversal".  Point "a" I think all of us reading this thread know, but I've no idea what the other method would be yet..

[CapitalPrince]

dr frauenfeld says active focus/pushing focus (with or without plus lenses) is the key to reversing myopia and will eventually reverse axial myopia. but results will be slow.

 http://frauenfeldclinic.com/active-focus-the-key-to-reversing-myopia/

[OtisBrown]

Subject: Plus-prevention  is indeed the second-opinion.

In all fairness - here is the advertisement.

http://www.bettervision.com/pr-plus-lens-1.html

But real success - depends on the person "starting early" (20/50) and being persistent for the long-term.

[CapitalPrince]

Hi Tom I like the article on hyperopisation, Whenever i put the text slighty blurred and i blink a lot and i really try to focus on the letters, i feel the sensations that you described.
for some reason blinking and opening the eyes really help. I'm curious what it takes to "lock in" the improvements. I believe doing these for at least an hour at a time willhave the most benefit. 10 minutes of close work here and there will not cause the eyes to go down, only when a child does close work for hours and hours without breaks does his eyes go down.

[CapitalPrince]

Also if a +4D child is given a +4D lens, he would probably be +6/+7 or more in a few years. But its REGARDLESS if he does "near work", since all his work is "beyond inifinity". I never realized this connection before, so it absolutely shows that the eye is bidirectional. But to achieve hyperopisation when the eye is in a myopic State is a lot harder since one has to work at the edge of blur for extended amount of amount to induce a strong enough stimulus for the eyes to change.

[OtisBrown]

Hi Tom,

Subject:  A statement by two medical experts on wearing the "plus" for prevention.

I like to search out optometrists who advocate this new approach.

http://www.bettervision.com/pr-plus-lens-1.html

I am pleased to see this statement.  It makes prevention with the  plus the "second-opinion".

A small update on the prescription section of the close work post.

[CapitalPrince]

hey Tom,

often people who are myopic are noticed to have somewhat "lifeless", bulgy, immobile, and "aloof" looks. Do you know why this happens?

[Tom]

Just sent an email to Richard Anderson, the author of myopiaprevention.org:


Hello Richard. I spent the past week reading your website in its entirety. And here are some comments:

“Myopia forms because the eye grows too long. There is no anatomical method to shrink an eyeball short of cutting part of it off.”

“True myopia (nearsightedness) means that the eyeball has grown too long. That physical change can not be reversed .”

One would think that it’s impossible, but this is exactly what happened in the animal studies, and consistently so.  The animals who were fitted plus lens generally had a decrease in axial length below baseline level - Not just an inhibition of axial elongation.

On the human front, here is a study to be included in the undercorrection section:
http://www.iovs.org/content/51/12/6262.full?sid=dbdaf664-6184-42eb-a8d7-e94008536dce

And this, under the reading glasses section:
http://www.ever.be/view_abstract.php?abs_id=2042

“The web is full of false information and many doctors have become skeptical of any progress in this area because there have been so many false claims over the years. Patients have become skeptical of doctors because they are offered few options besides "wear the glasses" when their eyes and vision get worse.”

I think the medical community haven’t catched up with science in general. It’s only reasonable if patients look somewhere else if solution is nowhere to be found. At least the web opens up the alternative solutions that are otherwise unavailable. There is always the possibility that you or me or anyone else is not entirely correct anyway.

“The problem is getting worse every year and regular glasses are part of the problem.”
“I'm here to say that your doctor should offer you better options.”

Thanks for speaking out on this. I believe that more eye professionals need to change their usual practice before myopia spirals down into a serious epidemic. See http://bjo.bmj.com/content/82/3/210.full

“There is a good theory based on many studies that high carbohydrate diets could make myopia worse.”

You are not the only one suspecting the connection. I’ve tried incorporating some of your references into this post:

http://forum.gettingstronger.org/index.php/topic,538.msg5474.html#msg5474

“Bifocals and PALs are normally used for the condition of presbyopia, which is what happens to everyone, usually in their forties, when it becomes difficult to focus on both distant objects such as street signs and near objects such as a book. The solution is to make the corrective lens have two powers, one for each distance.”

But have you thought about the risk factors making crystalline lens stiffer over time? People should be aware that Bifocal/PAL does not address the causes of presbyopia.

“The reason would be that while wearing the glasses, the person would create a clear central focus so that they could read. This creates a peripheral hyperopia in many eyes, which would create more myopia, just as if the glasses were not being worn. The peripheral hyperopia would be there with or without the reading glasses. “

I think it should be emphasized that defocus changes as one changes the focusing distance as well. This explains why reading glasses won’t work if you read within your far point. I believe that special contact lenses study could be make to fail as well, if the subject were instructed to read very close. There is a difference between relative peripheral refraction, and the actual peripheral defocus in practice.

“Proponents of reading glasses state they should work because they relax the eye while reading, the assumption being that reading by itself causes myopia.”

If they believe that reading by itself causes myopia, why would they even use reading glasses? I think the main reason of using reading glasses is just so that near stress can be eliminated, but that won’t happen if one continues to read very close.

“Everyone became nearsighted before they got their glasses. If no glasses was a cure, there should be no blurred vision to begin with.”

“There is also the fact already mentioned that people become nearsighted before they start wearing glasses so that suggesting not wearing glasses as a "cure" is logically suspect.”

I believe that the logical suspect is that wearing full minus prescription is better than wearing no glasses. I have all the reasons to believe that near stress is the cause of myopia (which explains how people become myopic in the first place), and that traditional minus spectacles would make it worse. I also think that your recommendation is more dangerous than you think: the animals got myopic by wearing minus lens, and when the lens is removed, they recover from myopia. The same thing happens to me, and countless people on gettingstronger.org forum and frauenfeldclinic.com.

“Animals (including people) become nearsighted if they do not have clear vision as they are growing up. An example would be a child born with a cataract, which does not allow clear vision. If the cataract is not removed early, the eye will quickly become very myopic (and still blind). But it has been shown that brief periods of clear vision, as short as one hour a day in monkeys, are able to greatly negate the myopic effects. A corralary in humans may be that full distance correction needs to be worn at least part of every day to prevent myopic progression. If you don't have any glasses, you never have the clear vision that appears protective.”

I thought about this extensively a year ago and I can tell you that it’s not correct. Form deprivation is not the same as unclear vision. Form deprivation myopia occurs when there is occlusion or obstruction to our visual field. If unclear vision causes myopia, then animals wearing plus lens should have become more myopic, but that is the opposite of what happened. Again, even if clear vision is necessary for a brief period every day, I still think that your recommendation is more dangerous than you think.

“One study that was done with under-correction was stopped after two years when it became obvious that the under-corrected students were progressing faster than the fully corrected students. “

My experience suggests that undercorrection alone does not prevent myopia, as we also have to take into account the focusing distance in question. Also, this study did draw some criticisms. See:

a) http://wildsoetlab.berkeley.edu/index.php?title=Controlling_Myopia_Progression_-_A_Confusing_Story

b) http://www.i-see.org/oleary_critique.html

“Due to these factors, many people wear sunscreen on their skin and sunglasses on their eyes. Whether these actions negate or reduce the beneficial effect of being outdoors is not known.”

This is a good point. Using hat outside can mitigate both types of risks.

“Processed carbohydrates are a cheap source of calories and are heavily advertised by the food industry because they are profitable. “

You must have been aware that the same thing applies to the industry of ophthalmic lenses, and the influence they exert on our research studies. It also seems to me that this website is set up to promote orthokeratology and the website orthokdoctors.com. I think myopia is best tackled through myopia rehabilitation (see www.frauenfeldclinic.com).

“there has been no study to show that pseudo-myopia, if not treated, leads to more myopia.“

What if there is no interest in conducting such studies? In fact, we do have countless indirect evidence suggesting that it is the case (e.g., the atropine studies, the studies showing how NITM can increase vitreous chamber depth in susceptible individuals). One just have to seep through the papers.

The idea that pseudomyopia leads to mypia is something that I can witness everyday. After all, research are conducted by humans, who might have all kinds of intentions and biases.

“Scientific thought has a history of both charlatans and subpresssion of alternative viewpoints “

This is why I'm writing to you. Maybe some of the research studies will be regarded as bogus as we look back hundreds of years later, and the charlatans are not necessarily the laypersons.

“Most do so because they haven't seen the studies, but others will elect to ignore them.”

I think there is a possibility that some researches are only conducted to prove their point, some might not be even well controlled, yet some others might have a hidden agenda, but I agree that in general, we shouldn’t deny a study unless we have compelling reason to do so.


Also, I really appreciate the three clauses in your mission statement. This shows that you are an optometrist open to alternative viewpoints, such as the theory and application of myopia rehabilitation through behavioral methods:

http://forum.gettingstronger.org/index.php/topic,538.0.html

All the best,

Tom