Myopia Therapies Based on Accommodation

According to the "Bates – method" (Bates was an American ophthalmologist, first introducing his method in 1903) the prescription of glasses, with which a full correction is achieved, is accelerating the progression of myopia^{163, 164, 165}. This idea, which was claimed to be based on experience, was promoted at approximately the same time by the German ophthalmologist Wiser (around 1900)¹⁶⁶, and the American ophthalmologist Raphaelson 167 applied a similar approach. Their basic ideas, still supported today by many publications and classes^{168 ,169, 170, 171}:

Optometrist Bowan¹⁷² recommends therefore the following easy exercise: "After 20 or 30 minutes of close work, look away from your work to something that has printing on it, like a clock, a poster, a sign outside the nearby window – whatever target you have that has a notable detail on it. While staring at the details, numbers or lettering, tighten your toes downward inside your shoes, then progress up your legs, through your torso, fists, arms and neck, tensing all your muscles intently for about five seconds and then quickly release them all at one time … (The technical explanation for why this works is a basic fact of the brain that when you stimulate the voluntary nervous system as you did, the involuntary system is forcibly relaxed)".

The Bates method actually goes beyond the exercising of accommodation; it is also a method to fight the negative effect of stress on the eye (for more specific reports about the impact of stress on myopia see section 3.13).

The claim of some people that real axial myopia (not pseudomyopia) can be really reversed is very strongly rejected by the scientific world, and hardly any hard facts for this claim can be presented.

The partly related method vision training, also called vision therapy, visual training, behavioral optometry, developmental optometry, is described in section 3.8.

3.2.2.2 Biofeedback

The results of biofeedback exercising¹⁷³ are said by most authors to be limited to improving "visual acuity", but with little effect on refraction, i.e. the myopia^{72, 174, 175}. In the light of the results about image quality (see section 3.3) this improved visual acuity might be able to avoid the progression of myopia.

There is a (rather expensive) "Accommotrac Vision Trainer

" on the market¹⁷⁶, which uses the biofeedback principle.

Notes:
- There is the claim of Accommotrac^® : "Blood pressure and heart rate, for example, can be controlled; so can the ciliary body." Not only this statement will get little approval from cardiologists, but also myopia involves far more than the action of the ciliary muscle. Therefore, the use of this device is questionable.

- The fact that biofeedback appears to improve visual acuity, but not refraction reminds of computer software, with which the sharpness and the contrast of copies of an images can be improved, but - naturally - the "real" picture cannot be improved. How about if biofeedback works somehow similarly? Evaluation of the retinal image is improved, but the retinal image itself stays as before (i.e. no change in the refraction).
NeuroVision

utilizes the abovementioned concept of perceptual learning. A computer-based interface is used to perform a repetitive set of visual exercises for 10 to 12 weeks. Benefits of this treatment have been recently reported (J Refract Surg. 2006 Apr;22(4):406-8).

3.2.2.3 Undercorrection for Near Work, Plus-, Bifocal- and Progressive- Glasses

For information about permanent undercorrection, see section 3.2.2.8.

The principle of this treatment is to avoid full correction, i.e. to avoid full accommodation for (extensive) near work – it was already mentioned in section 1.3.2 that the eye elongates during accommodation, which corresponds with axial myopia.

The concept that plus lenses for near work might help against the onset of myopia in many cases and that undercorrection for near work might help against the progression of already existing myopia follows rather straightforward from the facts that:

The results about emmetropization lead to the conclusion by Wildsoet¹⁷⁷ that "full refractive correction of myopia will lead to accelerated progression" Fitting lenses with zero power in front of myopic eyes, however, led to a recovery from myopia, whereas the application of corrective glasses, (like the fitting of glasses which is usually done!) prevented the recovery from myopia178 (see also section 3.3.5 about emmetropization).

This principle of undercorrection for near work was found to result in a reduction of the progression of myopia, or even to result in a reduction of myopia^{179, 180, 162, 181, 182, 183, 184, 185} In other studies and papers, however, the positive results could not always be confirmed^{14, 162, 186, 187, 188}, or showed a positive effect for the first year of the treatment only¹⁸⁹.

In detail Morgan stated⁷⁴: "The COMET study reported that the progressive addition lenses were more effective with children with lower myopia, lower accommodative responses and closer reading distances, and less effective with children with higher myopia, better accommodative responses and longer reading distances."

Note:
This matches with my suspicion that cases of lower myopia are caused primarily by an "overemmetropization" by intensive near work (see section 3.3.5), but that cases of higher myopia are caused primarily by defects of the connective tissue (see section 3.21 for corresponding conclusions about the treatment). Clearly, both effects will be frequently or even mostly combined.

The issue "undercorrection for near work" can be viewed as a simple problem of the ocular muscles, which are responsible for accommodation, and appropriate emmetropization. It can, however, as well be viewed as a neurological issue. Bowan summarized¹⁹⁰ the stress caused by reading and the positive effect of plus lenses on it: "It actually provokes an avoidance response much like the "fight or flight" response: the heart rate increases; the pupils dilate; respiration can increase; adrenaline is produced; the perspiration rate increases - just as if an emergency were occurring. Two studies demonstrated this (Harmon, Pierce) and also that reading lenses decreased these responses." According to this model, the effect of the plus lenses with the prism is that the stress is reduced by moving the object far enough away (for more information about stress and myopia, see section 3.13.1.)

The following methods for undercorrection are used:

Common additions for near work are between + 1.0 D and + 2.0 D. The relationship between the power of the addition and the reduced strength of the accommodation is shown in the following table:

Potentially negative consequences of permanent (!) undercorrection are discussed in section 3.2.2.8.

At a first look bifocal (or progressive) glasses appear to be an easy solution. Various studies, however, gave mixed results^{193, 194, 195}. Grosvenor et al. stated ¹⁹⁶: "...some showing myopia control with bifocals and some not ... there is evidence that bifocals slow myopia progression in children with nearpoint esophoria, but not in children with exophoria at near [esophoria and exophoria are faulty adjustments of the axes of the two eyes for short distance – at esophoria the axes are too much inwards, at exophoria they are too much outwards, see section 3.4 for details]." Another trial showed that bifocals slowed the progression of esophoric myopes in the first 24 months only, but later on myopia progressed at a similar rate as for children with single-vision glasses; the previously achieved difference in the degree of myopia was maintained, however.¹⁹⁷

Note:
Maybe the "mixed results" mentioned above are caused mainly by the difficulties to fit the "right" bifocal or progressive glasses, take care of the very individual AC/C ratio (see sections 3.4.2 and 3.4.3) as well.

Generally, it is recommended to combine the low plus lenses with appropriate prisms to take care of the vergence¹⁹⁰ (see chapter 3.4.6 about additional prisms.

Special care has to be taken when fitting bifocals to achieve the undercorrection for near work¹⁹⁸:

Kowalski reported some initial problems when using the bifocals¹⁹⁹: " One week after receipt of the study glasses, children wearing PALs [progressive addition lenses] showed a higher frequency of three visual symptoms related to adaptability: looking down from the blackboard and getting items on their desk in focus, blur when reading, and difficulty going down steps." However, "By 1 month, these differences disappeared and the frequency of all visual symptoms remained low and similar for both treatment groups".

Overall, the use of plus glasses (for non-myopes) or plus additions (for myopes) for extensive near work (best with appropriate prism) offers an easy first step to prevent further progression of shortsightedness, or to prevent shortsightedness at all.

And still more logical, you must keep a proper distance for reading – the more distant the paper the better! A larger distance has the same effect as a plus addition (not counting the vergence effects which will be discussed in section 3.4)!

Notes: - Maybe the claimed positive effect of plus glasses can be attributed primarily to the treatment of the esophoria (which is often associated with myopia, see section 3.4.1), and less to the reduction of load for the ciliary muscle by the accommodation.

- Correspondingly, negative lenses and overcorrection with negative lenses increase esophoria¹³⁹. - According to the generally and scientifically agreed fact of emmetropization (section 3.3.5), accommodation (section 3.2), accommodation induced elevated IOP (section 3.6.2) and artificially negative lens induced myopia (section 3.3) the positive effect of adding of plus power for near work is convincing.

- As there were no negative results published for the use of simply adding some plus power for extensive near work, the recommendation should be: Try it!

- If you want to try now the use of plus glasses for near work, you should get glasses from an optician who is fitting the glasses according to the geometry of your face, and you should avoid the simple glasses from the shelf. A report from a reader of this paper indicates that unfitted glasses of this kind can lead to astigmatism, a result that can be explained by the reduced image quality in certain regions of the retina.

- Astonishingly, there is a lot of discussion about plus glasses and bifocals, but hardly anyone is talking about keeping a proper (i.e. not too near) reading distance! Doing near work with a larger distance, however, is equivalent with plus glasses and a shorter distance (not mentioning the potentially disturbing vergence effect of a shorter distance, and the prismatic effect of plus glasses, see section 3.4).

- Nevertheless, it is hardly likely that optical means like this undercorrection for near work alone are enough to fight pathological or progressive myopia. It has to be supported by following the other recommendations, too (see section 4.8).

For older people there is another, additional mechanism of plus glasses / plus additions: With the beginning of presbyopia the lens loses flexibility, it "freezes" its shape (see section 1.4.3). A lens, which is mostly in the accommodated shape, stays in this shape even when the ciliary muscle is relaxed, resulting in the symptoms of myopia. As a consequence plus glasses / plus additions for near work should be helpful for these people, too, because they keep the lens in a more "fardistance- shape". On the other hand, if all the accommodation efforts are taken off from the lens, it is loses its flexibility still earlier.

Moreover, a device called "Myopter

", which is designed to eliminate the accommodative effort, is sold²⁰⁰.

Finally, especially for children the seating position has an impact on the proper reading distance: if the chair is too low with respect to the height of the table the reading distance will be too short, and reading when lying on the belly results definitely in an inadequate distance. As a conclusion to the difficult and complex situation which learning children are facing, Skeffington, who is the originator of behavioral optometry (see section 3.8 about behavioral optometry / vision therapy), stated²⁰¹: "To help children to learn, carefully prescribed learning lenses for use in the classroom are irreplaceable."

National Eye Institute (NEI) Statements

1. Myopia Progression--Effect of Bifocal vs. Single Lenses
In a small preliminary study researchers have found that children who wore bifocal eyeglasses had a slightly slower progression of myopia, or nearsightedness, than children who wore traditional single-vision eyeglasses. These findings appear in the August 2000 issue of Optometry and Vision Science.
The randomized trial was conducted with children between ages six and 12, all of whom had myopia and a condition called esophoria, which is a tendency for the eyes to cross while reading. The researchers found that, after 30 months, the children wearing bifocals had slightly reduced progression of myopia compared with the control group that wore regular eyeglasses.
The researchers conclude that their findings "seem to fall short of what might be considered a substantial benefit" and "do not justify the unequivocal recommendation" of bifocals for all myopic children with esophoria. According to the authors, modest benefits of bifocal use "need to be weighed against the increased cost and the attitude of the parent and child towards bifocals."

2. Statement on the Use of Progressive Addition Lenses vs. Single Vision Lenses to Treat Myopia in Children - Correction of Myopia Evaluation Trial (COMET).
Growth of the eye and the development of refractive state (e.g., myopia) are guided by visual feedback. Studies have shown that images not focused on the retina guide the eye to grow to correct for this lack of focus. Research on animals shows that there is a cascade of signaling mechanisms within the eye and, guided by visual feedback, these signals control the growth of the eye and its refractive state. Many studies have documented that the eyes of animals exposed to continuous retinal defocus become myopic. The rationale for COMET was based in part on these findings.

Researchers found that the three-year progression of myopia in children who wore progressive addition lenses (PALs or no-line bifocals) was slightly less than that of children who wore single vision lenses (SVLs). From a clinical perspective the beneficial effect of PALs was not large enough to recommend a change in the way eye care professionals prescribe glasses for children.

The main result was that the difference in progression of myopia between the PAL and SVL groups after three years was 0.20 diopters (D). Progression of myopia was less in children wearing progressive addition lenses (PALs) by about one-fourth of a diopter. While this modest treatment effect is not large enough to recommend a change in clinical practice for all children with myopia, results of COMET suggest that there may be some children for whom PALs may be beneficial for slowing the progression of myopia. A key observation from COMET is that the treatment effect occurred in the first year and was sustained at the same level over the next two years.
Retinal defocus resulting from poor accommodation (focusing of the eyes) when children with low amounts of recent onset myopia are engaged in close work may be a stimulus for increased eye growth and myopia progression. PALs may slow progression of myopia in these children by reducing retinal defocus. Results from COMET provide some support for the rationale. The difference between the PAL and SVL groups was greater in children with poorer accommodative response and lower amounts of myopia at the start of the study. An additional exploratory analysis combining these two factors showed a three-year treatment effect of PALs of 0.55D in children with both poor accommodative response and a low level of myopia at the start of COMET.

COMET related publications (full text) 1 & 2
Petition to FDA based on COMET results to require eye care professionals to advise parents of children with initial myopia that distance (minus) lenses worsen myopia, and that myopia may be prevented by using reading (plus) lenses for computer usage and other prolonged close work.

3.2.2.4 Intermittent, Short Term Wearing of Plus Glasses

In the sections above evidence was discussed that plus lenses help through undercorrection during near work. There are also very strong indications that intermittent, short-term use is also effective:

It is well known that chicks become myopic by wearing negative lenses (see section 3.3). However, Zhu et al. stated²⁰² that "Even when chicks wore negative lenses for the entire day except for 8 minutes of wearing positive lenses, the eyes compensated for the positive lenses, as though the negative lenses had not been worn. ... Brief periods of myopic defocus imposed by positive lenses prevent myopia caused by daylong wearing of negative lenses. .... regular, brief interruptions of reading might have use as a prophylaxis against progression of myopia." Additionally it was told that the use of plus glasses is popular among pilots, for which perfect far-vision is essential²⁰³.
Note:
This reminds not only of the therapy by wearing plus additions (section 3.2.2.3), but also of the brief relaxing exercises, which were proposed by Bates (section 3.2.2.1).

In contrast to the positive results of the experiments on chicks, Morgan stated⁷⁴ that "similar experiments carried out on tree shrews and primates have not been successful." Nevertheless it was expressed in the same paper: "...the recently described properties of the STOP signal [which stops eye growth] evoked by positive lenses offer considerable potential."

3.2.2.5 Plus glasses – are they Effective via Reduced Accommodation or via Modified Vergence?

Wearing glasses (not contact lenses) has not only an effect on accommodation, but generally also on vergence (see section 3.4.5) – and vergence, especially the esophoria (see section 3.4.1) is closely associated with myopia.

From this point of view, there is a significant difference between an increased reading distance, an undercorrection, bifocals or progressive glasses, and plus glasses, e.g. combined with contact lenses if necessary.

Wearing of plus glasses was explicitly claimed to be effective against myopia^{167, 171} (not only for prevention, but also for improving an already existing myopia) and offers the best means to reduce the potentially dangerous esophoria.
Note:
The supporters of the plus-lens-therapy mainly argue on the basis of personal experience only without going into much detail of explanations, i.e. without mentioning its positive effect on vergence. There is, however, a scientific linkage between plus lenses, phoria/vergence, and myopia via the degraded-image-quality-model (see sections 3.3 and 3.4).

3.2.2.6 Comparison of the Various Optical Methods

In Table 5 various optical methods discussed in the sections above, are compared. However, some of the criteria mentioned here will be in subsequent sections. Of special importance appears to be the column "Effect on vergence".

Notes:
- The column "Potential effect on myopia" reflects my personal overall assessment, based on the referenced sections about accommodation and about vergence/phoria.

- -As discussed in detail in section 3.4, myopia is closely associated with esophoria and a high AC/A ratio, which both result in a too-much-inwards-adjustment of the optical axes of the eyes at near focus.

- Soft contact lenses are not associated with a positive impact on myopia (see section 3.19.1) and were therefore not included in the table above.

3.2.2.7 Psychological Problems with Special Glasses for Near Work

The described principle of undercorrection, or bifocal- and plus-glasses is very often hard to accept by people:

With fully correcting glasses there is immediately good vision for all distances (at least for young people with full range of accommodation), which gives the feeling that "everything is o.k. from now on", and if people don’t worry about the future myopia is no longer an issue. And in general, people don't want to recognize a problem until there is already some damage.

Using undercorrection, bifocal- and plus-glasses people are faced permanently with the issue of non-perfect vision. This will be tolerated only, if people are concerned about the future, but many people are hardly willing to face problems in general, and still less to face problems which arise in the future.

Therefore, this therapy may meet with resistance.

In the best case, people who are at risk to become myopic will use plus glasses for extensive near work already before becoming myopic to prevent myopia. I guess, however that people will read my book (and everything else about myopia) only if the problem is already there (it's like with everything in life, "damage makes you wise" - a translation of the German proverb "Aus Schaden wird man klug").

On the other hand, people who are already myopic may have the feeling that "now, being myopic anyway, it does not matter anyway." This group, however, should be fully aware that high myopia is not just a lens-related optical problem, but that it can have very serious consequences for the general preservation of the eyesight, potentially leading to blindness (see section 1.7).

3.2.2.8 Permanent Undercorrection instead of Undercorrection for Near Work only

The effect of permanent undercorrection appears to be still disputed, as some controversial reports show:

There is some blur adaptation when people with myopia do not use full distance correction, as Rosenfield et al. wrote²⁰⁷: "A significant change in letter and grating visual acuity was observed during the course of the 3-h period of sustained blur..." and "However, no significant change in refractive error, measured using noncycloplegic autorefraction, was found. These results demonstrate significant blur adaptation in subjects with uncorrected myopia, which does not result from a change in refractive state. We hypothesize that the improvement in visual resolution results from perceptual adaptation to the blurred image, which may occur at central sites within the visual cortex." In other words, people who do not use proper correction might feel they are improving their myopia, but in fact, they are not.

Notes:
- On one hand the result that undercorrection increases myopia matches the results given in section 3.3, where optical blur, which is a consequence of permanent undercorrection, is shown to be a cause for myopia as well.

- On the other hand the result that undercorrection reduces myopia matches the results given in section 3.3, where plus lenses caused the eyes of animals to shorten, i.e. to become hyperopic.

- Maybe the relation between the time which is spent for near work and which is spent for distant viewing could explain this conflict: It may depend simply, whether the eye can spend enough time with successful focusing (i.e. when it has a sharp image), or whether for a very long time the eye detects a blur image only.

Permanent overcorrection is increasing myopia without any doubt (see section 3.3 as well).

Until there is a definite answer to the question about permanent undercorrection, the conclusion is that it is best for the eye

Obviously, bifocals are matching these conditions best, but it appears to be hard to make use of this concept, as there are some ophthalmologists, optometrists and opticians, who do not like to apply this concept, and these bifocals are not so easy to fit properly.

Therefore a solution without these bifocals is to use glasses with proper distance correction permanently, but to exchange them for glasses with a plus addition for longer time near work like reading, doing homework, making handicrafts, writing tests in school etc.

Very careful determination of the right refraction is therefore an extremely important issue (see section 1.11).

3.2.2.9 Is the Accommodation System Getting too Lazy by the Plus Glasses?

There could be the argument that in the long term the lack of accommodative effort is making the accommodative system unable to work any more, i.e. to accommodate properly for near vision.

Notes: Counter-arguments are:

• Many people are doing hardly any near work during their daily life and they are still able to focus exactly for near if it is appropriate. Our ancient ancestors did not do nearwork of extremely long duration like for reading at all. On the other hand, they did fine handicrafts like embroidery, leather plaiting, flint chipping etc. – many dark winter days were spent like this.

• Even if plus glasses are used for extensive near work there are many occasions in daily life where short term accommodation for near is taking place without the usage of the plus glasses, which results in permanent training anyway.

3.2.2.10 Summary of the Accommodation Based Therapies

A schematic overview of the accommodation- based therapies is shown in Figure 7 (below)

In spite of the fact that the promoters of this method argue mainly from personal experiences only, scientific explanations for its potential efficiency exist¹⁷⁸ (see also sections 3.2.1 and 3.4).

Note: Even if some of the claims of the promoters of the accommodation-based therapies appear to be exaggerated ("reversing of myopia is always possible"), there is no doubt that any reduction of accommodative stress (like large reading distance, plus lenses, bifocals, good illumination) is helpful and necessary to avoid the appearance of myopia and to stop the progression of myopia.

Additionally, no negative side effects of these "therapies" were mentioned anywhere in the literature, therefore: try it!

In one paper, however, Schaeffel et al. stated⁶⁶: "If variable genetic factors are major determinants of myopia in children, then modifying the visual experience (that is, doing near work with reading glasses), may not be very effective in inhibiting myopia development."

Note:
The logic of this statement appears to be questionable, as the following, controversial statement says: "... results indicate a high heritability for ocular refraction and its determiners and thus suggest that environmental impact on refraction is not significant. However, the epidemiological association between educational length (near work) and myopia, the evidence of increasing myopia prevalence within a few generations, and the theory of gene-environment interaction imply that some individuals might be genetically liable to develop myopia if exposed to certain environmental factors."⁷⁵ Extra glasses for reading are creating a modification of these environmental factors, and therefore may be effective in protecting against myopia.

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