Everyone knows that watching TV for too long or reading a book all night stress the eyes. If you are young you may not notice this very much. However, your visual system is severely compromised when you do this.
The biological theory of myopia views myopia as the result of genetically determined characteristics of eye tissues, whereas the use-abuse theory views myopia as the result of habitual use of the eye at a near focal length, near-work.
The use-abuse theory implies that myopia is preventable whereas the biological theory does not. Myopia varies over age, gender, race, ethnicity, level of education, social class and degree of urbanization. The explanation of the epidemiology of myopia in the use-abuse theory is that some types of people do more near-work than others.
In a study by the Johns Hopkins University School of Hygiene and Public Health titles Epidemiology of myopia (1980) they data from the Health Examination Survey of 12 to 17-year-olds conducted by the US Public Health Service from 1966–1970, this paper finds that the use-abuse theory can explain at least some of the variance of myopia and much of the socially patterned variance. Of course this raises the possibility that at least some of the myopia extant in a population is preventable.
In 1860 Dr. Choen studied 10,000 school children in Breslau and concluded that over use of the eye was the main reason for visual problems. So this is an old idea that has gained more acceptance.
To experience accommodative strees try this experiment. Look at something for as long as possible without blinking. You will quickly feel that your vision collapses and your vision gets worse. So if you spend the day looking at the computer screen or reading you will lock your visual system into focusing only on the distance to your computer screen or while reading you will lock your visual system into focusing only on the distance to your book. When you do this for days, weeks, months and years you create accommodative stress. Which in turn leads to myopia.
Another aspect of this is the fact that you also have to turn your eyes in and down inorder to focus on your reading material on in the case of children playing video games. The you have to tighten your oblique muscles located in a ring around the back of your eyes. Peter Green, Harward University (1976), studied near sight form a mechanical engineering perspective.
He came to the concluding that myopia, especially the sevefre type, is due to three factors.
One - the thickness of the scelara – if it is very thin then it will be easier to deform due to external pressures.
Two – the internal pressure that maintain the eyes form. The tendency of the eye is to be round since the internal pressure is equal in all directions.
Three – the tension held in the two oblique muscles turn inward and held in that position for long periods. This tension actually create a force extending the length of the eyeball.
Thus creating the physical deformity leading to near sight. By the way each millimetre the eyeball is longer is equivalent to 3.0 diopters of myopia.
So the obvious approach would be to minimize the tension held in the oblique muscles and thus eliminate the force expanding the axial length of the eye. This in turn will actually reverse the stress pattern over the scelara and will more likely lead to a reduction of myopia.
The Vision training approach aim to relax the tension pattern in the eyes as well as to build up the functionality of the entire visual system including the energetic aspects that are not included in optometry.
So we can conclude that maintaining a visual habit that involve not only near focus but also medium and far focus so the natural visual ability is maintained. The few studies (1862 and 1995) that are available about natural eyesight suggest that visual acuity is maintained up to the 70's without any noticeable deterioration. Visual acuity at 75 year was found to be 20/19 or just a fraction better than normal vision. So it is unlikely to be a purely biological or genetically programmed phenomena.
References
American Journal of Epidemiology Vol. 111, No. 2: 220-228
Copyright © 1980 by The Johns Hopkins University School of Hygiene and Public Health THE EPIDEMIOLOGY OF MYOPIA JOHN. ANGLE and DAVID WISSMANN
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