Near-sight or myopia is one of the most common vision problem and will touch the lives of almost half the population at one point or another. Initially you can see things around you quite clearly. It’s only things at a distance that are blurred. Usually it starts during the school years when you begin to realize that you have trouble seeing what is written on the board. Initially it is something you can cope with but soon it becomes more of a problem and your eyes are tested and fitted with glasses. However, as you begin to wear glasses the myopia tend to progress and get worse and you need to have stronger correction in order to see comfortably. Soon you are wearing the glasses all the time even for things where you can see perfectly well without the glasses.
What causes myopia?
The theories abound about what causes myopia. The loss of distance vision has been known since ancient time. The Greek concept of myopia was that too little spirit of vision poured out from the brain and hence was too feeble to extend to a distant object. However, not much attention was paid to vision problems until mid 19th century. Interestingly enough during the first half to the 19th century the use of glasses were discouraged. They were thought to aggravate the existing problem and to be harmful.
During the 1860’s German ophthalmologist Herman Cohn had observed that myopia increased as children progressed through school. In 1866 Dr. Chon published his study of the eyes of 10,000 children attending the schools of Breslau. He arrived at what seemed a reasonable conclusion: namely, that use (and particularly abuse) of the eyes was what caused myopia. Cohn’s theory dominated for the next 50 years and a crusade began for better conditions of visual hygiene in schools.
Dutch ophthalmologist Donders thought that myopia occurred as a result of prolonged tension of the eyes during close work and elongation of the eyeball. In “On the Anomalies of Accommodation and Refraction of the Eye” (1864) Donders writes:
“How then is this prolongation explained? Three factors may here come under consideration: 1 Pressure of the muscles on the eyeball in strong convergence of the visual axes; 2. Increased pressure of the pressure of the fluids, resulting from the accommodation of blood in the yes in the stopping position; 3 Congestive processes in the fondus oculi, which, leading to softening, even in the normal, but still more under the increased pressure of the fluids of the eye, give rise to extension of the membranes. That increased pressure and the extension occurs principally at the posterior pole, is explained by the want of support from the muscles of the eye at that part..” (pp 343)
Until equipment became available to accurately measure the size of eyeballs in vivo it was believed that the cilliary muscle weakened and could no longer focus the lens. This theory is still offered as the explanation by many eye-care professionals. Ultrasound scans have objectively shown that with high degree of myopia there is an elongation of the eyeball. What causes that elongation is a matter of opinion. Some researchers thought that the problem was with increased pressure in the eye. Kelly et al. (1975) refer to myopia as “Juvenile expansive glaucoma.” However the pressure theory is unlikely since both coughing and an increase in body temperature causes an increase in the intraocular pressure.
A more plausible theory is offered by Peter R. Greene in his Ph.D. thesis titled “Mechanical Aspects of Myopia,” (1978). Greene evaluated the stress experience on the eyes based on engineering principles. In myopia only the back of the eyeball is elongated. The forward portion remain normal. Eyes start out being approximately round but slowly, typically over a 10 year period from age 8 to 18, the posterior sclera slowly begin to take the shape of a prolate spheroid. Greene examined the stress forces on the sclera by accommodation, convergence, vitreous pressure and the external eye muscles. He concluded that the mechanical effects of convergence completely dominate those created by accommodation, even through both occur simultaneously when the eyes focus on a very close target. His calculations showed that the total stress experienced by the posterior sclera is the sum of the stress induced by intraocular pressure and by the oblique muscles. Greene found that the region between the two oblique muscle attachments is subject to tensile strength much higher than those at any other locate of the eyeball. This theory, therefore, could account for the axial lengthening of the eyeball that occur in high myopia.
New York ophthalmologist William H. Bates M.D., (1915 and 1918) after four years of research into accommodation and focusing of the eye he, like Peter Greene, came to the conclusion that the oblique muscles are a major factor in focusing the eyes and the ciliary muscle and the lens are only of minor importance.
Since there are so many ways of classifying myopia, lets make it simple and think of the causes of myopia as “Functional Myopia” and “Structural Myopia.”
The Structural Myopia theory consider genetic factors to be the primary cause of myopia. Goldsmidt (1968) provides an extensive review of the literature on genetics in myopia. He concludes that genetic factors are important, but there are several types of myopia with different genetic patterns. Other researchers have found no basis for the inherited myopia theory.
Functional myopia comes about when you are using your eyes too much for near work. A lot of reading where you for many hours a day keep your focus more or less within half a meter. Like working with a computer all day. It goes back to Herman Chon’s observation from 1866 that overuse of the eyes for near work is the main cause for myopia. Essentially you are gradually training your eyes to focus only on near objects or neglecting to exercise your distance vision. For example animals raised in a close environment develop myopia. There is solid scientific evidence that the environment influence eyesight.
William H. Bates M.D. (1915) suggested that myopia come about because of mental strain. Specifically, tension held in the oblique muscles that form a belt around the eyeball. Peter Green’s investigation in 1978 in effect confirm Bates findings 63 years earlier.
This actually makes sense when you think about how vision problems are in different parts of the world. In native of tribal parts of the world where there is not such a great emphasis on reading and book learning vision problems are virtually non existent. Garner et al. (1985) examined 977 Melanesian school children between the ages of 6 and 17 on the Pacific Island nation of Vanuatu. In two examinations conducted in 1985 and 1986 they found myopia greater than 0.25 diopter in only 1,3 % (1985) and 2.9 % (1986). In other words everyone has good eyesight.
In contrast Ko (1984) reported prevalence of myopia in the Taiwanese cities of Taipei and Koachoung to be 28 % in primary school students, 67 to 71 % in junior high school students, and 81 89 % in senior high school students. Medical school students at the National Taiwan University were 91.5 %.
Life on a pacific island is very different from the pressure excerpted on Chinese students. First, learning to read and write the Chinese character script takes many, many hours of concentrated effort. Second, the preparation for the very strict examinations that is the foundation of the Taiwan school system. In terms of vision the children on Vanuatu are using their eyes to look at things at all distances and are therefore more likely to be able to maintain their natural clear eyesight. Now, compare this to the children in Taiwan where they start the task of learning to write and read at 4 of 5 years of age. Concentrating on writing 100 perfectly formed characters, and in exactly the same size, which require a lot of concentration and predominantly focus their eyes on their books, thus overusing their eyes at the near focus, and that is likely to cause mental strain and subsequently the onset of myopia.
The Vision Training approach for Myopia varies depending on the degree of nearsight you have. For less than 2 diopters or less the exercises mainly consist of activities encouraging your eyes to focus further and furter away and notice smaller and smaller objects. To restore your natural clear vision from 2 diopters or less takes a few days or a week or two in most cases. There are people who have regained as much as 3 diopters in as many days.
To recover your normal vision from 3 diopters of more is a longer proceces which involves wearing reduced prescrition glasses, so your eyes have room to work. Also you have to spend 5 mins. exercising your eyes about 10 times a day. In total you need to allocate one hour a day to your eye exercises.
The exercises varies depending on what stage you are in. With high degree of Myopia - 5 to 10 diopters or more - most people can achieve 0.5 diopter or even 1 diopter improvement per month. This improvement is directly related to the amount of effort you put in. No exercise, no improvement.
There are people who have regained as much as 6 diopters in a year. In other words they have recovered more Myopia than most people have. Vision Training is effective in the same way weight reduction or fitness programs are effective. They work as lon as you do. With eyesight you will be please to know that the improvement tend to last. Your Myopia seldom regress after you have regained it.
Of course it is a lot
easier to recover just a few diopters than to go from say 8 diopters to natural
clear eyesight. However, the good news is that it is possible for
you to do.