Myopia

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 tim

What cause 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 .

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 still ring true today.Dutch ophthalmologist F. C. 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 elongation explained? These factors may come under consideration:

Pressure of the muscles on the eyeball in strong convergence of the visual axes;
Increased pressure of the pressure of the fluids, resulting from the accommodation of blood in the eyes in the stopping position;
Congestive processes in the Fundus 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.