With myopia, the eye’s focusing mechanism when naturally relaxed, results in an image that is focused in front of the retina instead of onto it. This could be caused by the cornea protruding too far away from the eye or from an excessive elongation of the eye structure itself. The myopic condition allows nearby objects to be seen clearly but distant objects appear blurry.
By clinical appearance, myopia can occur in the form of simple myopia, nocturnal myopia (occurring at night), pseudomyopia (myopia not associated with a defective focusing mechanism), degenerative myopia (associated with a breakdown in the eye’s refractive components) and acquired myopia (myopia without genetic influence).
How It Arises
The development of myopia commonly involves the influence of genes coupled with a reaction of the eyes to environmental stress. Extensive exposure to television and computers or near work like reading may trigger the onset and subsequent progression of myopia. Scientists have found that changes in a specific gene known as PAX6, have been shown to contribute to the development of myopia. It is also likely that excessive near work without breaks, results in an inflexibility of the ciliary muscles to control the lens for focusing distant objects. Other implicated factors are diet, nutrition and even breathing patterns.
The severity of myopia is implied by the optical power of the corrective lens used to aid the eye in focusing distant objects onto the retina. This power is measured in diopters. An optical power of 6 diopters or more is considered high and consequently associated with severe myopia. Severe myopia can, if left untreated, lead to a greater risk of developing eye problems like floaters, retinal detachment and glaucoma.
Correcting the condition
While alternative or complementary therapies like eye exercises and relaxation techniques may improve the condition, eyeglasses, contact lenses and refractive surgery are the mainstay in treating the condition. Corrective lenses are designed with an optical power measured in negative diopters to counteract the positive diopters of the myopic eye. Special rigid contact lenses may flatten the cornea and hence reduce myopia.
Beyond eyeglasses and contact lenses, refractive surgery has come of age in the treatment of myopia. In considering refractive surgery however, it should be noted that the natural development of presbyopia (or ‘Lau Hwa Yan’, discussed in the following pages) later on, actually could provide an advantage to myopes because assistance with artificial aids may not be necessary for a task like reading. Refractive surgery to correct myopia may counter that future advantage.
Nevertheless, refractive surgery is the growing option of choice for myopia. Laser therapy in the form of LASIK surgery, is now the option that is gaining the greatest momentum the world over.
Sudesh Samuel - As a registered pharmacist in Singapore, I practiced for several years at the National University Hospital, a tertiary, teaching hospital, ...
