الفهرس Only 14 pages are availabe for public view
 |  | from | 166 |  |  |
| | | from | 166 | | |
Abstract
At the time of birth, the visual system is immature and visual acuity is less than in a normal adult. It is developed by the individual on the basis of experience. Development of the visual
pathway in the central nervous system requires that the brain receive equally clear, focused images from both eyes. Any ocular process that interferes with or inhibits the normal development of
the visual pathways in the brain may result in poor vision, that is, amblyopia.
According to the National Eye Institute (NEI); Amblyopia, or lazy eye, is the most common cause of visual impairment in children and often persists in adulthood. It is reported to be the
leading cause of unilateral vision loss in the 20-70 year old age group, with a prevalence of 1-4 % in various studies. Amblyopia is primarily a cortical phenomenon, caused by unequal
competitive inputs from the two eyes into primary visual cortex area 17.
Anisometropia is the leading cause of amblyopia and occurs because of unequal refractive error between the 2 eyes. In general, anisomyopia of more than 2 D, anisohyperopia of more than 1 D,
and anisoastigmatism of more than 1.5 D may result in amblyopia.
It has been shown that the level of the anisometropia plays a direct
role in the final outcome of amblyopia therapy.
Classic teaching is that amblyopia must be detected early and the pathology (strabismus, media opacity, or asymmetric refractive error) must be addressed prior to beginning treatment
for amblyopia. Children with anisometropia are treated conventionally with spectacles and/or contact lenses. However, in some children spectacle correction may lead to aniseikonia, and children may become contact lens intolerant, which leads some ophthalmologists to suggest refractive surgery in these cases. By
reducing anisometropia, refractive surgery has been reported to improve spectacle tolerance, facilitate amblyopia therapy, and enhance binocular vision. Each case should be fully assessed to select the appropriate operative procedure. Each technique has its own advantages and drawbacks which should be weighted before taking decision.