الفهرس Only 14 pages are availabe for public view
 |  | from | 107 |  |  |
| | | from | 107 | | |
Abstract
Amblyopia is a disorder of the eye that is characterized by poor blurry vision in an eye that is otherwise physically normal or out of proportion to associated structural abnormality (McKee et al., 2003).
Amblyopia is a major public problem it has been estimated to affect 1 to 5 percent of the population its thought to develop early in life during the critical period of visual development (Rodrigues, 2007).
There are three primary types of amblyopia : anisometropic, strabismic and deprivation amblyopia. Anisometropia refers to a difference in refractive errors between the two eyes in any meridian of greater than 1.0 diopter. Aniosmetropic ambylopia occurs in children having a difference in refractive errors between the two eyes typically myopia, hyperopia or astigmatism, and occurs in the more ametropic eye (Donahue, 2007).
Anisometropia may produce amblyopia by causing loss of foveal resolution in the less focused eye (suppression scotoma), or by loss of stereo acuity and binocular function. Studies of normal human subjects have demonstrated that induced anisometropia greater than 1 diopter causes abnormalities in resolution and induction of suppression scotoma (Weakly et al., 2000).
Larger magnitudes of simulated anisometropia in normal subjects produce larger suppression scotomas. Suggesting that foveal suppression in the defocused eye may be the cause of decreased stereopsis (Legras et al., 2001).
A similar impact of increasing levels of induced anisometropia on stereopsis and binocular vision has been demonstrated by Oguz and Oguz (2000).