Usually none. Often discovered when decreased vision is detected via visual acuity testing of each eye individually. A history of patching, strabismus, or muscle surgery as a child may be elicited.
NOTE: |
Amblyopia occasionally occurs bilaterally as a result of bilateral visual deprivation (e.g., congenital cataracts not treated within the earliest months of life). |
Critical
Poorer vision in one eye that is not entirely improved with refraction and not entirely explained by an organic lesion. In anisometropic amblyopia, the involved eye nearly always has a higher refractive error. The decrease in vision develops during the first decade of life. Central vision is primarily affected, while the peripheral visual field usually remains normal.
Other
Individual letters are more easily read than a full line (crowding phenomenon). In reduced illumination, the visual acuity of an amblyopic eye is reduced much less than an organically diseased eye (neutral-density filter effect).
NOTE: |
Amblyopia, when severe, may cause a trace relative afferent pupillary defect. Care must be taken to be sure that the light is directed along the same axis in each eye, particularly in patients with strabismus. Directing the light off-axis may result in a false-positive result. |