AMBLYOPIA
Amblyopia denotes “decreased visual acuity due to lack of a clear retinal image and cortical suppression of the defective image, during developing phase of visionquot;. It may be unilateral or bilateral.
Important characteristics of amblyopia (d/d with amaurosis, i.e. blindness) are as follows:Amblyopia occurs only in young visually immature children (lt;10 years), due to factors which prevent normal development of visual acuity, i.e. misaligned visual axis (strabismic amblyopia), high refractive errors (ametropic amblyopia), unequal refractive errors in two eyes (anisometropic amblyopia) and media opacities, e.g. cataract (deprivational amblyopia).
It is usually asymptomatic, not associated with sufficient organic abnormality to explain diminished visual acuity on ophthalmic examination.
It is rapidly reversible in young children if causative factor is eliminated, but becomes permanent in longstanding cases.
Other common visual image defects include:
Nyctalopia (Night-blindness) indicates defective function of the rods, seen in vitamin A deficiency, early retinal disorders, e.g. retinitis pigmentosa and as a hereditary condition.
Diplopia (Double-vision) indicates mal-alignment of visual axis, seen in strabismus, myasthenia gravis, orbital asymmetry, e.g. proptosis and raised ICP.
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