ambliopia

Amblyopia, sometimes spelled amblyopia, is a neurodevelopmental disorder of vision in which reduced visual acuity develops in one eye (or rarely both) during infancy or early childhood and cannot be corrected by glasses. It arises from abnormal visual experience during a critical period of visual development and is not due to an organic eye health problem in the affected eye.

Causes include strabismus (misalignment of the eyes) leading to suppression of input from one eye; anisometropia (different refractive error between the eyes) causing the brain to favor the clearer image; high refractive errors that are uncorrected; and deprivation from anything that blocks the visual axis, such as cataract or severe ptosis. Amblyopia is commonly categorized as strabismic, refractive, or deprivation amblyopia.

Pathophysiology centers on disrupted binocular development. When one eye provides inconsistent or blurred input during the brain’s critical period, the visual cortex prioritizes the other eye, leading to suppression, altered neural connections, and reduced acuity in the affected eye. Although the underlying eye may appear normal, the brain fails to develop normal vision through that eye.

Diagnosis relies on finding reduced best-ccorrected visual acuity in one eye that remains even after appropriate refractive correction, often with accompanying strabismus or anisometropia. Evaluation includes cycloplegic refraction, measurement of visual acuity appropriate for age, and assessment of ocular health and alignment.

Treatment aims to restore balanced visual input and improve acuity. It typically involves correcting refractive error with glasses, plus occlusion therapy (patching the better-seeing eye) or pharmacologic penalization (atropine drops) to encourage use of the affected eye. Treatment is most effective when started early, ideally before age 7 to 9, and requires good compliance and regular follow-up. Prognosis varies with age and severity; some improvement is possible with substantial residual risk if treatment is delayed. Prevention focuses on early vision screening and prompt management of refractive errors and strabismus.