esotropia

Esotropia is a form of strabismus in which one or both eyes turn inward toward the nose (inward deviation). It is also known as convergent strabismus. The deviation can be constant or intermittent and may be present from infancy or develop later, appearing unilateral or alternating.

Subtypes include infantile (congenital) esotropia, accommodative esotropia due to uncorrected hyperopia, sensory or decompensated esotropia from vision loss in one eye, and intermittent or variable forms. Infantile esotropia typically appears within the first six months and is usually a large, constant inward turn. Accommodative esotropia often begins in early childhood and can resolve with appropriate refractive correction.

Diagnosis relies on a clinical eye examination. Tests include cover-uncover and prism cover tests to measure misalignment, assessment of eye movements, refraction, visual acuity, and evaluation of binocular function and stereopsis. The corneal light reflex (Hirschberg test) may show inward deviation.

Treatment depends on subtype. Correcting refractive error with appropriate glasses is first-line for accommodative esotropia. Prisms or occlusion therapy may help some patients. Persistent or large-angle deviations are usually treated with strabismus surgery to weaken the medial rectus and/or strengthen the lateral rectus; botulinum toxin is an alternative in some cases. Early treatment helps preserve binocular vision and reduce amblyopia risk.

Prognosis varies with age at onset and access to treatment. With timely management, many children achieve proper alignment; some may retain reduced stereopsis or require ongoing follow-up for refractive changes and alignment.