Anisometropic

Anisometropic is an adjective describing a refractive condition in which the two eyes have unequal refractive power, producing different focusing strengths. In clinical use, anisometropia refers to a difference in refractive error between the eyes. The difference is measured in diopters, and many clinicians consider a difference of about 1 diopter or more to be clinically significant, though thresholds vary by age and measurement method.

Causes of anisometropia include disparities in axial length, corneal curvature, or lens power between eyes. It can be present from birth (congenital), develop during childhood, or result from ocular interventions or trauma. Differences in hyperopia, myopia, and astigmatism between eyes contribute to the condition.

Symptoms may include blurred vision, eye strain, headaches, and difficulty with depth perception. In children, the brain may suppress the image from the more ametropic eye, leading to anisometropic amblyopia if uncorrected.

Diagnosis relies on a comprehensive eye examination with cycloplegic refraction to measure the refractive error in each eye, along with keratometry and assessments of binocular function. Retinoscopy or autorefractors quantify interocular differences, and dilated fundus examination rules out other pathology.

Treatment centers on providing balanced, clear vision in both eyes. This typically involves correcting each eye’s refractive error with spectacles or contact lenses; contact lenses are often preferred in children to reduce image disparity and promote binocular vision. If amblyopia is present, patching or penalization therapy may be used. In adults, refractive surgery or lens implants can be considered to equalize refractive power.

Early detection and correction improve the likelihood of normal visual development and binocular function. Untreated anisometropia increases the risk of persistent amblyopia and related visual problems. See also anisometropia and amblyopia.