Case report: Mirror-image hypermetropic anisometropia in nontwin brothers

Mirror-image is a term to describe a physical characteristic of some identical twins that appear asymmetrically on opposite sides as if they are looking in a mirror. Mirror-image anisometropia in monozygotic twins was previously reported in the ophthalmic literature. In this article, we describe a case of mirror-image hypermetropic anisometropia in siblings aged 8 and 5 years old. Nontwin brothers, 8 and 5 years old, with mirror-image hypermetropic anisometropia, were referred to the pediatric ophthalmology clinic. Corrected distant visual acuity was 20/20 (ocula dextra [OD]), 20/60 (ocula sinistra [OS]) in the older brother, and 20/50 (OD), 20/20 (OS) in the younger brother. Cycloplegic refraction was + 3.5 - 1.25 × 180 (OD), +7.75 - 1.5 × 30 (OS), and + 7.0 - 0.75 × 20 (OD), +2.0 - 1.0 × 170 (OS) in the older and younger brother, respectively. The axial length difference between the two eyes was 1.47 mm in the older and 2.01 mm in the younger brother. Hypermetropic anisometropia that may lead to anisometropic amblyopia may happen in nontwin brothers. This emphasizes the importance of complete ophthalmologic examination in the siblings of all patients with anisometropia.