Unpredicted eye preference in anisometropic children diagnosed late with amblyopia

Background: This study aims to describe a rare phenomenon of anisometropic amblyopia in the emmetropic eye, preferring the hypermetropic eye. Methods: The cohort included all children with anisometropic amblyopia attending a tertiary medical center in 2014–2016 in whom amblyopia was diagnosed in the more emmetropic or myopic eye. The medical records were reviewed for demographic parameters, best-corrected visual acuity (BCVA) for each eye, refraction, treatment, glasses prescription, follow-up, and final BCVA. Results: Four patients, two girls and two boys, met the study criteria. The mean age at diagnosis was 6.8 years (range 4–8 years), and mean follow-up time was 2.6 months (one child was lost to follow-up). Median cycloplegic refraction in the amblyopic (right) eyes was −1.7 sphere (0–[−4.5]) with −0.45 cylinder (0–[−0.75]) in 80°, and in the preferred (non-amblyopic) eyes, +1.75 sphere ([+1]–[+3.25]) with −0.35 cylinder (0–[−0.75]) in 87°. Corresponding mean BCVA values were LogMAR 0.46 (0.3–0.7) and LogMAR 0.02 (0–0.07); mean spherical difference was 4 (1–6.5). None of the children had an additional pathology. Treatment consisted of full cycloplegic spherical refractive correction or the closest possible while maintaining BCVA, with mild modified subjective correction of the cylinder. Patching was also used in three children. Mean BCVA after treatment was 0.20. Conclusion: In rare cases of anisometropia, in which amblyopia is diagnosed late, the eye with hyperopic refraction may be preferred. Clinicians should be alert to this phenomenon as treatment requires some modification of conventional glasses prescription. Further studies are needed to clarify the underlying pathophysiology.