Refractive profile in oculocutaneous albinism and its correlation with final visual outcome

Abstract

Purpose: To evaluate the prevalence of refractive errors in different subtypes of oculocutaneous albinism, and to see if there is any correlation between refractive errors and final visual outcome in this population.

Patients/methods: This is a retrospective study of 132 albino patients, ranging in age from 0.5 to 35 years. They were divided into four subtypes: OCA1A, OCA1B and OCA1C, and OCA2. Refractive errors were evaluated objectively by cycloplegic refraction and subjectively in cooperative patients. Best corrected visual acuity was assessed binocularly. Refractive errors were divided into three groups--hypermetropia, myopia and astigmatism--to avoid the use of spherical equivalent.

Results: Refractive errors were mainly astigmatism and hypermetropia. The OCA1A group showed high hypermetropia (≥ 5 dioptres) in 43.4% of patients, reaching significantly higher levels than in other subgroups (p=0.007). Mean visual acuity in logMAR was: OCA1A=0.81, OCA1B=0.64, OCA1C=0.61 and OCA2=0.48. Astigmatism averaged 2.1 dioptres (consistently with-the-rule), and it was homogeneously distributed between all subgroups (53%).

Conclusions: The poorest visual acuity was found in those with OCA1A, which was associated with the highest rate of high hypermetropia (statistically significant different from other subgroups). Astigmatism was the most common visually significant refractive error across all subtypes of albinism. These results may help to clarify the prevalence of refractive errors in albino patients and aid the prediction of visual outcome in this heterogeneous population.