Corneal Curvature and Refractive Error Measurements in a South African Black Population

Abstract

Abstract: : Purpose: Corneal curvature is one of the ocular components that influence the refractive status. Currently no data on corneal curvature and its comparison to refractive status have been reported for the South African Blacks. This study reports the corneal radius of curvature and refractive error among black South Africans. Methods: Three hundred subjects without corneal and lenticular pathologies participated in this study. Their ages ranged from 20-70 years with an average age of 45 years. The radius of curvature and the refractive error were measured using the Canon RK-2 autokeratometer/refractor. The refractive error and the corneal curvature were compared for the right eye only. Results: The corneal radius of curvature ranged from 39 to 46.50 D. The mean corneal power was 43.20 / -0.31 x 92. There was no change in corneal curvature with age. The spherical equivalent ranged from +5.00 to -6.00 D. The mean refraction was +0.12 / -0.30 x 83. There was a shift toward more hyperopia with increasing age. Although hyperopes tended to have flatter corneas than the emmetropes and myopes, the difference was not statistically significant. Conclusion: The distribution of the corneal powers resembled a normal distribution while for refractive errors, the distribution was leptokurtotic and skewed toward hyperopia. There was low corneal and spectacle astigmatism in this population. The corneal radius of curvature was comparable to the reported values from studies on other racial group.

Keywords: 542 refraction • 354 clinical (human) or epidemiologic studies: prevalence/incidence • 352 clinical (human) or epidemiologic studies: natural history