Analysis of corneal biometry in a black South African population

Background: Corneal astigmatism and central corneal thickness are important clinical parameters for cataract surgery and glaucoma, respectively. There is very little research on the central corneal thickness and the prevalence and pattern of corneal astigmatism in black South Africans. Aim: The aim of this study was to analyse the corneal astigmatism and central corneal thickness of a large population of black South Africans awaiting cataract surgery. Setting: The study was conducted at St John Eye Hospital, Soweto, South Africa. Methods: This was a cross-sectional study of a database of adult black patients awaiting cataract surgery. Biometric data was captured using Sheimpflug Imaging (Nidek AL-Scan). Steep corneas (K readings of more than 48 D) or abnormally thin or thick corneas (central corneal thickness [CCT] 650 μ m) were excluded from the study. Results: A total of 3231 eyes of 1713 patients were included in this study. Patient ages ranged from 18 to 99 years with a median age of 67 years (interquartile range [IQR] 57–75 years). There were more females ( n = 1064) than males ( n = 649). The median central corneal thickness was 494 μ m (IQR 473 μ m–516 μ m). The median corneal astigmatism was 0.92 dioptres (IQR 0.55–1.43 dioptres). A large proportion (45%) of our study sample patients had 1 dioptre or more of corneal astigmatism. Conclusion: This analysis of corneal biometric data revealed that a large proportion of black South African patients awaiting cataract surgery have thin corneas and visually significant corneal astigmatism.