Corneal astigmatism in different ethnic groups in the Western Cape, South Africa.

Abstract

AbstractObjectives To determine whether corneal astigmatism magnitude is equivalent amongst individuals of African black, Mixed race and Caucasian descent in the Western Cape Province, South Africa. Methods Observational, retrospective study including 117 African black, 156 Mixed race and 100 Caucasian participants. Corneal astigmatism parameters were obtained using a Pentacam corneal topographer. Ethnicity was self-reported. Data were collected during an earlier prospective study. All the participants had clinically normal eyes. Results Corneal astigmatism magnitude was equivalent among the three groups. The astigmatism magnitude was − 0.7 (0.7) (median (Interquartile range)) in African blacks, -0.8 (0.7) in Mixed race and − 0.7 (0.6) D in Caucasians. No difference was found for J0 (p = 0.24) and J45 (p = 0.99). Astigmatism type differed between the three groups (p = 0.008). With the rule astigmatism was most prevalent in Caucasians (80.1%), followed by African blacks (71.3%) and Mixed race (65.3%). Corneas were steeper in Caucasians and mixed race, compared to African blacks (p = 0.001). K1, K2 and Kmax respectively, were 42.4, 43.2 and 43.7 for the African black, 43.2, 44 and 44.8 for the Mixed race and 43.2, 43.8 and 44.5 D for the Caucasian group. Thinnest point of the cornea in African blacks, Mixed race and Caucasians were 500 (39), 510 (40), and 534 (45) µm (p < 0.001). Conclusion Astigmatism magnitude is comparable between ethnic groups in South Africa. Hence, we suggest that astigmatism is not influenced by ethnicity. Corneal power and thinnest point differed between the three ethnic groups