A comparative study of central corneal thickness (CCT) and intraocular pressure (IOP) in University of KwaZulu-Natal students of Black and Indian ethnicity*

Abstract

Thisstudy compared central corneal thickness (CCT) and intraocular pressure (IOP) of Black and Indian students from the University of Kwa-Zulu-Natal. Two hundred (100 Black and 100 Indi-

an) participants of both genders aged 18-25 years (mean and standard deviation; 20.1±1.6 years) participated in this study. CCT and IOP were measured for the right eye of each participant using a Tono-Pachymeter (NT530P) and a Goldmann applanation tonometer (GAT) respectively. Data was analyzed with descriptive, t-test and Pearson’s cor-relation statistics. In the total sample (N = 200), the mean CCT value was 519.5 ± 38.6 μm and CCT was higher in the Indians (526.5 ± 37.2 µm) than in the Blacks (512.4 ± 38.9 µm) (p = 0.01).  Also, it was higher in the females (522.3 µm) than in males (516.7 µm), but the difference was insignificant (p = 0.07). The mean CCT was higher in the Indian males (520.1 µm) than in the Black males (513.2 µm), but the difference was insignificant (p=0.39).  However, it was significantly higher in the Indian females (533 µm) than in the Black females (511.6 µm) (p = 0.003). In the total sample, the mean IOP was 14.6 mmHg and IOP was greater in Indiansthan Blacks (mean = 15.3 ± 2.9 mmHg and 13.8 ± 2.6 mmHg respectively) (p = 0.01). Also, the mean
IOP (N = 200) value was slightly higher in the females (14.7 mmHg) than in males (14.5 mmHg) (p = 0.51). The mean IOP was higher in the Indian males (15.0 mmHg) than in the Black males (14.0 mmHg) (p = 0.07) and the mean IOP value was
higher in the Indian females (15.7 mmHg) than in the Black females (13.6 mmHg) (p < 0.001). The higher mean IOP value in the Indian than Black participants was attributed to the higher mean CCT values. A positive, but inconsistent association between CCT and IOP was found in this study, the coefficient in the total sample (r = 0.382, p = 0.000), in the Blacks (r = 0.196, p = 0.05) and in Indians (r = 0.498, p = 0.000). A national population study comparing CCT and IOP in the various South African ethnic groups is recommended. Cognizance of these differences should be taken in the diagnoses of glaucoma in these ethnic groups. (S Afr Optom 2012 71(4) 171-177)