See also comment(s) by Cynthia Roberts •
PURPOSE: To investigate the difference in corneal hysteresis (CH) and corneal resistance factor (CRF) between Indian and Chinese populations. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Three hundred eighty-two Singaporean Indian persons and 764 Singaporean Chinese 50 years of age or older were included from the Singapore Indian Eye Study and Singapore Chinese Eye Study, respectively. METHODS: Participants underwent standardized systemic and ocular examinations and interviewer-administered questionnaires for risk factor assessment. The CH and CRF were measured with the Ocular Response Analyzer (Reichert Ophthalmic Instruments, Buffalo, NY). Information on genetic ancestry was derived using principal component analysis. Linear regression models were used to investigate the association of CH and CRF with potential risk factors. MAIN OUTCOME MEASURES: Corneal hysteresis and CRF. RESULTS: After excluding participants with a history of intraocular surgery, a diagnosis of glaucoma suspect or glaucoma, refractive surgery, or presence of corneal abnormalities, CH and CRF readings were available for 382 Indian persons. For each Indian participant, 2 Chinese participants were selected and matched for age and gender (n = 764). There were no differences in the clinical measurements of CH (10.6±1.6 mmHg; P = 0.670) or CRF (10.3±1.7 mmHg; P = 0.103) between the ethnic groups. However, after adjusting for covariates, Indian persons had, on average, 0.18-mmHg higher CH levels than in Chinese (95% confidence interval [CI], 0.02-0.38; P = 0.031). Consistently, CH level was correlated significantly with genetic ancestry in the Southeast Asian population. Corneal resistance factor level was not associated independently with self-reported ethnicity (95% CI, -0.10 to 0.29; P = 0.335). CONCLUSIONS: Chinese have lower CH than Indian persons, and this disparity may reflect biomechanical differences of the cornea.
Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Republic of Singapore; Ophthalmology and Visual Sciences Academic Clinical Program, Duke-NUS Medical School, Singapore, Republic of Singapore.Full article