Ocular biometry in an urban Indian population: the Singapore Indian Eye Study (SINDI)

PURPOSE. To describe the distribution and determinants of ocular biometric parameters in adult Singapore Indians. METHODS. A population-based, cross-sectional study was conducted on 3400 Indians aged 40 to 83 years residing in Singapore. Ocular components including axial length (AL), anterior chamber depth (ACD), and corneal radius (CR) were measured by partial coherence interferometry. Refraction was recorded in spherical equivalent (SE). RESULTS. After 502 individuals with previous cataract surgery were excluded, ocular biometric data on 2785 adults were analyzed. The mean AL, ACD, and CR were 23.45 ± 1.10, 3.15 ± 0.36, and 7.61 ± 0.26 mm, respectively. The mean AL/CR ratio was 3.08 ± 0.13. The mean AL was 23.53, 23.49, 23.35, and 23.25 mm in 40- to 49-, 50- to 59-, 60- to 69-, and 700 to 83-year age groups, respectively (P < 0.001). Men had significantly longer ALs than women (23.68 mm versus 23.23 mm, P < 0.001). In multivariate linear regression models, AL was found to be longer in adults who were taller (P < 0.001), better educated (University, P < 0.001), and more apt to spend time reading (P < 0.001). Increasing CR was associated with increasing height (P = 0.008). AL was the strongest determinant for refraction in all age groups, whereas lens nuclear opacity was a predictor in adults aged 60 to 83 years. CONCLUSIONS. The AL in Indians living in Singapore was similar to that of Malays in Singapore, but longer than that of Indians living in India. Time spent reading, height, and educational level were the strongest determinants of AL. AL was the strongest predictor of SE in all age groups.