Determinants of Anterior Chamber Depth: The Singapore Chinese Eye Study

Purpose: Recent advances in anterior segment imaging have enabled the measurement of novel ocular biometric parameters, such as lens vault (LV), posterior corneal arc length (PCAL), and iris area. The aims of this study were to identify the determinants of anterior chamber depth (ACD) and to ascertain the relative importance of these determinants in Chinese persons in Singapore. Design: Population-based, cross-sectional study. Participants: One thousand sixty Chinese participants recruited from the Singapore Chinese Eye Study. Methods: All subjects underwent AS optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA). Customized software (Zhongshan Angle Assessment Program, Guangzhou, China) was used to measure the AS-OCT parameters. Anterior chamber depth was determined using IOLMaster (Carl Zeiss Meditec). Univariate and multivariate regression analyses were performed to assess the association between ACD with ocular biometric and systemic parameters. A stepwise selection algorithm was used to identify sequentially the contribution of each independent variable. Main Outcome Measures: Anterior chamber depth and ocular biometric parameters. Results: The mean age (+/- standard deviation) of participants was 56.9 +/- 8.57 years and 50.5% were men. The mean ACD was 3.24 +/- 0.35 mm. The strongest determinants of ACD were LV (R-2 = 0.582; P<0.001) and PCAL (partial R-2 = 0.186; P<0.001). For every 10-mu m increase in LV and every 1-mm increase in PCAL, ACD changed by -0.008 mm (95% confidence interval [CI], -0.009 to -0.008 mm; P<0.001) and 0.525 mm (95% CI, 0.468-0.583 mm; P<0.001), respectively. The 8 most highly associated variables (including LV, PCAL, axial length, age, and iris area) explained 80.5% of the variability in ACD, but when excluding LV and PCAL, the other 6 variables explained only 3.7% of the variability in ACD. After controlling for LV and PCAL, axial length was a poor determinant of ACD (partial R-2 = 0.006), whereas lens thickness was not associated independently with ACD. Conclusions: Lens vault and PCAL explained 76.8% of the variability in ACD. When information about LV and PCAL were available, axial length was a poor determinant of ACD, whereas lens thickness was not associated independently with ACD. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2012;119:1143-1150 (C) 2012 by the American Academy of Ophthalmology.