Factors associated with anterior chamber narrowing with age: an optical coherence tomography study.

PURPOSE: The purpose of our study is to evaluate the effect of age on various anterior segment (AS) parameters in healthy eyes using AS optical coherence tomography (OCT), and to examine their relationship to anterior chamber angle (ACA) narrowing with age. METHODS: A total of 388 consecutive Korean subjects aged 30 to 89 years was imaged by AS OCT. Anterior chamber depth (ACD), iris cross-sectional area (IA), iris thickness at 750 and 1500 µ from the scleral spur (IT(750, 1500)), iris curvature (IC), lens vault (LV), and anterior chamber area (AA) were determined using Image J software (version 1.44). The absolute and normalized slopes of these parameters, adjusted for axial length and sex, were determined by linear mixed-effects modeling. Multivariate regression analysis was performed to evaluate factors associated with ACA narrowing, which was defined as the angle-opening distance (AOD(500)) at the temporal angle. RESULTS: ACD and AA had significantly negative slopes (-0.0119 mm/year, -0.0845 mm(2)/year, P < 0.0001, <0.0001) with age, and LV, IC, IT(750), IT(1500), and IA had significantly positive slopes (0.0084 mm/year, 0.0019 mm/year, 0.0006 mm/year, 0.0008 mm/year, 0.0131 mm(2)/year, all P < 0.05). IC, ACD, LV, and AA underwent the greatest changes when analyzed by normalized slopes. IC, LV, age, and axial length were associated significantly with ACA narrowing (all P < 0.0001). CONCLUSIONS: Increments of LV, IC, IT, and IA with age led to a reduction in the dimensions of the AC and to narrowing of the ACA. This may explain why aging is a significant risk factor for primary angle closure glaucoma.