Anterior chamber depth and iridocorneal angle in healthy White subjects: effects of age, gender and refraction

Purpose: Prior to phakic intraocular lens implantation, it is important to obtain precise knowledge of the anterior chamber depth (ACD). Accurate topographic evaluation of the iridocorneal angle is helpful in estimating risk for angle-closure glaucoma. This study investigated the use of the Orbscan II system to measure ACD and the iridocorneal angle in healthy subjects and assessed the influences of age, gender and spherical equivalent on these parameters. Methods: The Orbscan II system was used to determine the ACD and iridocorneal angle in eight different positions in 390 healthy White subjects with a mean age of 41 +/- 16 years (range 10-80 years). The sample included 242 male and 148 female subjects. The influences of age, gender and spherical equivalent were assessed using multiple regression analysis. Results: Mean ACD was 2.87 +/- 0.04 mm in male subjects and 2.81 +/- 0.37 mm in female subjects. The explanatory variables relevant to the ACD were age (partial regression coefficient B = - 0.0115, p < 0.0001), spherical equivalent (B = - 0.0562, p < 0.0001) and gender (B = 0.0996, p = 0.0036). The mean iridocorneal angle (MIA) was 30.7 +/- 2.0 degrees in male and 31.6 +/- 2.1 degrees in female subjects. The variables relevant to the MIA were gender (B = - 0.865, p < 0.0001), age (B = - 0.017, p = 0.0007) and spherical equivalent (B = - 0.121, p = 0.001). The superior iridocorneal angle displayed the strongest negative correlation with age, whereas the temporal angle exhibited the least correlation with age. Conclusions: The decline in ACD appears to be linear with age, amounting to a mean of 0.58 mm over 50 years. This may become clinically relevant in the use of phakic intraocular lenses. In addition, the angle is more severely constricted in the superior quadrant than in the temporal quadrant.