Lens opacity, thickness, and position in subjects with acute primary angle closure

Purpose: To compare lens thickness (LT), lens position (LP), relative lens position (RLP), and degree and type of lens opacity between affected and fellow eyes of subjects with acute primary angle closure (APAC) to identify any differences in lens characteristics that may be contributory to the acute episode. In addition, axial length (AL) and anterior chamber depth (ACD) measurements were evaluated. Methods: Seventy-three study subjects with unilateral APAC were treated with sequential laser iridotomy (LI) in both eyes. Two weeks after LL ACD, LT, and AL measurements were made in both eyes using ultrasound pachymetry. LP was defined as ACD + (2)/(LT)-L-1 and RLP as LP/AL. The Lens Opacity Classification III (LOCS III) System was used for grading lens opacity. Results: The subjects were 90% Chinese and 63% female. Mean age was 61.0 +/- 10.9 years. Significant differences between the affected and fellow eyes were found in the ACD (2.11 +/- 0.35 vs 2.18 +/- 0.23; P = 0.02) and LP (4.61 +/- 0.47 vs 4.75 +/- 0.29; P = 0.02). Cortical opacity was greater in fellow eyes (0.32 +/- 0.72 vs 0.53 +/- 0.95; P = 0.02). There was no difference in LT, RLP, or degree of lens opacity in the nuclear and posterior subcapsular regions. Conclusions: Compared with fellow eyes, APAC-affected eyes have shallower ACD, more anterior LP, and less cortical opacity. These differences may be contributory to APAC.