Biometric Factors Associated With Acute Primary Angle Closure: Comparison of the Affected and Fellow Eye.

Purpose: To compare ocular biometric and anterior segment parameters between the affected and fellow eye in subjects with acute primary angle closure (APAC).

Methods: We evaluated 76 subjects with unilateral APAC who had undergone bilateral laser peripheral iridotomy before enrollment. Imaging was done using anterior segment optical coherence tomography and a customized software was used to measure the following: angle opening distance (AOD750); trabecular-iris space area (TISA750); iris thickness (IT750); iris curvature (ICURV); iris area (IAREA); anterior chamber depth; area and volume (ACD; ACA and ACV); anterior chamber width (ACW); anterior vault (ACD+LV); lens vault (LV); and pupil diameter (PD). We used A-scan ultrasonography to measure axial length (AL) and lens thickness (LT). Mean differences in ocular biometric and anterior segment parameters were assessed using linear mixed model adjusting for PD.

Results: A total of 53 subjects (36 females, 67.9%) with a mean age of 62.7 ± 8.1 years were analyzed after excluding 17 unanalyzable images in at least one eye. Affected eyes had shallower ACD, smaller ACA, ACV, anterior vault, TISA750, AOD750, and ICURV (all P < 0.05). Axial length, ACW, LV, LT, IAREA, and IT750 did not differ between the eyes. In the affected eyes, IT750 was significantly associated AOD750 (P < 0.05); whereas in the fellow eyes, IT750 and AL was predictive of AOD750 (all P < 0.05).

Conclusions: Eyes with previous APAC had smaller anterior segment dimensions when compared with their fellow eyes. Iris thickness was the strongest predictor of angle width in both affected and fellow eyes.