Purpose: To identify the determinants of anterior chamber angle narrowing after mydriasis by quantitative assessment of the anterior chamber components using anterior segment optical coherence tomography (AS-OCT).
Methods: In this intervention study, anterior chamber angle analysis was performed using AS-OCT in patients with cataract before pharmacological pupillary dilation and 30 min afterwards. Angle narrowing was quantified by the change of angle opening distance 500 after mydriasis (ΔAOD500). Multivariate linear regression and stepwise selection regression were used to identify which parameters in AS-OCT significantly determined ΔAOD500.
Results: One hundred and two Japanese patients (age, mean ± standard deviation, 71.9 ± 11.2 years) were enrolled. Multivariate analysis indicated that smaller ΔAOD500 were significantly associated with larger lens vault (LV; P < 0.001), larger iris area (IA; P = 0.003), and posterior corneal arch distance (PCAL; P = 0.01). Stepwise linear regression analysis revealed that smaller ΔAOD500 was independently associated with larger LV (partial R (2) = 0.232, P < 0.001), larger IA (partial R (2) = 0.080, P = 0.001), and smaller PCAL (partial R (2) = 0.066, P = 0.002) before mydriasis. These three factors explained 37.7 % of the decrease in ΔAOD500.
Conclusion: Larger LV, larger IA, and smaller PCAL contribute considerably to anterior chamber angle narrowing after mydriasis in patients with cataract.