Quantitative analysis of dynamic iris changes in primary angle-closure disease with long axial lengths: the Handan Eye Study

Objective: To investigate dynamic iris changes in patients with primary angle-closure disease (PACD) with long axial length (AL) compared to those with short and medium AL. Methods: This observational cross-sectional study enrolled participants aged 35 years or older from the Handan Eye Study follow-up examination who were diagnosed with PACD and underwent Visante anterior segment optical coherence tomography (ASOCT) imaging under light and dark conditions. The right eye of each participant was included in the analysis. AL was categorized as short (<22.0 mm), medium (≥22.0 to ≤23.5 mm), or long (>23.5 mm). Anterior segment parameters, including iris dynamic changes, were compared among the three groups with different ALs. Results: Data from 448 patients with PACD were analyzed. We found that 10.9% of included eyes had a long AL with a flatter cornea; larger central anterior chamber depth, angle opening distance, anterior chamber width, anterior chamber area, and volume; and smaller lens thickness and lens vault (LV) (P< 0.05) than those with short AL. No significant difference existed between the three groups in iris thickness, iris cross-sectional area (IA), iris curvature, or pupil diameter (PD) change between light and dark (P> 0.05). The significant associated factors for IA changes were area recess area (ARA) in the dark, LV in the dark, and PD change from light to dark (P< 0.05). Conclusions: Dynamic and static iris parameters were consistent across patients with PACD with short, medium, or long AL and may contribute to the pathogenesis of angle closure in atypical PACD.