IMPORTANCE Baseline anterior segment imaging parameters associated with incident gonioscopic angle closure, to our knowledge, are unknown. OBJECTIVE To identify baseline quantitative anterior segment optical coherence tomography parameters associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline. DESIGN, SETTING, AND PARTICIPANTS Three hundred forty-two participants aged 50 years or older were recruited to participate in this prospective, community-based observational study. Participants underwent gonioscopy and anterior segment optical coherence tomography imaging at baseline and after 4 years. Custom image analysis software was used to quantify anterior chamber parameters from anterior segment optical coherence tomography images. MAIN OUTCOMES AND MEASURES Baseline anterior segment optical coherence tomography measurements among participants with gonioscopically open vs closed angles at follow-up. RESULTS Of the 342 participants, 187 (55%) were women and 297 (87%) were Chinese. The response rate was 62.4%. Forty-nine participants (14.3%) developed gonioscopic angle closure after 4 years. The mean age (SD) at baseline of the 49 participants was 62.9 (8.0) years, 15 (30.6%) were men, and 43 (87.8%) were Chinese. These participants had a smaller baseline angle opening distance at 750 μm (AOD750) (0.15 mm; 95%CI, 0.12-0.18), trabecular iris surface area at 750 μm (0.07mm2; 95%CI, 0.05-0.08), anterior chamber area (30mm2; 95%CI, 2.27-3.74), and anterior chamber volume (24.32mm2; 95%CI, 18.20-30.44) (all P < .001). Baseline iris curvature (-0.08; 95%CI, -0.12 to -0.04) and lens vault (LV) measurements (-0.29 mm; 95%CI, -0.37 to -0.21) were larger among these participants ( all P < .001). A model consisting of the LV and AOD750 measurements explained 38%of the variance in gonioscopic angle closure occurring at 4 years, with LV accounting for 28%of this variance. For every 0.1mmincrease in LV and 0.1mmdecrease in AOD750, the odds of developing gonioscopic angle closure was 1.29 (95%CI, 1.07-1.57) and 3.27 (95%CI, 1.87-5.69), respectively. In terms of per SD change in LV and AOD750, this translates to an odds ratio of 2.14 (95%CI, 2.48-12.34) and 5.53 (95%CI, 1.22-3.77), respectively. A baseline LV cut-off value of >0.56mmhad 64.6%sensitivity and 84.0% specificity for identifying participants who developed angle closure. CONCLUSIONS AND RELEVANCE These findings suggest that smaller AOD750 and larger LV measurements are associated with the development of incident gonioscopic angle closure after 4 years among participants with gonioscopically open angles at baseline.
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