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Editors Selection IGR 22-2

Clinical Examination Methods: Diagnostic Accuracy of AS-OCT

Comment by Tracy Z. Lang & Benjamin Xu on:

112993 Anterior Segment Optical Coherence Tomography for Detection of Narrow Angles: A Community-Based Diagnostic Accuracy Study, Pradhan S; Sah RK; Sah RK; Bhandari G; Bhandari G et al., Ophthalmology. Glaucoma, 2023; 0:

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This study assesses the diagnostic accuracy of anterior segment OCT (AS-OCT) screening for detecting gonioscopically narrow angles. Nepalese communities from the Village-Integrated Eye Worker Trial II (VIEW II) Census were randomized to receive screening or no intervention. Residents aged ≥ 60 years in the intervention group were offered OCT, and those meeting criteria were referred for gonioscopy. Primary outcomes included the sensitivity and specificity of five AS-OCT parameters.

Among 17,656 people in the intervention group, 12,633 underwent AS-OCT testing. Among the 3,116 referred participants, 858 received gonioscopy. The 5 AS-OCT parameters had areas under the receiver operating characteristic curve (AUC) ranging from 0.85 to 0.89 for predicting gonioscopically narrow angles. The angle opening distance at 750 μm from the scleral spur (AOD750) provided the most diagnostic information with an optimal sensitivity of 87% and specificity of 77%. This is consistent with previous studies highlighting AOD750 as a key predictor of gonioscopically narrow angles.

This study is well-designed and executed, with confounding and biases mitigated through community randomization. Although most referred participants did not receive gonioscopy, the AS-OCT parameter distributions were similar in the overall and gonioscopy populations, enhancing validity. However, the specificity observed may be too low to support these AS-OCT thresholds in screening, especially since the clinical benefit of treating narrow angles in the absence of elevated IOP or glaucomatous damage is unclear.^1,2 There may also be limited generalizability due to potential racial/ethnic differences in normative distributions. Nevertheless, this study offers valuable information and supports the inclusion of AS-OCT in the screening workflow, especially when manual gonioscopy is not feasible. While most eyes with gonioscopically narrow angles do not progress to vision-threatening disease, narrower angles on AS-OCT pose a higher risk. Therefore, additional longitudinal studies in diverse populations are needed to determine AS-OCT's utility in risk-stratifying eyes with narrow angles.

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