Evaluation of meridional scans for angle closure assessment with anterior segment swept-source optical coherence tomography

Background/aims As swept-source optical coherence tomography (SS-OCT) simultaneously obtains 128 meridional scans, it is important to identify which scans are playing the main role in classifying gonioscopic angle closure to simplify the analysis. We aimed to evaluate the diagnostic performance of every meridional scan in its ability to detect gonioscopic angle closure. Methods Observational study with 2027 phakic subjects consecutively recruited from a community polyclinic. Gonioscopy and SS-OCT were performed. Gonioscopic angle closure was defined as non-visibility of the posterior trabecular meshwork in >= 180 degrees of the angle, while SS-OCT was defined as iridotrabecular contact anterior to the scleral spur. The area under the receiver operating characteristic curve (AUC) was calculated to assess the diagnostic performance of each single scan, the sequential anticlockwise cumulative effect of those single scans and different combinations of them. Results The AUCs of each scan ranged from 0.73 to 0.82. The single scan at 80 degrees-260 degrees had the highest AUC (0.82, 95% CI 0.79 to 0.84) and performed significantly better than most of the temporonasal scans (from 0 degrees to 52 degrees and from 153 degrees to 179 degrees). The superoinferior scans achieved higher AUCs compared with the temporonasal ones. When assessing the cumulative effect of adding individual scans consecutively, the peak AUC (0.80) was obtained when considering the superoinferior scans closer to 80 degrees-85 degrees, but no further positive cumulative effect was seen when adding the rest of the temporonasal scans of the circumference. Conclusions In conclusion, the single SS-OCT scan at 80 degrees-260 degrees had the highest diagnostic performance. Our study suggests that the 360 degrees evaluation may not translate to better clinical utility for detection of gonioscopic angle closure.