Comparative optical coherence tomography study of differences in scleral shape between the superonasal and superotemporal quadrants.

PURPOSE: To determine the differences in scleral shape between the superonasal and superotemporal quadrants, the sites of scleral flap creation in trabeculectomy, using anterior segment optical coherence tomography (OCT). METHODS: Thirty-four right eyes of 34 enrolled subjects without ocular disease, with the exception of cataract or ametropia, were studied. Mean patient age was 63.2 ± 15.9 (standard deviation) years (range 28-84 years). The same examiner captured all images using anterior segment swept source OCT. The mean measurements were calculated from three images captured for each eye, 60° from the horizontal line passing through the pupillary center in the superonasal and superotemporal sclera. The radius of the scleral surface curvature and the area of the convex part of the sclera between the superonasal and the superotemporal quadrants were determined using image analysis software and the paired t test. RESULTS: The radius of the scleral curvature was significantly different in the superonasal quadrant and superotemporal quadrant (34.3 ± 12.6 vs. 18.3 ± 3.6 mm, respectively; P < 0.001). The area of the convex part of the sclera was also significantly different in the superonasal and superotemporal quadrants (0.36 ± 0.1 vs. 0.57 ± 0.1 mm(2), respectively; P < 0.001). CONCLUSIONS: Anterior segment OCT analysis of the scleral shape revealed a more gradual scleral gradient in the superonasal quadrant compared with the superotemporal quadrant.