The comparison of manual vs automated disc margin delineation using spectral-domain optical coherence tomography

Abstract

To examine the impact of manual vs automated disc margin delineation on optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters using spectral-domain optical coherence tomography (SDOCT). A prospective cohort study consisting of normal, glaucoma suspect (GS) and glaucoma patients who underwent ONH and RNFL measurements using SDOCT technology (RTVue; Optovue Inc.). The retinal pigment epithelium/Bruch's membrane (RPE/BM) complex end points were automatically determined first, and were manually redefined subsequently. Analysis of variance, coefficient of variation (COV), concordance correlation coefficient (CCC), and Bland-Altman plots were used for the analyses. Ninety-nine eyes of 50 subjects (age 68±10 years) consisting of 36 glaucoma, 56 GS, and 7 normal eyes were included. The RNFL thickness measurements were similar (P>0.05) between the two methods of demarcation, except for the inferior-nasal sector (P=0.04). For the ONH measurements, the cup-to-disc (C/D) ratio and rim area showed significant differences between the two methods (P<0.001). COV/CCC values for the ONH parameters were as follows: cup area 17.6%/0.88; cup volume 7.4%/0.91; average C/D ratio 18.1%/0.78; rim area 25.3%/0.69; and rim volume 42.6%/0.71, respectively. CCC/COV values for the RNFL parameters were as follows: average 2.1%/0.98; inferior-temporal quadrant 8.1%/0.79; inferior-nasal quadrant INQ quadrant 12.6%/0.67; SNQ quadrant 7.8%/0.83; and STQ quadrant 7.8%/0.88, respectively. An overall high agreement and moderate-substantial concordance was observed between the demarcation methods. Automated disc margin delineation of SDOCT can be used reliably in clinical practice.