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

Aims To examine the impact of manual vs automated disc margin delineation on optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters using spectraldomain optical coherence tomography (SDOCT). Methods 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. Results 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; inferiortemporal 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. Conclusion 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.