Comparing optical coherence tomography radial and cube scan patterns for measuring Bruch's membrane opening minimum rim width (BMO-MRW) in glaucoma and healthy eyes: cross-sectional and longitudinal analysis

Aim To compare the cube and radial scan patterns of the spectral domain optical coherence tomography (SD-OCT) for quantifying the Bruch's membrane opening minimum rim width (BMO-MRW). Methods Sixty healthy eyes and 189 glaucomatous eyes were included. The optic nerve head cube and radial pattern scans were acquired using Spectralis SD-OCT. BMO-MRWs were automatically delineated using the San Diego Automated Layer Segmentation Algorithm. The BMO-MRW diagnostic accuracy for glaucoma detection and rates of change derived from the two scan patterns were compared. Results There was a significant difference between the baseline global BMO-MRW measurements of cube and radial scans for healthy (301.957.8 mu m and 334.7 +/- 61.8 mu m, respectively, p<0.003) and glaucoma eyes (181.2 +/- 63.0 mu m and 210.2 +/- 67.2 mu m, respectively, p<0.001). The area under the receiver operating characteristic curve for differentiating between healthy and glaucoma eyes was 0.90 for both the radial scan-based and cube scan-based BMO-MRW. No significant difference in the rate of BMO-MRW change (mean follow-up years) by scan pattern was found among both healthy (cube: -1.47 mu m/year, radial: -1.53 mu m/year; p=0.48) (1.6 years) and glaucoma eyes (cube: -2.37 mu m/year, radial: -2.28 mu m/year; p=0.45) (2.6 years). Conclusion Although the cube scan-based BMO-MRW was significantly smaller than the radial scan-based BMO-MRW, we found no significant difference between the two scan patterns for detecting glaucoma, identifying BMO location and measuring the rate of BMO-MRW change. These results suggest that although BMO-MRW estimates are not interchangeable, both scan patterns can be used for monitoring BMO-MRW changes over time.