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Sami W. Kabbara, Linda M Zangwill, Rusdeep S Mundae, Christopher Bowd, Felipe A Medeiros, Robert N Weinreb, Akram Belghith; Bruch’s membrane opening can be assessed using both Spectralis Radial and Cube Scan Patterns. Invest. Ophthalmol. Vis. Sci. 2016;57(12):842.
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© ARVO (1962-2015); The Authors (2016-present)
Minimum rim width (BMO-MRW) is usually based on assessment of the BMO from radial ONH scans. In this study we compare the radial and cube ONH scan patterns in identifying the BMO, estimating the BMO-MRW and its rate of change, and differentiating between healthy and glaucoma eyes.
Sixty healthy eyes and 189 glaucoma eyes from the Diagnostic Innovation in Glaucoma study (DIGS) were included. BMO location and BMO-MRW were automatically delineated using the San Diego Automated Layer Segmentation Algorithm (SALSA) on Spectralis B-scans of ONH cube and radial scans. The BMO location, BMO-MRW and BMO-MRW rates of change derived from the two scan settings were compared using the mixed effect model both on a global and sectoral level. Receiver operating characteristic (ROC) curves were used to compare the diagnostic accuracy of the two scan patterns.
The average differences in BMO location between cube and radial scans in healthy and glaucoma eyes were 2.2 (SD=2.0) and 2.14 voxels (SD=1.33), respectively. There was a significant difference between the baseline mean cube and radial scan BMO-MRW for global measurement of healthy (301.9 ±57.8 µm and 334.7 ±61.8 µm, respectively p<0.003) and glaucoma group (181.2 ±63.0 µm and 210.2 ±67.2 µm, respectively P<0.0001) (Table). The area under the ROC curve (AUC) for differentiating between healthy and glaucoma eyes was 0.91 for RNFL thickness and 0.90 for both the radial and cube scan based BMO-MRW, after adjusting for disc size, age and axial length. Cube and radial scan showed no statistical difference in the BMO-MRW rate of change (mean follow-up years) among both healthy (cube: -1.47 µm /yr and radial: -1.53 µm /yr, respectively P=0.48) (1.6 years) and glaucoma eyes (cube: -2.37 µm /yr and radial: -2.28 µm /yr, respectively P=0.45) (2.6 years). Both cube and radial scan based BMO-MRW average rates of change were significantly faster in glaucoma eyes compared to healthy eyes.
Although the cube scan based BMO-MRW was significantly smaller than the radial scan based BMO-MRW, we found no significant difference between cube and radial scans for detecting glaucoma, identifying BMO location, or measuring BMO-MRW rate of change. These results suggest that the ONH cube scan as well as the radial scan can be used for monitoring glaucoma.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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