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Purpose To compare the diagnostic capability of 3-dimensional (3D) neuroretinal rim parameters with existing 2-dimensional (2D) neuroretinal and retinal nerve fiber layer (RNFL) thickness rim parameters using spectral domain optical coherence tomography (SD-OCT) volume scans Materials and Methods Design Institutional prospective pilot study. Study population 65 subjects (35 open angle glaucoma patients, 30 normal patients). Observation procedures One eye of each subject was included. SD-OCT was used to obtain 2D retinal nerve fiber layer (RNFL) thickness values and five neuroretinal rim parameters [i.e. 3D minimum distance band (MDB) thickness, 3D Bruch’s membrane opening-minimum rim width (BMO-MRW), 3D rim volume, 2D rim area, and 2D rim thickness]. Main outcome measures Area under the receiver operating characteristic (AUROC) curve values, sensitivity, specificity. Results Comparing all 3D with all 2D parameters, 3D rim parameters (MDB, BMO-MRW, rim volume) generally had higher AUROC curve values (range 0.770–0.946) compared to 2D parameters (RNFL thickness, rim area, rim thickness; range 0.678–0.911). For global region analyses, all 3D rim parameters (BMO-MRW, rim volume, MDB) were equal to or better than 2D parameters (RNFL thickness, rim area, rim thickness; p-values from 0.023–1.0). Among the three 3D rim parameters (MDB, BMO-MRW, and rim volume), there were no significant differences in diagnostic capability (false discovery rate > 0.05 at 95% specificity). Conclusion 3D neuroretinal rim parameters (MDB, BMO-MRW, and rim volume) demonstrated better diagnostic capability for primary and secondary open angle glaucomas compared to 2D neuroretinal parameters (rim area, rim thickness). Compared to 2D RNFL thickness, 3D neuroretinal rim parameters have the same or better diagnostic capability.

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Abstract Purpose: To determine if inter-eye asymmetry of a three-dimensional neuroretinal rim parameter, the minimum distance band, is useful in differentiating normal from open-angle glaucoma eyes. Materials and Methods: This is a cross-sectional study. Both eyes of 28 normal subjects 33 glaucoma subjects were analyzed. Subjects underwent spectral domain optical coherence tomography imaging of both eyes. A custom-designed segmentation algorithm calculated mean minimum distance band neuroretinal rim thickness globally, for four quadrants and for four sectors. Inter-eye minimum distance band thickness asymmetry was calculated as the absolute difference in minimum distance band thickness values between the right and left eyes. Results:  Increasing minimum distance band thickness asymmetry was not associated with increasing age or increasing refractive error asymmetry. Glaucoma patients had thinner mean neuroretinal rim thickness values compared to normal patients (209.0 μm versus 306.0 μm, P < 0.001). Glaucoma subjects had greater inter-eye thickness asymmetry compared to normal subjects for the global region (51.9 μm versus 17.6 μm, P < 0.001) as well as for all quadrants and all sectors. For detecting glaucoma, a thickness asymmetry value greater than 28.3 μm in the inferior quadrant yielded the greatest sum of sensitivity (87.9%) and specificity (75.0%). Globally, thickness asymmetry greater than 30.7 μm yielded the greatest sum of sensitivity (66.7%) and specificity (89.3%).  Discussion: This study indicates that inter-eye neuroretinal rim minimum distance band asymmetry measurements, using high-density spectral domain optical coherence tomography volume scans, may be an objective and quantitative tool for the evaluation of open-angle glaucoma patients.