Novel Bruch's Membrane Opening Minimum Rim Area Equalizes Disc Size Dependency and Offers High Diagnostic Power for Glaucoma

PURPOSE. The purpose of this study was to assess the diagnostic power of the novel two-dimensional parameter Bruch's membrane opening minimal rim area (BMO-MRA) in spectral-domain optical coherence tomography (SD-OCT) for detection of glaucoma compared to minimal rim width (BMO-MRW) and retinal nerve fiber layer (RNFL) thickness in large and small optic discs. METHODS. In this case-control, cross-sectional study, 207 eyes of 207 participants, including 89 controls and 97 patients with glaucoma and 21 with ocular hypertension (OHT), with a disc size < 1.63 mm(2) or >2.43 mm(2) underwent SD-OCT, confocal laser scanning tomography (CSLT), visual field testing, and clinical examination. Bruch's membrane opening-MRA BMO-MRW, RNFL thickness of SD-OCT and disc margin rim area (DM-RA) of CSLT were evaluated and analyzed for diagnostic power to detect glaucoma. RESULTS. In healthy eyes with macrodiscs, mean BMO-MRW of 243.14 +/- 43.12 mu m was significantly smaller than BMO-MRW in microdiscs (338.97 +/- 69.39; P < 0.001). Bruch's membrane opening-MRA was comparable between disc size groups with 1.22 +/- 6 0.25 mm(2) for macrodiscs and 1.26 +/- 0.27 mm(2) for microdiscs (P = 0.51), as was RNFL thickness (82.69 +/- 15.76 lm versus 78.53 +/- 11.01 lm, respectively; P = 0.28). Perimetric mean deviation was -8.7 +/- 6.3 dB in glaucoma and -0.6 +/- 1.60 dB in OHT patients. Correlation of BMO-MRA and visual field function was rho (rho) -0.70 (P < 0.001). Diagnostic power to differentiate glaucoma patients was highest for BMO-MRA. Partial area under the curve (pAUC) for BMOMRA was 0.14 for specificity between 0.8 and 1.0, exceeding pAUCs of BMO-MRW (P < 0.001), RNFL thickness (P = 0.03), and DM-RA (P = 0.01). CONCLUSIONS. Bruch's membrane opening-based minimum rim area measurements offer advantages compared to one-dimensional parameters assessing neuroretinal rim by SD-OCT. In nonglaucomatous eyes, BMO-MRA values seem comparable for the full range of disc sizes. Bruch's membrane opening-MRA surpasses other parameters in diagnostic power for glaucoma.