Detection of Bruch's Membrane Opening in Healthy Individuals and Glaucoma Patients with and without High Myopia

Purpose: To determine the proportions of eyes with indiscernible Bruch's membrane opening (BMO) in glaucoma patients and healthy individuals with and without high myopia and to investigate factors contributing to indiscernible BMO.

Design: Cross-sectional study.

Participants: Five hundred eyes from 315 participants, including 212 high myopic eyes (axial length [AL], ≥26 mm) from 80 glaucoma patients and 60 healthy individuals and 288 non-high myopic eyes (AL, <26 mm) from 96 glaucoma patients and 88 healthy individuals.

Methods: The optic disc was imaged by the Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) using 24 equally spaced radial B-scans. The BMO was located independently by 2 trained observers and was recorded as discernible or indiscernible over 48 meridians in each eye. The BMO of a meridian was determined to be indiscernible when both observers failed to identify its location. The agreement between the observers was evaluated with κ statistics. Factors associated with indiscernible BMO were identified with multivariable, multilevel logistic regression modeling.

Main outcome measures: Proportions of eyes with indiscernible BMO and hazard ratios (HRs) of factors associated with indiscernible BMO.

Results: The agreement for assessment of BMO visibility between the observers was good (κ, 0.631; 95% confidence interval, 0.602-0.661). In the groups with and without high myopia, 32.1% and 8.2% of glaucomatous eyes had 1 or more meridians with indiscernible BMO, respectively. In the healthy eyes, the respective proportions were 28.0% and 3.9%. The proportions were significantly higher in eyes with high myopia compared to eyes without high myopia in the glaucoma group (P < 0.001) and the healthy group (P < 0.001). The temporal meridian, followed by the inferotemporal and superotemporal meridians, of the optic disc were the most frequent locations with indiscernible BMO. Increased AL, advanced glaucoma, β parapapillary atrophy, and young age were associated with an increased HR of indiscernible BMO (P ≤ 0.032).

Conclusions: A significant proportion of high myopic eyes have indiscernible BMO at the temporal, superotemporal, and inferotemporal meridians of the optic disc, which may compromise the measurement of neuroretinal rim in the diagnostic evaluation of glaucoma.