Changes in Bruch's Membrane Opening-Minimum Rim Width after Reduction of Intraocular Pressure in Eyes with Open-Angle Glaucoma

Introduction: Bruch's membrane opening-minimum rim width (BMO-MRW) is measured perpendicular to the neural tissue axis and considers the variable trajectory of axons over the point of measurement, similar to the measurement strategies used for circumpapillary retinal nerve fiber layer thickness (c-RNFLT). However, changes in BMO-MRW in relation to those in c-RNFLT with intraocular pressure (IOP) reduction remain unclear. This study evaluated changes in BMO-MRW and their relationship to changes in the optic nerve head cup size and c-RNFLT in patients with open-angle glaucoma post-trabeculectomy (TLE). Methods: Thirty-one eyes of 31 patients were enrolled. All patients underwent fundus imaging with spectral domain-optical coherence tomography before and three months after TLE. We measured BMO-MRW and c-RNFLT and evaluated the cup size by calculating the cup profile area using the ImageJ program. Results: Reduction of IOP led to a significant increase in BMO-MRW and a significant decrease in cup size. Changes in the BMO-MRW of the whole disc and the temporal superior segments correlated significantly with the change in IOP. In multiple regression analysis, there was a significant relationship between the changes in cup size and axial length (but not the change in IOP) and the change in BMO-MRW. Although c-RNFLT did not increase significantly post-TLE, the mean deviation of the visual field at baseline, cup size at baseline, and change in cup size were considered to contribute to the change in c-RNFLT. Conclusions: BMO-MRW increased after adequate TLE-induced reduction of IOP. The increase in BMO-MRW was related to the cup size and reduction in axial length.