Structure-Function Relationship Between the Bruch Membrane Opening-based Minimum Rim Width and Visual Field Defects in Advanced Glaucoma Serhat Imamoglu, MD,* NimetYesim Ercalik,MD,* *Haydarpasa Numune Training and Research Hospital, Istanbul,TURKEY Purpose: To investigate the relationship between the Bruch membrane opening-minimum rim width (BMO-MRW) (global and temporal) parameters with spectral-domain optical coherence tomography (SD-OCT) and visual field (VF) sensitivity on the 10-2 test in patients with advanced glaucoma. Materials and Methods: This cross-sectional, observational study included a total of 33 eyes of 29 patients. To evaluate VF sensitivity, automated white-on-white perimetry was performed using a Humphrey field analyzer. The mean deviation (MD) and pattern SD values were used to characterize the degree of functional damage. BMO-MRW and peripapillary retinal nerve fiber layer thickness were obtained with SD-OCT (Table 1). According to the Garway- Heath map and fovea and BMO axis, the 90 degrees temporal sector of the optic disc corresponding to the central VF was divided into upper and lower parts (Fig 1). Results: The upper and lower temporal BMO-MRW parameters showed stronger correlations with the MD parameters of their corresponding VFs when compared with both global and temporal MRW parameters. Global and temporal retinal nerve fiber layer thickness parameters were also correlated with global MD parameters (Table 2). Discussion: Pollet-Villard et al1studied the structure-function relationship between VF sensitivity on 24-2 test and RNFL thickness and ONH measurements using SD-OCT, including the BMO-MRW parameter in patients with glaucoma, suspected glaucoma, and healthy subjects. They reported that the relationship between BMO-MRW and retinal sensitivity seems to be much stronger than the relationship between RNFL thickness and VF sensitivity in the patients with advanced glaucoma subgroup. Furthermore, they hypothesized that there is less of a floor effect with MRW, with changes that can be detected in eyes with advanced VF loss, when compared with RNFL thickness. In this study, we found similar correlations of both BMO-MRW and RNFL thickness with VF sensitivities on the 10-2 test It was also reported that the number of axons would likely better correlate with the minimum cross-sectional area (BMO-MRA). 2As a limitation, we did not analyze the BMO-MRA parameter. Conclusions: BMO-MRW measurements in the upper and lower parts of the 90 degrees temporal sector of the optic nerve head by SD-OCT and their corresponding VF sensitivity on the 10-2 test were found highly correlated. These BMO-MRW measurements could offer a means of predicting the status of visual hemifields in patients who are unable to undergo VF testing. Further longitudinal studies with larger series evaluating BMO-MRW parameters with SD-OCT are also needed to monitor progression in advanced glaucoma. References: 1.Pollet-Villard F, Chiquet C, Romanet JP, et al. Structurefunction relationships with spectral-domain optical coherence tomography retinal nerve fiber layer and optic nerve head measurements. Invest Ophthalmol Vis Sci. 2014;55:2953–2962. 2. Gardiner SK, Ren R, Yang H, et al. A method to estimate the amount of neuroretinal rim tissue in glaucoma: comparison with current methods for measuring rim area. Am J Ophthalmol. 2014;157:540–549