Comparison of retinal nerve fiber layer thickness and Bruch’s membrane opening minimum rim width thinning rate in open-angle glaucoma

This study aimed to compare the rate of thinning between retinal nerve fiber layer thickness (RNFLT) and Bruch’s membrane opening minimum rim width (BMO-MRW) in open-angle glaucoma (OAG) according to glaucoma severity. We retrospectively reviewed subjects with a total of 111 eyes with OAG that had undergone optical coherence tomography more than four times during more than 3 years of follow-up. The subjects were divided into three groups based on the mean deviation (MD) of the baseline visual field test: high MD (MD > − 2 dB), medium MD (− 2 dB ≥ MD > − 6 dB), and low MD (− 6 dB ≥ MD > − 12 dB) groups. A linear mixed model was employed to compare the rate of thinning between RNFLT and BMO-MRW among the three groups. The rate of RNFLT thinning was fastest in the inferotemporal sector in all three groups. The rate of BMO-MRW thinning was fastest in the inferotemporal sector of the high MD group and the superotemporal sector of the other two groups. Among the three groups, the rate of RNFLT thinning was not significantly different in the global sector and all sectors except the nasal sector. The rate of BMO-MRW thinning in the inferotemporal sector showed no significant difference, but that in the superotemporal sector was faster in the medium MD and low MD groups than in the high MD group. The fastest rate of RNFLT thinning was consistently observed in the inferotemporal sector, but BMO-MRW showed a change in the fastest thinning sector from inferotemporal to superotemporal, with increasing severity in early to moderate OAG. The difference in the changes in the two parameters may help understand the pathogenesis of glaucoma and predict its progression.