Rate of Change in Bruch's Membrane Opening-Minimum Rim Width and Peripapillary RNFL in Early Normal Tension Glaucoma

Abstract

Background: to investigate the rate of change (ROC) of Bruch's membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness in early normal tension glaucoma (NTG) patients. Methods: in this longitudinal cohort study, 115 subjects (115 eyes) diagnosed as early NTG (mean deviation > -6.0 dB) and who had completed more than five times of spectral-domain optical coherence tomography (OCT) tests with acceptable quality were included. Measurement of BMO-MRW and RNFL were performed at 3-month intervals by OCT. Linear mixed-effects model was employed to calculate the ROC in global region and six Garway-Heath sectors with adjusting age, sex, and BMO area. Results: Average follow-up was 20.99 +/- 6.99 months with OCT number of 7.54 +/- 2.12. Baseline intraocular pressure was 14.72 +/- 2.70 mmHg and MD was -2.73 +/- 2.26 dB. ROC of global BMO-MRW was -2.06 +/- 0.65 mu m/yr and RNFL was -0.96 +/- 0.16 mu m/yr (p= 0.098). The most rapid ROC was in inferotemporal sector (BMO-MRW: -3.02 +/- 0.88 mu m/yr, RNFL: -1.96 +/- 0.36 mu m/yr) followed by superotemporal sector. Conclusion: The ROC of BMO-MRW, the new parameter along with that of RNFL should be considered in the management of early NTG. BMO-MRW may show visible reduction ROC better than RNFL to detect early progression in early NTG when visual field may not show significant change.