Relationship between Minimum-Rim Width at Bruch’s Membrane Opening and Paracentral Visual Field Loss in Glaucoma

Abstract

Purpose : To identify optic nerve head (ONH) parameters strongly associated with visual field loss involving fixation in primary open angle glaucoma (POAG) and chronic angle closure glaucoma (CACG) patients.

Methods : Glaucoma patients with reliable Humphrey visual field (VF) tests and no significant retinal pathology were imaged with swept-source optical coherence tomography (OCT, Topcon). Average and minimal values of minimum-rim width at Bruch’s membrane opening (BMO-MRW) were obtained from 12 radial images centered on the ONH with an algorithm written in MATLAB and manual adjustment for segmentation errors. Average and minimal values of retinal nerve fiber layer thickness (RNFLT) were acquired using spectral domain OCT (Spectralis) from a 3.45-mm circle centered on the ONH. VF loss involving fixation was quantified by averaging the pattern deviation (PD) values at the central four locations (C4) on the Humphrey VF 24-2. One eye per patient was included. Pearson correlation was performed between structural parameters and central VF loss.

Results : Forty-three patients with POAG and 20 patients with CACG were well matched by age, gender, ethnicity and IOP on the day of imaging (mean age 66.8±10.0 years, 42.9% male, 88.9% white, 14.1±2.7 mmHg overall, Table). POAG group had better VF mean deviation (-4.6±5.2dB) than CACG (-7.9±6.5, p=0.04) but similar mean PD values at C4 (-2.9±7.0dB overall). Minimal BMO-MRW correlated significantly with PD at C4 overall (p=0.02) and in POAG (p=0.01), but not in CACG (p=0.42) (Figure). The association between minimal BMO-MRW and PD at C4 in POAG patients was further assessed with multiple regression analysis; the correlation remained significant (p=0.01) after adjusting for age (p=0.17), gender (p=0.35) and VF mean deviation (p=0.83). No significant correlation was found between PD at C4 and average BMO-MRW or average RNFLT, while the correlation with minimal RNFLT reached borderline significance in the overall group (p=0.05).

Conclusions : Minimal BMO-MRW quantifies focal damage of the neuroretinal rim within the ONH and may represent a structural biomarker for paracentral visual field loss in primary open angle glaucoma.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.