Spectral Domain Optical Coherence Tomography "Bruch’s Membrane Opening Minimum Rim Area" is More Closely Associated with Functional Status than Heidelberg Retina Tomograph Rim Area in Human Ocular Hypertension and Early Glaucoma

Abstract

Purpose: : To compare the structure-function correlation between two measures of Optic Nerve Head (ONH) rim area and visual field functional status.

Methods: : This cross-sectional analysis included 140 participants who underwent Heidelberg Retina Tomography (HRT) & Spectral Domain Optical Coherence Tomography (SDOCT; Heidelberg Spectralis, 870 nm) scanning and Humphrey automated perimetry testing (24-2 SITA Standard) on the same day. One eye per participant was chosen randomly. For each SDOCT scan, 24 high-resolution radial B-scans centered on the ONH were delineated and quantified to produce the "Bruch’s Membrane Opening Minimum Rim Area" (BMO-MRA). HRT rim area (HRT-RA) was extracted from standard HRT outputs. A random effects model was constructed to assess the association between BMO-MRA and HRT-RA and their respective associations with age-corrected visual field sensitivity loss (Mean Deviation, MD).

Results: : The mean MD was -0.61 dB (range -16.5 - 2.7), mean BMO-MRA was 1.16 mm² and mean HRT-RA was 1.52 mm². The correlation between BMO-MRA and HRT-RA was 0.50. The correlation with MD was 0.55 when using BMO-MRA and 0.33 when using HRT-RA. This difference was significant (p = 0.006; Steiger’s Z₂* statistic). When both rim area measures were combined in a mixed effects model to predict MD, the HRT-RA measure was not significant (p = 0.36).

Conclusions: : Correlation with MD is significantly better when using SDOCT BMO-MRA than when using HRT-RA. SDOCT BMO-MRA is likely to be more closely associated with functional status than ONH rim assessment strategies like HRT-RA because it represents both a more accurate border of the rim tissue by identifying structures not visible at the retinal surface and is assessed at an anatomical plane that is more likely to be perpendicular to the largest number of axons.

Keywords: perimetry • optic disc • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)