Assessment of Change in Retinal Layers at the Macula in Glaucoma Patients and Correlation to Visual Field Index

Abstract

Purpose : To evaluate retinal structural changes at the macula in glaucoma patients, glaucoma suspects and subjects without any known ocular disease using spectral-domain OCT (SD-OCT).

Methods : A total of 58 eyes (31 subjects) were enrolled in the study. Twenty-three eyes from 12 glaucoma patients and 35 eyes from 19 glaucoma suspects (as determined by a glaucoma specialist) underwent SD-OCT (Heidelberg Spectralis®) imaging. Visual field indices (VFIs) were obtained using 24-2 Humphrey’s visual field test (SITA Standard). Heidelberg Heyex™ version 5.2 software was used to segment the horizontal B-scans passing through the fovea in 0.5 mm increments to obtain thicknesses of retinal pigment epithelium (RPE), photoreceptor layer (PR), inner nuclear layer (INL), NFL, and combined ganglion cell and NFL (GCL+NFL) layers (Figure). Thickness values from study subjects were compared to a control group of 51 eyes (51 subjects). VFI values were correlated with retinal layer thicknesses using Spearman’s rank correlation test.

Results : Mean age of glaucoma subjects, glaucoma suspects and normal subjects were 69.8 (range: 41-84), 66.3 (range: 21-91), and 52.0 (range: 40-75) years, respectively. Significant thinning was noted in the following layers in patients with glaucoma compared to normal subjects: FRT, RPE, INL, NFL and GCL+NFL. Glaucoma suspects showed significant thinning in the FRT, INL and GCL+NFL layers compared to normal subjects. Glaucomatous eyes had significant thinning in the NFL and GCL+NFL layers compared to eyes that were glaucoma suspects (Table). GCL+NFL layer thickness was positively correlated with VFI among patients with glaucoma only (ρ=0.843; p<0.001).

Conclusions : Eyes of glaucoma patients and glaucoma suspects may demonstrate thinning of several retinal layers at the macula, most significantly FRT, INL and GCL+NFL layers. The GCL+NFL layer is significantly thinner in eyes of glaucoma patients compared to glaucoma suspects. The thinning also correlates with VFI. In addition, glaucomatous eyes may also show thinning of the RPE.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Table - Mean thickness values of retinal layers along the foveal B-scan. P-values were calculated from two-tailed non-parametric Mann-Whitney U test. Statistical significance was set at p<0.05.

 

Figure - Segmented thickness values at various retinal layers.