Ganglion Cell Complex: The Optimal Macular Outcome Measure for Detection of Glaucoma Progression across The Glaucoma Severity Spectrum

Abstract

Purpose : To demonstrate that ganglion cell complex is the optimal outcome for detection of structural progression regardless of glaucoma severity within a Bayesian hierarchical framework.

Methods : 8×8 superpixel arrays from longitudinal macular volume scans of 112 eyes were exported. A hierarchical Bayesian random intercept and slope (RIAS) model with random superpixel variance was fit to full macular thickness (FMT), outer retinal layers (ORL), ganglion cell complex (GCC), ganglion cell/inner plexiform layer (GCIPL), and ganglion cell layer (GCL) measurements for each superpixel. We estimated population and individual superpixel slopes and intercepts. The primary outcome measure was the proportion of significant negative (worsening) and positive (improving) slopes at superpixels defined as slopes with p<0.1. We compared subgroups of superpixels with mild and severe damage based on the total deviation (TD) of corresponding 10° visual field locations (TD>–8 and <–8 dB, respectively).

Results : Mean (SD) follow-up time and baseline 10° visual field mean deviation were 3.6 (0.4) years and –8.7 (5.8) dB, respectively. Thicker baseline measurements were associated with faster rates. A higher proportion of negative slopes was observed for FMT (54.9%), followed by GCC (36.5%), ORL (35.6%), GCIPL (30.6%), and GCL (19.8%) (Figure 1); the proportion of significant positive rates was small and comparable among various measures (Table 1). Out of 925 superpixels detected as progressing by only FMT, 79% also demonstrated significant ORL slopes. The proportion of significant negative rates was lower in the severe group for all inner macular measures; GCC identified the highest proportion of negative slopes among inner macular measures regardless of severity.

Conclusions : GCC is the optimal macular outcome measure for detection of change across the macula at all stages of glaucoma. The higher proportion of negative slopes for FMT is substantially explained by observed rates of ORL change.

This is a 2021 ARVO Annual Meeting abstract.

 

Figure 1. Proportion of significant negative slopes for FMT, ORL, GCC, GCIPL and GCL within the central 36 superpixels of the Spectralis’ macular grid. Numbers above each graph display superpixel location on the original 8×8 grid.

 

Table 1. Proportion of superpixels with significant negative and positive macular slopes during follow-up broken down by severity.