OCT metrics for the macular region are more sensitive for detecting glaucomatous progression than OCT circumpapillary metrics

Abstract

Purpose : To evaluate the sensitivity for detecting structural progression using optical coherence tomography (OCT) metrics and other local measurements using permutation analysis.

Methods : One-hundred and eight eyes of 108 patients with a diagnosis, or suspect, of glaucoma, from the observational Macular Progression Study (MAPS) had series of at least 6 posterior pole, circumpapillary, and radial OCT scans. The mean (and SD) number of scans per eye was 10.5 (3.7) with a mean follow up of 4.1 (1.9) years. We assessed the following OCT measures: (a) circumpapillary retinal nerve fiber layer (cpRNFL), namely, the 768 values of the cpRNFL thickness shown as the black curve in the blue panel in Fig. 1A and the 48 values of the minimum rim width (MRW) in the blue panel in Fig. 1 B, (b) macular sectors: the 6 sectoral measures of the ganglion cell layer (GCL), GCL + inner plexiform layer (IPL), and the ganglion cell complex (GCC) thickness (green panel in Fig. 1 C), and (c) macular superpixel grid: thickness of the GCL in the 8×8, 4×4 and 2×2 grids of superpixels as well as a macular-specific 6×6 grid within the red rectangle in Fig. 1 D. Progression was assessed using permutations of local or sectorial linear regression to construct a 1-tail significance test for the alternative hypothesis that there is loss occurring over time. Positive rates (PR) and false positive rates (FPR) were obtained for detection of progression. For comparison purposes, PR was also obtained for simple linear regression of the global thickness.

Results : Fig. 2 shows the PR and FPR for all metrics. At a 5% significance level (p < 0.05), the GCL macular sectors had the greatest PR at 71%, followed by the macular 6×6 superpixel grid at 69%. The rest of measurements were lower than 64%. For linear regression of all global indices, the average decrease in PR was 14%. The FPR of all methods were at about 5% as expected.

Conclusions : GCL macular sectors and GCL macular superpixel grids had greater PR for detecting progression of glaucomatous damage than cpRNFL thickness or MRW measurements. Focal and sectorial analyses have increased sensitivity with respect to global indices at the same specificity levels.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.

 

Reports of OCT metrics

 

PR and FPR of progression analysis of OCT metrics and other local measurements. The regions shadowed in blue represents the 95% confidence bands for the PR curves in solid blue