Comparison of Ganglion Cell Layer and Inner Plexiform Layer Rates of Change in Suspected and Established Glaucoma

center dot PURPOSE: We compared ganglion cell layer (GCL) and inner plexiform layer (IPL) rates of change (RoC) in pa-tients with glaucoma suspect (GS) and established glau-coma (EG) to test the hypothesis that IPL thickness changes would occur earlier than GCL changes in eyes with early damage.center dot DESIGN: Prospective, cohort study.center dot METHODS: A total of 64 GS eyes (46 patients) and 112 EG eyes (112 patients) with >2 years of follow-up and >3 macular optical coherence tomography scans were in-cluded. GCL and IPL superpixel thickness measurements were exported. A Bayesian hierarchical model with ran-dom intercepts/slopes and random residual variances was fitted to estimate RoC in individual superpixels. Normal-ized RoC and proportions of superpixels with significantly negative and positive GCL and IPL RoC were compared within the groups.center dot RESULTS: The average (SD) follow-up time and num-ber of scans were 3.5 (0.7) years and 4.2 (1.0), respec-tively, in the GS group and 3.6 (0.4) years and 7.3 (1.1) in the EG group. Mean (SD) normalized RoC was faster for GCL than IPL (-0.69 [0.05] vs -0.33 [0.04]) in the GS group, whereas it was faster for IPL (-0.47 [0.03] vs -0.28 [0.02]) in EG eyes. GCL RoC were significantly negative in 24 of 36 superpixels compared with 8 of 36 for IPL (P < .001) in GS eyes. In the EG group, 23 of 36 superpixels had significant negative IPL RoC compared with 13 of 36 superpixels for GCL (P = .006).center dot CONCLUSIONS: GCL thickness is more likely to demonstrate change over time compared with IPL in glaucoma suspects. There is no evidence of preferen-tial IPL thinning in eyes with suspected early glau-coma damage. (Am J Ophthalmol 2023;249: 12-20.(c) 2022 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY NC-ND license (http://creativecommons.org/licenses/by-nc nd/4.0/) )

Automated summary

The study compared the rates of change in the ganglion cell layer (GCL) and inner plexiform layer (IPL) in glaucoma suspect (GS) and established glaucoma (EG) patients. The results showed that IPL thickness changes occurred earlier than GCL changes in eyes with early damage. Therefore, GCL thickness is more likely to demonstrate change over time compared with IPL in glaucoma suspects.