Functional Loss in Glaucoma Better Correlates With Ganglion Cell Layer Thinning

Functional visual loss in glaucoma correlated better with ganglion cell layer (GCL) thinning than with retinal nerve fiber layer (RNFL) thinning, according to a study presented at the Association for Research in Vision and Ophthalmology (ARVO) Annual Meeting held in New Orleans, April 23-27, 2023.

This study was designed to evaluate the correlation between 24-2 visual field (VF) parameters and the thinning of the RNFL and GCL. Investigators from Columbia University Irving Medical Center sourced data for this study from a database containing VF scans from 78,298 individuals and optical coherence tomography (OCT) scans from 49,559 individuals that were obtained in a university setting.

For this study, data from the subset of patients (N=292; n=499 eyes) who had same-day VF and OCT exams on 5 or more visits and had 5 or more years of follow-up were assessed for correlations between 24-2 VF rates of progression (ROP_24-2) and RNFL and GCL thinning.

The patients were aged mean 66 (SD, 11.3) years and had an average follow-up duration of 7.7 years and data from 6.2 visits.

At baseline, global 24-2 mean deviation was -3.9 (SD, 4.9) dB, RNFL thickness was 77.5 (SD, 12.8) mm, and GCL thickness was 69.4 (SD, 11.1) mm.

The ROP_24-2 was strongly correlated with both RNFL and GCL rates of change (both P <.001) but was more strongly correlated with the GCL rate of change (r, 0.312) than the RNFL rate of change (r, 0.197).

This trend was consistent with both the rates of changes in the inferior quadrant (GCL: r, 0.238; RNFL: r, 0.192) and superior quadrant (GCL: r, 0.264; RNFL: r, 0.217).

The potential limitations of this study included the small sample size, the retrospective design, and not performing a subgroup analysis on the basis of glaucoma severity.

“Glaucomatous visual field loss rates correlate better with the rates of GCL thinning than with the rates of RNFL thinning,” according to the researchers. “GCL thinning may be a better marker of functional loss in glaucoma than RNFL.”