Abstract
Purpose :
To develop retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) probability change maps (pc-map) obtained from optical coherence tomography (OCT) scans.
Methods :
The study group consisted of 70 early glaucoma or glaucoma suspect (baseline 24-2 mean deviation >-6 dB) and 29 healthy (HC)] from 99 individuals from a longitudinal, prospective study. All eyes had 24-2 and 10-2 visual fields (VFs) and baseline OCT volume scans and follow-up scans at least 1 year from the baseline date (1.8 ± 0.3 yr; range: 1.3-3.4 yr.). The OCT scans were obtained on both Topcon (12x9 mm scan) and Heidelberg (30°x25° scan) instruments. The OCT pc-map (Fig. 1, bottom rows) of the RNFL and the GCL were generated by comparing the difference in thickness (Fig. 1, top rows) between an individual eye’s baseline scan to the last follow-up against a short-term variability group (4 mos between scans), which consisted of 135 eyes (942 scans) for Topcon and 179 eyes (745 scan) for Heidelberg. A reference standard (RS) was employed to assess the diagnostic ability of these pc-maps. For the RS, we required an agreement in the region progressing based upon an evaluation of baseline and follow-up OCT and 24-2 and 10-2 VF tests. Based upon this RS, 10 eyes were classified as progressors (P). The pc-maps of the P and HC eyes were compared to identify patterns that distinguish real progression from artifacts.
Results :
For Topcon, 8 of the 10 P eyes had abnormal arcuate regions characteristic of glaucoma on both the GCL and RNFL pc-maps (arrows in[HDC1] Fig. 1). In all 8, there was clear topographic agreement between the progression seen on the RNFL and GCL pc-maps. Of the 29 HCs, 4 (14%) had damage that resembled an arcuate on the RNFL pc-map (red arrows in Fig. 2[HDC2] ). However, none of these 4 showed topographic consistent change on the GCL pc-map. Additionally, arcuates in P eyes were more temporal and curved towards fixation, while “arcuates” on HCs appeared straighter. The results for Heidelberg scans were similar. 8 out of the 10 P eyes had damage resembling an arcuate with topographic agreement on the RNFL and GCL pc-maps. Only 1 HC had arcuate-like region, and it was not confirmed on the GCL pc-maps.
Conclusions :
RNFL and GCL pc-maps for eyes with early glaucoma show topographically corresponding abnormal regions that reveals the location and extent of the region progressing.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.