Abstract
Purpose :
To develop a method for relating regions of the optical coherence tomography (OCT) circumpapillary retinal nerve fiber layer (cpRNFL) to regions of the RNFL and retinal ganglion cell layer (RGC) probability maps.
Methods :
Based upon OCT circle and cube scans, centered on the disc and macula, a method was developed for comparing abnormal and/or progressing regions (cpROI) of the cpRNFL to abnormal regions (arcROI) seen on RNFL and RGC probability maps. With this method, the cpROI is manually marked on the cpRNFL plot (Fig. 1A), and the region of predicted abnormality is shown on the OCT probability maps (Fig. 1B & 1C) as the region with the arcuate curves. This predicted region was based upon a modified version of the Jansonius et al. model [1] for retinal nerve fiber bundle trajectories. To test the model, we used 38 eyes from 36 early glaucoma (EG) patients; all eyes were identified as progressors by 4 experts after evaluating all OCT and 10-2 and 24-2 visual field (VF) information. To obtain a cpROI for each eye, a glaucoma specialist marked the cpRNFL region of interest (cpROI) that appeared either abnormal and/or to progress over time (Fig. 1A). The predicted region (arcROI) was compared to the abnormal regions on the probability maps (Fig. 1B & 1C).
Results :
The abnormal OCT region fell within the arcROI for both the RNFL (Fig. 1B) and RGC (Fig. 1C) probability maps for 31 of the 38 eyes, for only the RNFL probability map in 1 additional eye, and for only the RGC probability map in 1 additional eye. There was a tendency, however, for the abnormal region of the RGC probability maps to extend further towards fixation than the arcROI (Fig. 1C); this occurred in 14 of the 32 successful cases. Finally, 2 eyes had abnormal regions significantly outside of the arcROI, which may have resulted from an improperly centered disc on the probability maps. For the 4 remaining eyes, the abnormal and/or progressing cpROI was subtle and within the green region of the RNFL and RGC probability maps.
Conclusions :
The method based upon the Jansonius et al. model performed well in predicting the abnormal regions on the RNFL and RGC probability maps based upon the abnormal and/or progressing region on the cpRNFL thickness plot. This method can be useful in making comparisons among the OCT thickness and probability maps, and VF points (Fig. 1). 1. Jansonius et al, Exp Eye Res, 2012.
This is a 2020 ARVO Annual Meeting abstract.