Early Glaucoma Involves Both Deep Local, and Shallow Widespread, Retinal Nerve Fiber Damage of the Macular Region

Abstract

To better understand the nature of early glaucomatous damage of the macula by comparing the results from 10-2 visual fields, optical coherence tomography (OCT) macular cube scans, and OCT circumpapillary circle scans. One eye of each of 66 glaucoma patients or suspects, with a mean deviation (MD) on the 24-2 visual field (VF) test of better than -6 decibels (dB), was prospectively tested with 10-2 VFs and OCT macular cube and circumpapillary circle scans. Thickness and probability maps of the retinal ganglion cell plus inner plexiform (RGC+) layers were generated. A hemifield was considered abnormal if both the macular RGC+ and the 10-2 probability plots were abnormal (cluster criteria). The thickness plots of the circumpapillary retinal nerve fiber layer (RNFL) were analyzed in the context of a model that predicted the region of the disc associated with macular damage. Twenty-seven hemifields (20 eyes) had abnormal 10-2 and RGC+ probability plots: 7 in upper VF/inferior retina, 6 in lower VF/superior retina, and 7 in both hemifields. Both shallow widespread and deep local thinning of the circumpapillary RNFL were observed. The local defects were more common and closer to fixation in the upper VF/inferior retina as predicted. A model of glaucomatous damage of the macula predicted the location of both the widespread and local defects in the temporal and inferior disc quadrants. Optical coherence tomography scans of the circumpapillary RNFL and the macular RGC+ layer can aid in the identification of these defects and help in the interpretation of 24-2 and 10-2 VF tests.