Abstract
Purpose :
To investigate quantitative neuroretinal rim (NRR) characteristics in eyes with pallor and glaucomatous cupping.
Methods :
We recruited patients with unilateral optic disc pallor with non-arteritic ischemic optic neuropathy. We matched pairs of eyes by disc area in five groups: pallor affected (PL-AE), unaffected fellow eye (PL-FE), glaucoma affected (GL-AE), unaffected fellow eye (GL-FE), and control eye. For quantitative evaluation of NRR structure, three rim width parameters were measured, based on Bruch’s membrane opening (BMO) plane: minimal rim width (BMO-MRW), vertical rim width (BMO-VRW), and horizontal rim width (BMO-HRW). The ratio between BMO-HRW and BMO-VRW (HV ratio) was calculated. We compared these values between inter-eye matched, pallor-glaucoma matched, and diseased-control matched groups.
Results :
We enrolled 12 pairs of eyes. In eyes with similar disc areas, each group showed characteristic NRR dimensions. PL-AE had significantly thinner BMO-MRW, BMO-VRW, and BMO-HRW than PL-FE (all P<0.001), and thicker values than GL-AE with mean values of 136.9 um, 166.7 um, and 263.4 um versus 84.8 um, 121.5 um, and 103.8 um, respectively (P=0.004, 0.015, and <0.001). Compared with control eyes, all rim parameters except BMO-HRW of PL-AE were significantly decreased. There was relative NRR tissue preservation in the horizontal direction in PL-AE, with the HRW being 64% of the fellow eye’s value, compared with 38% in glaucoma eyes. OCT consistently showed preserved prelaminar tissue in contrast to glaucoma with distinct thinning of entire rim against cup wall.
Conclusions :
There was horizontal NRR preservation of prelaminar tissue in the pallor group compared to the glaucomatous cupping group. The prelaminar area consists largely of glia; hence, preservation of glial columns under ischemic axonal loss may explain our results. Histopathologic examination should follow for confirmation.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.