Differentiation of Parapapillary Atrophy Using Spectral-Domain Optical Coherence Tomography

Abstract

To develop a classification of parapapillary atrophy (PPA) based on its relationship with the location of Bruch's membrane (BM) termination in primary open-angle glaucoma (POAG) patients. Cross-sectional observational study. This study analyzed 161 eyes from 161 POAG patients who had temporal β-zone PPA, the width of which was more than 200 μm on at least 1 horizontal scan image obtained by spectral-domain optical coherence tomography within the mid horizontal one third of the optic nerve. Based on the extent of BM within the PPA area, eyes were categorized as group A (intact BM; 76 eyes), group B (discontinuous BM; 65 eyes), and group C (lacking BM; 20 eyes). Differences in the demographic, clinical, and ocular characteristics were compared using analysis of variance and chi-square tests among the 3 groups. The distance from the temporal optic disc margin to the temporal margin of the β-zone PPA (PPA width) and to the edge of the BM (width of PPA without BM [PPA-BM]) were measured on 3 horizontal scans within the mid horizontal one third of the optic nerve, and the averages of the measured values were analyzed. The configuration of the border tissue of Elschnig at the temporal disc margin was assessed. Factors and configuration of the border tissue of Elschnig associated with each PPA type. The mean age of group A was significantly higher than that of groups of B and C (P<0.001). The mean axial length was greatest in group C (group C>group B>group A; P<0.001). In group A, the border tissue mainly had a nonoblique configuration (49/76 eyes; 64.5%), whereas most of the eyes in group B (59/65 eyes; 90.8%) and all eyes in group C (20 eyes) it had an externally oblique configuration (P<0.001). A longer axial length was correlated significantly with a larger PPA-BM width (r = 0.478; P<0.001). A morphologic classification of PPA, which may reflect differing pathogenesis among the groups, is proposed. Parapapillary atrophy with intact BM may be an age-related atrophic change, whereas PPA lacking BM may result from scleral stretching associated with elongation of the globe. Proprietary or commercial disclosure may be found after the references.