Topographic Correlation between β-Zone Parapapillary Atrophy and Retinal Nerve Fiber Layer Defect

Objective: To investigate whether a topographic correlation exists between beta-zone parapapillary atrophy (PPA) and retinal nerve fiber layer (RNFL) defect. The location and extent of the beta-zone were examined. Design: Retrospective, cross-sectional study. Participants: One hundred twenty-eight eyes from 128 consecutive patients with primary open-angle glaucoma (POAG) and a single localized RNFL defect were included. Methods: Digital optic disc photographs of the enrolled eyes were reviewed and eyes with beta-zone PPA were identified. The topographic parameters of beta-zone PPA and RNFL defect were measured on optic disc photographs and digital red-free RNFL photographs. The association between these parameters was examined statistically. Main Outcome Measures: Angular location and angular extent of beta-zone PPA and RNFL defect, angular location of point of maximum radial extent (PMRE) of beta-zone PPA, and beta-zone PPA-to-disc area ratio. Results: Eighty-two (64.1%) of the 128 eyes with a single localized RNFL defect had beta-zone PPA. Patients with beta-zone PPA were younger (by 6.6 years) than those without beta-zone PPA (P = 0.001). beta-Zone PPA was located most commonly inferotemporally (65.9%). The RNFL defect was located in the same hemifield as the beta-zone PPA in 76% of eyes and was located in the same hemifield as PMRE in 88% of eyes. The angular location of the RNFL defect showed a linear correlation with those of beta-zone PPA (r = 0.390; P < 0.001) and PMRE (r = 0.558; P < 0.001). The angular extent of RNFL defect was not correlated significantly with that of beta-zone PPA (P = 0.106), but it was associated weakly with beta-zone PPA-to-disc area ratio (r = 0.197; P = 0.026). The angular extent of the RNFL defect also was correlated with the cup-to-disc ratio (r = 0.322; P < 0.001) and the cup-to-disc area ratio (r = 0.337; P = 0.002). Conclusions: In POAG, a localized RNFL defect is correlated spatially with beta-zone PPA. Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article. Ophthalmology 2013;120: 528-534 (C) 2013 by the American Academy of Ophthalmology.