Abstract
Introduction γ-Zone parapapillary atrophy (PPA), an associated feature in myopic tilted optic disc, is considered to be relevant with glaucomatous optic nerve damage in myopic eyes. This study determines the topographic relationship of γ-zone PPA with a retinal nerve fiber layer defect. Purpose To determine the topographic relationship of γ-zone PPA with a RNFL defect and to compare it with that of β-zone PPA. Design Cross-sectional, observational study. Participants. Eighty-nine eyes from 89 patients with primary open-angle glaucoma who had β-zone PPA (n = 49) or γ-zone PPA (n = 40) and a single localized RNFL defect. Methods PPA was classified according to the presence or absence of Bruch's membrane on the PPA bed in spectral-domain optical coherence tomography. The angular location of the point of maximum radial extent of PPA (PMRE) and the RNFL defect was measured with the fovea-disc axis set at 0° in color and red-free fundus photographs. Main Outcome Measures. Angular distance between the RNFL defect and the PMRE. Results There was no significant intergroup difference in the extent of the RNFL defect (P=0.920). The angular distance between the RNFL defect and the PMRE was significantly greater in γ-zone than β-zone PPA (26.49 ± 17.27° vs. 60.31 ± 17.12°, P < 0.001). The angular location of the PMRE was significantly correlated with the location of the RNFL defect in the β-zone group (r = 0.822, P < 0.001) but not in the γ-zone group. The RNFL defect was mostly located near the edge of γ-zone PPA in the γ-zone group (10.56 ± 9.47°). Conclusions An RNFL defect was observed near the edge of PPA in eyes with γ-zone PPA, in contrast to it being close to the PMRE in eyes with β-zone PPA.
Highlights
Parapapillary atrophy (PPA) has been classified into peripheral α-zone and central β-zone
Baseline Characteristics. is study initially involved 259 eyes of 259 primary open-angle glaucoma (POAG) patients who were enrolled in the Investigating Glaucoma Progression Study (IGPS) and had a single localized RNFL defect
We have evaluated the topographic relationship of the RNFL defect with the PMRE in POAG eyes with β-zone and c-zone PPA. e location of the RNFL defect was significantly correlated with the PMRE in eyes with β-zone PPA, which is consistent with a previous report [7]
Summary
Parapapillary atrophy (PPA) has been classified into peripheral α-zone and central β-zone. Studies have shown that β-zone PPA is a risk factor for the development [1] and progression [2, 3] of glaucoma. Based on the findings of both histologic and angiographic studies, vascular compromise has been proposed as being responsible for the association of PPA with glaucoma. Recent studies have further classified β-zone PPA based on the existence of Bruch’s membrane (BM) on PPA bed [4]. Ese findings suggest that PPA with BM is an age-related atrophic change, while PPA without BM is derived from scleral stretching arising from the axial elongation of the eyeball. Jonas et al [6] named PPA without BM as c-zone PPA
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