Morphological characteristics of parapapillary atrophy and subsequent visual field progression in primary open-angle glaucoma

Background/Aims To investigate the associations between the morphological characteristics of beta-zone parapapillary atrophy (β-zone PPA) and subsequent visual field (VF) progression in eyes with primary open-angle glaucoma (POAG). Methods One hundred and twenty-one POAG eyes with β-zone PPA along with 48 normal eyes with β-zone PPA were included. β-zone PPA area was calculated based on the PPA pixel area/optic-disc pixel area ratio and the optical coherence tomography (OCT)-measured disc area. β-zone PPA margin irregularity was quantified as a function of both area (A) and perimeter (P, calculated as 1/(4πA/P²)). VF progression was defined using standard automated perimetry’s guided progression analysis software. Results Of the 121 POAG eyes, 49 (40.5%) showed VF progression during the 10.1±1.9 years of follow-up. The baseline β-zone PPA area was similar among the three groups ( Progressors , Non-progressors and Controls , p=0.995). However, the β-zone PPA irregularity index was significantly higher in the Progressors (p<0.001). The cumulative probability of VF progression was greater in the higher PPA irregularity index group (p<0.001, log-rank test). A Cox proportional hazards model showed the significant influences of optic disc haemorrhage (HR: 2.661, p=0.034) and higher baseline PPA irregularity index (HR: 1.455, p=0.007) on subsequent progression. Conclusions In POAG eyes, baseline β-zone PPA margin regularity was significantly associated with subsequent VF progression. Irregular margin of β-zone PPA might be the mark of vulnerability in the parapapillary area to further glaucomatous damage.