Larger Beta-Zone Parapapillary Atrophy Area Is Associated With More Rapid Visual Field Progression

Abstract

Purpose: : The beta-zone of parapapillary atrophy (β-PPA) represents an area of absolute scotoma and is a prominent clinical feature of glaucoma. We evaluated whether baseline β-PPA area (mm²) is associated with more rapid visual field (VF) loss and which β-PPA parameter would best describe this relationship.

Methods: : Treated glaucoma patients (glaucomatous optic neuropathy and repeatable VF loss) with unilateral or bilateral β-PPA and ≥10 SITA-Standard 24-2 VFs in either eye from 1998-2008 were identified. Eyes with optic disc photographs, HRT imaging, <6 D myopia and at least 5 VFs following the HRT were studied. β-PPA was defined as a region of chorioretinal atrophy with visible sclera and choroidal vessels adjacent to the optic disc. The contour of the β-PPA and optic nerve were marked on the HRT image by an observer masked to the VF data using disc photos as a reference. Baseline ocular parameters (below) and patient demographics were evaluated. Rates of VF progression were determined by pointwise linear regression (Progressor®) and univariate and multivariate analyses were performed.

Results: : We enrolled 109 eyes (109 patients; mean age, 71.2±13.0 yrs). Mean number of VFs after baseline HRT was 9.7±2.7, spanning 4.9±1.3 yrs. Mean values were: baseline IOP, 17.5±4.6 mmHg; CCT 538±40 um; VF mean deviation, -4.9±3.5 db; disc area, 1.95±0.53 mm²; β-PPA area, 0.95±0.72 mm²; β-PPA area/DA ratio, 0.52±0.45; rim area 1.06±0.44 mm² and rim area/disc area ratio, 0.56±0.22. The mean rate of VF progression was 0.60±0.64 dB/yr. In the univariate model, baseline IOP (r= 0.20, p<0.01), β-PPA area (r=0.53, p<0.01) and β-PPA area/DA ratio (r=0.70, p<0.01) were associated with faster rate of progression. In the final multivariate model, baseline IOP (r=0.19, p<0.01) and β-PPA area/DA ratio (r=0.66, p<0.01) remained significant.

Conclusions: : In treated glaucoma patients, a larger baseline β-PPA area/DA ratio is associated with faster rate of VF loss.

Keywords: optic nerve • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • clinical (human) or epidemiologic studies: risk factor assessment