β-zone Parapapillary Atrophy and the Rate of Retinal Nerve Fiber Layer Thinning in Glaucoma

Abstract

Purpose: : To evaluate whether β-zone parapapillary atrophy (PPA) is associated with the rate of retinal nerve fiber layer (RNFL) thickness change as assessed by trend based analysis of optical coherence tomography (OCT) RNFL thickness.

Methods: : The study included 202 glaucomatous eyes which were observed for 3 or more years with serial OCTs and stereo disc photographs. Subjects were divided into two groups according to the presence (n=144) or absence of β-zone PPA (n=58) at baseline. The rates of progressive thinning in global, quadrant, and clock-hour OCT RNFL thicknesses were determined using linear regression and compared between groups. Logistic regression analysis was used to determine the factors associated with the rate of global RNFL thinning.

Results: : The mean rate for global RNFL thinning over time was -1.03±1.50 µm/year. Eyes with β-zone PPA at baseline showed a significantly faster rate of RNFL thinning than did eyes without β-zone PPA in the inferior quadrant and 7 o’clock sector (P values<0.0026). Multivariate analysis showed significant influence of the presence of β-zone PPA and the percent increase in the PPA to disc area ratio during the follow up on the rate of OCT RNFL thinning (odds ratio, 3.314; P=0.007 and odds ratio, 2.894; P=0.003, respectively).

Conclusions: : Glaucomatous eyes with β-zone PPA are at increased risk for progressive RNFL thinning.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic disc