Glaucoma Severity and Progression in Individuals with Asymmetric β-zone Parapapillary Atrophy: An Intra-patient...

To investigate inter-eye differences in glaucoma severity and progression in patients with asymmetric baseline β-zone parapapillary atrophy (PPA) morphology.

Retrospective, intra-patient comparative study.

Sixty-four eyes of 32 patients with bilateral primary open-angle glaucoma and asymmetric β-zone PPA morphology.

Baseline β-zone PPA was quantitatively assessed using optic disc photographs. Each eye was classified according to angular extent as either Crescent type (<180°) or Solar-eclipse type (≥180°), and according to radial extent as either Short-extent type or Long-extent type. Glaucoma progression was evaluated using linear mixed-effects models with random intercepts and random slopes at both the patient and eye-within-patient levels.

Rates of change in visual field mean deviation (MD), visual field index (VFI), and retinal nerve fiber layer (RNFL) thickness.

The mean age was 53.2 ± 15.6 years, and the mean follow-up duration was 11.4 ± 3.2 years. Eyes with the Solar-eclipse type demonstrated significantly faster functional progression, with greater model-estimated rates of VFI loss (-1.37 vs. -0.71 %/year; P = 0.004) and MD decline (-0.49 vs. -0.27 dB/year; P = 0.006), whereas no significant differences were observed in the rates of change in average, superior, inferior, or temporal RNFL thickness (all P ≥ 0.30). Similarly, eyes with the Long-extent type showed faster decline than those with the Short-extent type for both VFI (-1.33 vs. -0.76 %/year; P = 0.014) and MD (-0.47 vs. -0.29 dB/year; P = 0.026). In multivariable mixed-effects models, β-zone PPA angular extent was the only factor independently associated with the rate of functional progression for both MD (standardized β = -0.123; P = 0.008) and VFI (standardized β = -0.312; P = 0.022). A complementary paired inter-eye difference analysis did not reach statistical significance (all P > 0.05).

In this intra-individual analysis, eyes with greater angular extent of β-zone PPA showed faster functional progression, whereas structural progression did not differ. Although this association was not confirmed in a paired inter-eye difference analysis, these findings suggest that β-zone PPA angular extent may be a useful marker of future functional worsening in glaucoma.