Association between beta peripapillary atrophy area and ocular rigidity, choroidal thickness and choroidal pulsatility in open-angle glaucoma

Abstract

Purpose : Beta peripapillary atrophy (ßPPA) has been shown to be associated with open-angle glaucoma (OAG), its severity and risk of progression. The pathophysiological mechanism leading to ßPPA development remains uncertain. Scleral stiffness is thought to be a major determining factor for strain at the optic nerve head. Hence we hypothesize that ocular rigidity (OR), an important biomechanical parameter of the eye which accounts primarily for the stiffness of the sclera, may be involved. The purpose of this study is to evaluate the relationship between OR and the extent of ßPPA in eyes with OAG.

Methods : OR was measured using an optical method developed by our group (Beaton et al., 2015; Sayah et al., 2020). Time-lapse optical coherence tomography (OCT) imaging and automated choroidal segmentation was used to measure the average submacular choroidal thickness (CT) and the pulsatile choroidal volume change (ΔCT). By deriving the pulsatile ocular volume change and measuring the pulsatile pressure change by dynamic contour tonometry, OR was estimated using Friedenwald’s equation. The total ßPPA area was quantified using the calipers provided by the Spectralis Heidelberg software. OR differences in OAG subjects with and without ßPPA, as well as correlations of OR, CT and ΔCT with ßPPA area were assessed using SPSS.

Results : Sixty-seven eyes of 63 subjects with OAG were considered in the study. No significant difference in OR was found in eyes with and without ßPPA (p=0.806). ßPPA area and OR were both correlated with ocular axial length (AL) (r_s=0.314, p=0.01 and r_s=-0.401, p=0.001 respectively), whereas ßPPA area and age were not (p=0.811). OR and ßPPA area were not significantly correlated (p=0.601), even after controlling for AL (p=0.857). ßPPA area was inversely correlated with CT (r_s=-0.392, p=0.001) and ΔCT (r_s=-0.275, p=0.024). Gamma peripapillary atrophy was significantly correlated with AL (r_s=0.369, p=0.002) and CT (r_s=-0.314, p=0.010), but not with ΔCT (p=0.146) and OR (p=0.691).

Conclusions : Interestingly, although OR and ßPPA area were both correlated with AL, OR and ßPPA area were not significantly correlated in our cohort. However, we did find an inverse correlation between ßPPA and both CT and ΔCT in eyes with OAG. This data suggests that reduced choroidal thickness and reduced choroidal pulsatility are associated with the presence of ßPPA in OAG.

This is a 2021 ARVO Annual Meeting abstract.