Relationship of Choroidal Microvasculature Dropout and Beta-Zone Parapapillary Atrophy with Visual Field Changes in Glaucoma

Abstract

Purpose : To evaluate the association between rates of choroidal microvasculature dropout (MvD) change and rates of beta-zone parapapillary atrophy (β-PPA) with visual field changes in primary open-angle glaucoma (POAG) eyes.

Methods : 76 eyes from 58 POAG patients with and without localized MvD at baseline having at least 4 visits and 2 years of follow-up with optical coherence tomography angiography (OCT-A) and OCT scans were included. Interobserver agreement in detecting the presence of β-PPA on fundus photographs vs. OCT-A en face was assessed and an interclass correlation coefficient (ICC) was calculated using an independent cross-sectional dataset of 98 POAG eyes of 74 patients. Area of β-PPA and MvD was evaluated on B-scan choroidal vessel density and OCT-A en face images during the follow-up period. Joint longitudinal mixed effects models were used to estimate the rates of change in β-PPA area or MvD area and visual field mean deviation.

Results : The ICC for interobserver reproducibility in measuring the β-PPA in digital fundus photographs and OCTA en-face (95% CI) was 0.862 (0.795, 0.908) and 0.935 (0.903, 0.956), respectively. Over a mean follow-up of 4.2 years, the mean rates of change in MvD area and β-PPA area (95% CI) were 0.039 (0.029, 0.048) mm² per year and 0.037 (0.030, 0.043) mm² per year, respectively. In multivariable models, the faster rate of visual field mean deviation change was significantly associated with the faster rates of change in MvD area enlargement but not with a change in β-PPA area enlargement (0.03 (0.02, 0.04) mm² per 1db worse, P=<0.001; 0.04 (0.03, 0.05) mm² per 1db worse, P=0.252, respectively).

Conclusions : Interobserver reproducibility showed that OCT-A en face was more reproducible in measuring β-PPA than digital fundus photographs. Furthermore, rates of MvD area, but not β-PPA area, were associated with changes of visual field loss in POAG eyes. These findings enhance the understanding of the role of MvD in glaucoma and suggest that assessment of MvD is useful for detection of patients at a high risk of faster visual field loss.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

Figure 1. Scatterplot showing the correlation between visual field loss with β-PPA enlargement and MvD area enlargement.