Purpose: To compare the characteristics of the peripapillary choroid (PPC) between the 2 eyes of patients with unilateral treatment-naïve normal-tension glaucoma (NTG).

Design: Observational case series. Participants: Sixty-nine patients (138 eyes) with treatment-naïve unilateral NTG.

Methods: The characteristics of PPC vasculature were evaluated by measuring PPC thickness and assessing the presence of parapapillary deep-layer microvasculature dropout (MvD). Peripapillary choroid thickness was measured by enhanced depth imaging OCT. Microvasculature dropout was assessed using OCT angiography. The area and maximum radial width of β-zone parapapillary atrophy (PPA) were measured on infrared images using the built-in caliper tool of the Spectralis OCT (Heidelberg Engineering). Main outcome measures: Between-eye differences in PPC thickness, MvD frequency, and the area and maximum width of β-zone PPA.

Results: Eyes with NTG showed higher intraocular pressure (IOP), longer axial length, thinner PPC, larger area and maximum radial width of the β-zone PPA, and more frequent MvD (P < 0.01 for each) than contralateral healthy eyes. Multivariate conditional logistic regression analysis revealed that higher IOP, thinner PPC, larger maximum radial width of β-zone PPA, and the presence of MvD were associated independently with the risk of NTG (P < 0.03 for each). In eyes with NTG, MvD location and retinal nerve fiber layer defect were correlated topographically.

Conclusions: Peripapillary choroid vasculature characteristics are significantly more compromised in eyes with NTG than in contralateral healthy eyes of patients with unilateral NTG.