Retinal Vessel Phenotype in Patients with Non-Arteritic Anterior Ischemic Optic Neuropathy

Purpose: The pathophysiology of non-arteritic AION (N-AION) is not completely understood. Studies of the retinal vasculature phenotype in patients with N-AION could help us to understand vascular abnormalities associated with the disease.

Design: Retrospective case series with matched controls.

Methods: Study population: 57 patients with N-AION and 57 controls matched to N-AION patients for sex, age, systemic hypertension, diabetes and obstructive sleep apnea syndrome, between September 2007 and July 2017.

Main outcome measures: All patients and control subjects underwent a complete ocular examination and 45-degree funduscopic color photographs. The widths of the six largest arteries in zone B (between 0.5 and 1 optic disc diameter from the optic disc), summarized by the central retinal artery equivalent (CRAE), the widths of the six largest veins in zone B, summarized by the central retinal vein equivalent (CRVE), the arteriole-tovenule ratio (AVR), tortuosity and fractal dimension (FD) were measured on the two groups using VAMPIRE (Vessel Assessment and Measurement Platform for Images of the Retina), a software tool for efficient semi-automatic quantification of the retinal vasculature morphology in fundus camera images. Univariate analysis using the Student t-test and MacNemar Chi-squared test for paired sample and Generalized Estimated Equations for modeling the VAMPIRE parameters as dependent variables were used.

Results: CRVE and FD (D0a) were significantly higher in the N-AION group when compared with the control group, whereas the AVR and vascular tortuosity were significantly lower. In comparison with controls, acute N-AION yielded increased CRAE value (174 ±33 vs. 160 ±13 μm) while resolution N-AION yielded decreased CRAE value (152 ±12 vs. 156 ±33 μm). Acute N-AION yielded increased CRVE value (244 ±35 vs. 210 ±21 μm) while resolution N-AION yielded unchanged CRVE value. We found no difference between groups for age, refraction, optic disc diameter, CRAE, and FD.

Conclusions: Retinal vascular parameters were different in our sample between N-AION and control patients, especially at the acute stage of the disease. Our results suggest a normalization of the same parameters at the resolution stage.