Longitudinal changes in optic nerve head perfusion in non-arteritic anterior ischemic optic neuropathy

Abstract

Purpose : To quantify optic nerve head (ONH) perfusion in non-arteritic anterior ischemic optic neuropathy (NAION) using Laser Speckle Flowgraphy (LSFG).

Methods : 12 eyes of 12 subjects (5 males, 7 females, age 72±14.5 years) with acute NAION were studied within 15 days of patient-reported vision loss with optical coherence tomography and LSFG. 7 patients (3 males, 4 females, age 79.1 ± 8.1 years) were followed at 1 to 2 months and at 3 to 4 months from onset of visual symptoms. 12 eyes of 12 age- and sex-matched subjects (5 males, 7 females, age 71±14.4 years) with normal ophthalmic findings served as a control group. Total perfusion (MA), microvascular perfusion (MT) and perfusion in larger retinal vessels (MV) were calculated in arbitrary units (AU) for the total ONH area. Unpaired t test was used to compare MA, MT and MV between NAION and controls. Changes in MA and in retinal nerve fiber layer thickness (RNFLT) were analysed with an ANOVA for repeated measures followed by Bonferroni post hoc test. The correlation between changes in MA and in RNFLT was tested with a generalized estimating equation.

Results : MA, MT and MV in NAION eyes were 25.5±6.6 AU, 15.5±3.8 AU and 41±8.6 AU, respectively. In healthy subjects MA and MT had values of 28.8±5.9 AU and 16.4±2.7 AU, which were not significantly different from the patient group (P= 0.21 and P= 0.51). In the control eyes MV was higher than in NAION eyes (53.6±11.8 AU, P<0.01).
MA significantly decreased over the follow up period (P<0.01). The decrease in MA was significant from baseline until 1 to 2 months (-29.9±12.1%; P<0.01), but not thereafter (P=1). RNFLT decreased over the follow up period (P<0.01). The decrease in RNFLT was statistically significant both from baseline until 1 to 2 months (-50±17%; P<0.01) and from 1 to 2 months until 3 to 4 months (-24.6±15.4%; P=0.03). MA was significantly correlated with RNFLT throughout the follow up period (β=0.049, P<0.01).

Conclusions : Eyes with NAION showed reduced perfusion in larger retinal vessels within the first 15 days from symptoms presentation. Longitudinal data showed that ONH perfusion is decreasing mostly within the first 1 to 2 months, while RNFL progressively thins over 3 to 4 months. The characterization of these perfusion-structure relationships may help understand the pathophysiology of NAION. LSFG may provide outcome measures for clinical trials of emerging therapies for NAION.

This is a 2020 ARVO Annual Meeting abstract.