Comparison of Optic Nerve Blood Flow in Multiple Sclerosis and Healthy Eyes Using Laser Speckle Contrast Imaging

Abstract

Purpose : Multiple sclerosis (MS) is an inflammatory and neurodegenerative disorder causing demyelination of the central nervous system, which often causes optic neuritis and thinning of the retinal layers. Prior work has shown altered cerebral blood flow in MS and some studies have suggested changes in ocular blood flow (OBF) of MS patients. Our study aims to compare the relationship between optic nerve head blood flow in MS versus control participants using laser speckle contrast imaging (LSCI), a novel imaging modality in the MS population.

Methods : LSCI data was obtained from fifteen participants with MS and fifteen healthy controls using a noninvasive portable OBF imager called XyCAM RI (Vasoptic Medical, Inc., Columbia, MD). A six-second video of a 25-degree field of view centered on the optic disc was captured. The optic nerve was identified using a semi-automated method and dynamic features associated with the pulsatile dynamic blood flow velocity indices (BFVi) were calculated. Specifically, we assessed the peak flow, dip flow, mean flow, volumetric rise index (VRI), volumetric fall index (VFI), and cycle-time. A generalized estimating equation was used to account for both eyes and determine the effect of MS status on OBF accounting for optic neuritis status, heart rate, and age.

Results : 45 eyes of 30 participants were imaged. There were no significant differences in age (MS: 50 ± 15 years, Control: 51 ±12) or sex between the two cohorts. Eyes of patients with MS had a mean BFVi of 8.0 +/- 2.2 arbitrary units (a.u.), which was significantly higher than control eyes 7.4 ± 1.5 a.u. (P = 0.03). Mean BFVi declined with older age (P = 0.01) and faster heart rate (P < 0.01). Similarly, BFVi values for the peak (10.4 ± 2.6 a.u. vs. 9.4 ± 1.9 a.u., P=0.05), dip (7.1 ± 2.0 a.u. vs. 9.4 ± 1.9 a.u., P=0.02), mean (8.0 ± 2.2 a.u. vs. 7.4 ± 1.5 a.u., P=0.03), VRI (2.4 ± 0.5 vs. 2.0 ± 0.4, P=0.03), and VFI (5.3 ± 1.3 vs. 4.3 +/- 0.9, P=0.04) were all greater in MS as compared to controls.

Conclusions : Optic disc blood flow velocity indices were elevated in MS eyes than control subjects. Increasing age and higher heart rate resulted in decreased BFVi. Further work and continued recruitment are necessary to confirm this finding and study the relationship of retinal blood flow with the type and stage of MS.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.