While determining retinal inter-eye correlations in blood flow velocities in healthy controls, researchers found that arteriolar and venular blood flow velocities may be reduced in eyes of patients with multiple sclerosis (MS). Because the reduction was found in eyes of MS patients both with and without optic neuritis history, they believe that global blood flow alterations may be a possible part of the disease process in that cohort.

MS eyes collectively exhibited average arteriolar blood flow velocities of 3.51±0.81mm/s and venular blood flow velocities of 2.76±0.50mm/s, lower values than in controls. In relation to visual function measurements, arteriolar blood flow velocities in eyes of MS patients with optic neuritis were significantly correlated with 2.5% low contrast letter-acuity scores. Otherwise, no significant correlations were detected in arteriolar or venular blood flow velocities in MS eyes with or without optic neuritis with 100% high-contrast, or 2.5% or 1.25% low contrast letter acuity scores.

Researchers suggest that relatively higher blood flow velocities could be physiologically relevant for visual function in patients with MS but require further exploration and validation. They also conclude that the claim that microvascular alterations in the MS disease process may be widespread also requires further investigation and definitive confirmation. 

Wang L, Kwakyi O, Nguyen J, et al. Microvascular blood flow velocities measured with a retinal function imager: inter-eye correlations in healthy controls and an exploration in multiple sclerosis. Eye Vis (Lond). November 2, 2018. [Epub ahead of print].