Retinal Vessel Architecture and Blood Flow in Multiple Sclerosis

Abstract

Purpose : Multiple Sclerosis (MS) is an inflammatory, neurodegenerative disease. FMRI has shown altered brain perfusion patterns in subjects with MS. Due to the difficulty in precisely probing microvascular function in the brain, we sought to assess retinal blood vessel architecture and flow in subjects with MS.

Methods : Four subjects with relapsing-remitting, one with secondary progressive MS and four age-matched controls were imaged using spectral domain optical coherence tomography (SDOCT- Bioptigen Envisu™), OCT angiography (OCTA- Optovue AngioVue™) and a custom built adaptive optics scanning light ophthalmoscope (AOSLO) with confocal and split detection imaging capabilities. Retinal thickness was assessed using macular SDOCT volumes. Superficial and deep vessel plexuses were observed over the central 6x6 mm region with OCTA. Blood vessels were imaged in foveal and parafoveal regions split detection AOSLO. Capillary erythrocyte velocity was measured in at least three vessels per ~1 deg region of interest at three foveal and parafoveal locations.

Results : MS subject total retinal (ILM to RPE) and inner retinal thickness (ILM to OPL) were below average but within 2SD of the mean. There were no qualitative differences in retinal vessel networks between controls and MS patients on OCTA. However, some capillaries in the MS patients appeared locally swollen, compared to other similarly sized capillaries, while other capillaries appeared to transit large boluses of content (Figure 1) when observed on AOSLO. Capillary blood flow was reduced in MS patients (185.0 µm/sec, 162.4 – 208.5 µm/sec) compared to normal controls (233.1 µm/sec, 201.2-277.8 µm/sec). The bolus formations and swollen capillaries were not observed in normal controls and became more prevalent with MS severity (EDSS score). Bolus formations transited more quickly (623.3 µm/sec) than erythrocytes in the same vessels (310.2 µm/sec).

Conclusions : Our limited data indicate that retinal capillaries may be altered in MS potentially leading to reduced retinal blood flow compared to age matched controls. The latter finding supports current hypotheses regarding observations from fMRI.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.