Abstract
Purpose :
The impaired retinal microcirculation, microvasculature and microstructure in patients with relapsing and remitting multiple sclerosis (RRMS) are reported (Jiang et al. MSJ 2016, Jiang et al. Ophthalmology 2016). The goal was to determine the changes of these measurements in the one year follow-up.
Methods :
Seventeen RRMS patients (3 males and 14 females, age 41.5 ± 9.1 years) were imaged using retinal function imager (RFI, Optical Imaging Ltd, Rehovot , Israel), optical coherence tomography angiography (OCTA, Zeiss Angioplex, Carl Zeiss Meditec, Dublin, CA) and custom-made ultra-high resolution OCT (axial resolution ~ 3 µm) to measure retinal blood flow velocity in arterioles and venules (4.3 x 4.3 mm2), macular microvascular density (3 x 3 mm2) and thickness maps of 6 intraretinal layers (6 x 6 mm2) at baseline and follow-up visits (12.2 ± 3.6 months). Automated segmentation software (Orion, Voxeleron LLC, Pleasanton, CA) was used to segment the thickness in the annulus (1- 6 mm in diameter). For measuring microvascular network density, fractal analysis using the box counting method (Dbox representing density) was performed. The density of microvasculature in a diameter of 3 mm circle centered on the fovea was measured after removing of the large vessels (diameter ≥ 25 µm).
Results :
There were no changes in expanded disability status scale (P > 0.05) between baseline and follow-up visits. The blood flow velocities of retinal arterioles (3.14 ± 0.60 mm/s) and venules (2.48 ± 0.68 mm/s) at the follow-up were significantly lower compared to baseline (arteriole: 3.57 ± 0.61 mm/s; venule: 2.88 ± 0.56 mm/s, paired t-test: P < 0.05, n = 15). The microvascular network density (Dbox) of deep vascular plexus was 1.744 ± 0.015 at the follow-up which was lower than baseline (1.759 ± 0.015, P = 0.0002, 25 eyes of 16 patients). No significant changes were evident in superficial vascular plexus (P > 0.05). The variations of the thicknesses of all 6 segmented layers did not reach a significant level (P > 0.05, n = 17).
Conclusions :
This is the first study to follow the changes of retinal microvascular and microstrutural changes in MS. The decline of microcirculation and microvascular network density indicates that altered microvascular system could play a role in the neurodegeneration.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.