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Sarah Houston, Ashwini Nandoskar, Richard Nicholas, Jeremy Chataway, John Greenwood, Adam M Dubis; Microvascular Abnormalities and Inner Retinal Thickness in Multiple Sclerosis. Invest. Ophthalmol. Vis. Sci. 2017;58(8):5118.
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© ARVO (1962-2015); The Authors (2016-present)
Multiple sclerosis (MS) is a chronic inflammatory neurodegenerative disease. Functional MRI studies have indicated altered brain perfusion patterns in MS patients, suggesting a possible dysfunction of microvascular architecture and flow. The purpose of this study was to assess in the retina, as a surrogate for the brain, the linkage between vascular and neural degeneration in relapsing-remitting (RR) and secondary progressive (SP) MS.
Six patients with RRMS and four patients with SPMS were imaged using SDOCT and a custom built adaptive optics scanning light ophthalmoscope (AOSLO) with confocal and split detection imaging capabilities. Automated retinal segmentation was achieved using the Iowa Reference Algorithms. Inner retinal (IR) thickness, defined as ILM to INL, was assessed using the ‘62 grid’ pattern. The superior and temporal grid regions were extracted to match AOSLO imaging locations. Microvascular images were graded on the presence or absence of capillary bolus formations, saccular/fusiform formations (SF) and hairpin loops.
Two subjects did not have sufficient image quality for microvascular grading so were excluded. In the remaining patients IR thickness in the superior region was similar between the RRMS and SPMS groups; 187 µm (SD: 51.1) and 174 µm (SD: 39.3) respectively. Temporal IR thickness was 156 µm (SD: 45.5) and 152 µm (SD: 24.6) respectively. Microvascular “bolus” formations were most common in the SPMS patient group (90.6% of images) compared with 87.5% from the RRMS group. When present, SF and hairpin loops appeared in conjunction with bolus formations. SF were present at 18.8% in the SPMS and at 16.7% in the RRMS groups and hairpin loops were more common in the SPMS group at 18.8% compared to 12.5% in the RRMS group. There is a significant correlation between IR thickness and bolus formation (r2 =0.42; p=0.03) but no correlation between the number of formations and retinal thickness or MS disability (EDSS score).
Our pilot data suggest that the retinal microvasculature is altered in both relapsing remitting and secondary progressive MS. The similarity in their frequency suggests that this may be an early feature of the disease. Given that capillary abnormalities have previously been seen in brain sections, whether these formations are a cause of MS related disability, or an effect of degeneration, remains an interesting question requiring further study.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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