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David Buickians, Deena Dahshan, Mahnaz Shahidi, Amir Nankali, Steven E Feldon, Heather Moss; Retinal Vessel Tortuosity Indices (VTIs) as a potential biomarker of idiopathic intracranial hypertension(IIH): Baseline analysis of the IIH treatment trial. Invest. Ophthalmol. Vis. Sci. 2022;63(7):129 – A0291.
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Changes in optic nerve head swelling (papilledema) are delayed following intracranial pressure (ICP) changes in IIH. Retinal vascular changes may occur more quickly and are therefore a potential non-invasive, quantitative biomarker for ICP changes in IIH. The purpose of this study is to characterize retinal vessel tortuosity in a cohort of untreated IIH subjects.
Peripapillary arteriolar and venular tortuosity indices (aVTI, vVTI) were measured for 4 arterioles and 4 venules in a region of interest 4.5-6.4mm centered on the optic nerve on retinal photographs centered on the optic nerve from the baseline visit (prior to treatment) of study eyes in subjects who completed IIHTT follow up (n=126). VTI was measured using custom software that uses a clustering algorithm to identify center lines of each selected vessel. Curve magnitudes were then calculated by the ratio of vessel segment length to straight length between inflection points which establish a dimensionless VTI. For each subject, VTI was averaged for each vessel type and compared with other baseline parameters from the IIHTT (demographics, IOP, ICP, BP, other photographic parameters) using Pearson correlation and linear regression(LR).
VTI measurements for ≥3 arterioles and/or venules were successful for 101 eyes. aVTI was 0.14 +/- 0.05 and vVTI was 0.12 +/ -0.07. vVTI was associated with gender(r=0.23,p= 0.02 LR), IOP(r=0.28,p=0.005 LR), ICP(r=0.17,p=0.08 LR), optic nerve elevation area(r=0.18,p=0.087 LR) and average venule diameter(r=0.27,p=0.006 LR). aVTI was associated with average arteriole diameter(r=0.19,p=0.06 LR). All other comparisons had slopes with p>0.1.
vVTI and aVTI could be measured on the majority of photographs of untreated papilledema. Cross sectional analysis showed weak correlations with other markers of IIH and local pressures. Analysis of association between VTI change and IIH treatment response are needed to assess the potential of retinal VTI as a marker of disease treatment. IIHTT Clinical Trial NCT01003639
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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