Abstract
Purpose :
Changes in optic nerve head swelling due to increased intracranial pressure(Papilledema) are delayed following intracranial pressure changes in IIH. Retinal vascular changes may occur more quickly and are therefore a potential non-invasive, quantitative biomarker for Idiopathic Intracranial Hypertension (IIH). Vessel Tortuosity Index (VTI) has been found to be correlated with other IIH markers in an untreated cohort. The purpose of this study is to characterize VTI in a cohort undergoing treatment.
Methods :
VTI was measured for 4 arterioles and 4 venules in a region of interest 4.5-6.4mm centered on the optic nerve. Custom software was used on retinal photographs centered on the optic nerve of eyes in subjects who completed IIHTT follow-up at study endpoint [6 Months] (n=115 subjects). VTI was averaged for arteriole and venule vessel type for each subject and eye at study endpoint. Averaged arteriole and venule VTI (aVTI, vVTI) were compared to baseline aVTI and vVTI. Use of Pearson Correlation r-value and P-value of linear regression between VTI and biomarkers were used to determine correlation and strength of correlation. Comparison of VTI and biomarkers which were significant at study endpoint 6 month include, optic nerve disc elevation area, opening pressure of lumbar puncture, retinal nerve fiber layer, optic nerve head volume, arterial and venule diameter centered at 6.4 mm from optic nerve.
Results :
At study endpoint, overall subject average aVTI was 0.15 ± 0.05 and vVTI was 0.17±0.04 which were not significantly different from untreated baseline values. In cross sectional analysis of study endpoint data, vVTI was correlated with disc elevation area on photographs (r=0.3, p=0.0001,LR), OCT-RNFL(r=0.27,p=0.002,LR), LP opening pressure (r=0.21,p=0.028,LR) and OCT Optic Nerve Head Volume(r=0.19,p=0.025, LR). aVTI was correlated with arterial diameter(r=0.15,p=0.02,LR), and vVTI was correlated with venule diameter (r= 0.073, p=0.02, LR). All other comparisons had slopes with p>0.1.
Conclusions :
Analysis of change in arteriole and venule VTI at baseline and 6 months were not significant. Therefire VTI is not a subitable independent biomarker of IIH. However, there was significant correlation between VTI and other biomarkers of IIH at both time points.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.