Longitudinal Assessment of Quantitative Ultra-widefield Ischemic and Vascular Parameters in Sickle Cell Retinopathy: Exploratory Evaluation of the Geodesic Diameter

Abstract

Purpose : To evaluate longitudinal ischemic and vasculature parameters, including ischemic index, vessel area, length and geodesic diameter (GD) in sickle cell retinopathy on ultra-widefield fluorescein angiography (UWFA).

Methods : Seventy-four eyes from 45 patients were evaluated for longitudinal assessment based on two time-point UWFA availability. Following phase-matched pair identification, each UWFA pair was aligned and a common region of interest was determined. A semi-automated deep-learning augmented ischemia and vascular segmentation platform was utilized for feature extraction. Expert image analyst review was performed of each image and segmentation errors were corrected. GD maps demonstrating the shortest distance from the center of the optic disc while staying inside vessel masks were created. Vessel area, length and mean GD were measured. Paired t-test and Pearson correlation tests were performed.

Results : Phase-matched UWFAs for longitudinal vasculature analysis were available in 46 eyes from 32 patients with a mean follow-up interval of 2.0 years. Mean baseline panretinal ischemic index was 10.0 ± 7.2% at the first time-point and 10.9 ± 7.3% in second time-point (p<0.005). Mean vessel area, vessel length, and GD were 65.1E+4 ±10.0E+4, 12.8E+4 ± 2.0E+4 and 1005 ± 82 pixels at the first time-point and 63.4E+4 ±10.4E+4, 12.4E+4 ± 2.2E+4 and 996 ± 83 pixels at the second time-point, demonstrating a significant decrease in vessel area (p=0.016), vessel length (p=0.017) and GD (p=0.048). Mean GD independently correlated with panretinal ischemic index at both time-points (r = -0.35 p=0.018, r = -0.48 p<0.001).

Conclusions : Longitudinal ischemic index and retinal vascular parameter measurements demonstrate statistically significant progression in sickle cell retinopathy. The clinical significance of these relatively small magnitude changes remains unclear, but may provide insights into the natural history of retinal ischemia progression in sickle cell retinopathy. Further research is needed to evaluate the role of GD as an assessment biomarker in retinal vascular disease.

This is a 2020 ARVO Annual Meeting abstract.

 

Fluorescein angiography frames (A, B), ischemia segmentations (C, D), vasculature masks (E, F) and color scaled, disc centered geodesic diameter maps (G, H) of an eye with progressive sickle cell retinopathy.