Swept-Source Optical Coherence Tomography Angiography Parameters Correlate with Leakage and Ischemic Indices from Ultra-Widefield Fluorescein Angiography in Diabetic Retinopathy

Abstract

Purpose : To evaluate the utility of Swept-Source optical coherence tomography angiography (SS-OCTA) in assessing retinal ischemia in diabetic retinopathy (DR) by comparing parameters of retinal perfusion with ultra-widefield Fluorescein Angiography (UWFA) ischemia and leakage metrics.

Methods : This is a retrospective review of consecutive DR patients who had both SS-OCTA and UWFA at the same visit. SS-OCTA was performed on the Zeiss Plex Elite platform. 6x6 and 12x12 SS-OCTA images were analyzed. Perfusion density (defined as the total area of perused vasculature per unit area) as well as vessel density (total length of perfused vasculature per unit area) were obtained. UWFA metrics were quantified using a customized feature analysis platform that detected leakage indices automatically (3-disc diameter and 6-disc diameter areas centered on the macula) and ischemia indices manually by a masked reviewer (n=28). Spearman’s correlations were used to compare the OCTA and FA features.

Results : 168 eyes were included in the 6x6 SS-OCTA group, and 98 eyes in the 12x12 SS-OCTA group. Increased 3-disc leakage on FA was associated with reduced perfusion and density parameters in both superficial and deep 6x6 SS-OCTA and trended with 12x12 SS-OCTA. For example, increased 3-disc leakage on FA associated with both reduced superficial perfusion (R=-0.1896, p=0.0138) and superficial density (R=-0.1760, p = 0.0224) on the 6x6 SS-OCTA average field of view.
Manual ischemia measurements were performed on 28 eyes. Of the fifteen eyes that had both FA and 12x12 SS-OCTA imaging, increased posterior pole ischemia on FA was associated with reduced superficial perfusion (r=-0.5922, p= 0.0200) and density (r=-0.5036, p=0.0432) on SS-OCTA average field of view. Of the twenty-four eyes that had both UWFA and 6x6 SS-OCTA imaging, increased macular ischemia on FA was associated with decreased superficial and deep perfusion and density parameters (p<0.05).

Conclusions : Swept-Source OCTA vascular perfusion and densities in both the superficial and deep plexuses correlate with ischemia and leakage metrics quantified from FA. Further larger investigations will verify whether macular centered non-invasive OCTA can substitute for FA in assessing retinal ischemia in DR patients and other retinal pathologies.

This is a 2020 ARVO Annual Meeting abstract.