Imaging Features of Intraretinal Microvascular Abnormalities in Diabetic Retinopathy

Abstract

Purpose : To compare characteristics of intraretinal microvascular abnormalities (IRMA) on color fundus photography (CFP) to UWF-FA. We hypothesize that IRMA on CFP have similar characteristics to corresponding lesions seen on UWF-FA.

Methods : Participants with ultrawide field imaging at baseline and a DR Severity Scale of 47/53 (moderate and moderately severe NPDR), enrolled in the Regeneron Study were included. The location of up to three IRMA patches per eye were annotated on standard 7 field and 4 field CFP and the characteristics documented included wiry appearing vessels, branching and tortuous vessels, low-lying (intraretinal) vessels when viewed under stereoscope imaging, and vessels that were located between large retinal vessels. Wiry appearing vessels are defined as vessels small in diameter, while branching and tortuous vessels contained various twists and turns. Corresponding locations were examined on UWF-FA and the same characteristics were documented, and with an added characteristic of vessels containing leakage within vascular tips (Fig. 1).

Results : A total of 63 IRMA were identified from 30 eyes with paired CFP and UWF-FA. On CFP, 92% of IRMA lesions showed wiry appearing vessels, 86% showed branching and tortuous vessels, 92% of vessels appeared to be low lying vessels when viewed under stereoscope imaging, and 100% of IRMA were located between large retinal vessels. On corresponding UWF-FA, 91% of lesions showed wiry appearing vessels, 79% showed branching and tortuous vessels, 70% of vessels did not have leakage present at vascular tips, and 95% of IRMA were located between large retinal vessels. When comparing exact lesions between imaging technologies, 94% of wiry appearing vessels, and 89% of branching and tortuous vessels were in exact agreement with each other.

Conclusions : The current gold standard for identifying IRMA is through CFP. Our data suggests that IRMA lesions on UWF-FA have similar features to lesions found on CFP and present as wiry, branching and tortuous vessels, located between large blood vessels with minimal leakage on UWF-FA. Although CFP is recommended for identification of IRMA lesions, it has limitations such as image quality being dependent on pupil diameter, and its susceptibility to opacities of the media. UWF-FA can be a valuable adjunct in evaluating IRMA and can be used to confirm IRMA on CFP.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.