Optical coherence tomography angiography and wide-field fluorescence angiography for retinal blood vessel evaluation in a rat model of endothelin-1-induced vasoconstriction

Abstract

Purpose : To evaluate vessel density changes using optical coherence tomography angiography (OCTA) and wide-field fluorescence angiography (WF-FA) in a rat model of vasoconstriction induced by intravitreal injection of endothelin-1 (ET-1).

Methods : Vehicle or ET-1 (20 pmol/eye) was injected into the vitreous body in Brown Norway rats. Retinal vessels were observed using OCTA（RS3000A; Nidek）and WF-FA (Mirante; Nidek). OCTA images (20° × 20° field) were taken using a custom-made rat-specific adapter. Retinal layers—the internal limiting membrane and the photoreceptor inner–outer segment junction—were segmented using custom-made software, and en face OCTA images of these volumes were acquired. WF-FA images (Φ110° field) were taken with a wide-field adapter. Retinal vasculature was imaged before, and every 5–10 min until 50 min after, intravitreal injection (n = 4 rats/group). OCTA and WF-FA images were enhanced and vascular binary images were generated by using the Fiji package in the ImageJ software. Vessel density was presented as vessel area/total area*100% and normalized by baseline values (100%).

Results : The binarized WF-FA images showed mainly large vessels. ET-1 caused a significant decrease in vessel density 5 min after injection, peaking at 30 min (vehicle, 97% ± 4%; ET-1, 49% ± 14％, P < 0.01) and lasting up to 50 min. The binarized OCTA image detected both capillaries and large vessels. ET-1 significantly decreased vessel density 5 min after injection; most capillaries were invisible by 10 min. Dramatically decreased vessel density was observed by 15 min (Vehicle, 88% ± 10%; ET-1, 16% ± 11％, P < 0.01), lasting up to 50 min.

Conclusions : Under the conditions in this study, WF-FA was suitable for evaluating a wide range of large vessels, and OCTA for evaluating large vessels and capillaries. OCTA and WF-FA are useful for different purposes in detailed research evaluation of retinal vasculature.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

 

Wide-field fluorescence angiography (WF-FA) (Φ110°) and optical coherence tomography angiography (OCTA) (20° × 20°) images of a rat eye after intravitreal ET-1 injection.
WF-FA (A) Pretreatment and (B) 50 min after injection. OCTA (C) Pretreatment and (D) 50 min after injection