OCTA shows in vivo alterations of retinal capillary network in diabetic eyes

Issue: January 2016

VIENNA — OCT angiography offers for the first time the possibility to study in vivo the architecture of the retinal capillary network and to image separately the superficial and deep capillary plexus.

OCT angiography (OCTA) images of healthy eyes obtained with the AngioVue system (Optovue) and presented at the Advanced Retinal Therapy meeting by Bénédicte Dupas, MD, showed that the two plexuses have separate networks with different architectures. While in the superficial and deep capillary plexus there is a one-to-one connection between capillaries, the deep capillary plexus is organized in capillary vortexes and seems predominantly venous.

“This could explain some differences in flow resistance and perfusion of each network and some complications in diseases,” Dupas said.

Alterations in eyes with diabetic retinopathy were visible as non-perfused areas in the superficial capillary plexus of 100% of eyes, while the deep capillary plexus had less frequent non-perfused areas but an overall markedly disorganized architecture.

OCTA was found to be less sensitive than fluorescein angiography (FA) in detecting microaneurysms.

“Only 60% of microaneurysms detected on FA were visible on OCTA. This could be due to a low flow or absence of circulating blood cells in the microaneurysm,” Dupas said.

In eyes with diabetic macular edema, no capillaries were visible inside the cyst, possibly due to capillary closure or displacement toward the periphery of the cyst. In some of these eyes, in which the edema had resolved after intravitreal anti-VEGF injection, capillaries only partially reappeared after retinal drying but the area of the cyst remained mainly avascular.

“This could explain why some patients do not recover vision after reabsorption of the edema,” Dupas said. – by Michela Cimberle

Disclosure: Dupas reports she is a consultant to Bayer, Carl Zeiss Meditec, Novartis and Allergan.