Role of Optical Coherence Tomography Angiography to differentiate Intraretinal microvascular abnormalities and retinal neovascularization in Diabetic Retinopathy

Objective: To assess proliferative diabetic retinopathy (PDR) and to describe the difference in angiographic representation of new vessels (NVs) and Intra retinal microvascular abnormalities (IRMA) on optical coherence tomography angiography (OCTA).

Methods: A cross-sectional observational study was performed at ISRA Postgraduate Institute of Ophthalmology, Karachi, from March 2018 to September 2018. Forty-two eyes of 21 patients with history of diabetes mellitus (DM) were examined. Twenty-eight eyes with a clinical diagnosis of severe non proliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR) according to early treatment diabetic retinopathy study (ETDRS) were included and evaluated using Swept source optical coherence tomography angiography (SS-OCTA). Then face wide field SS-OCTA images and co registered structural optical coherence tomography (OCT) with flow overlay were used to distinguish the features of IRMA and retinal NVs.

Results: Forty-two eyes (21 patients) were examined clinically. Fourteen eyes had moderate NPDR, 15 had severe NPDR and 13 eyes had changes consistent with PDR. After clinical diagnosis, we included 28 eyes in our study based on inclusion criteria. These 28 eyes went through SS-OCTA evaluation and we observed 15 cases with PDR and 13 with severe NPDR changes. The OCTA and clinical diagnosis were similar except in 2 eyes, which is critical but not statically significant showing the importance of this noninvasive technology.

Conclusions: Widefield OCTA can work as an alternative to fundus fluorescein angiography (FFA) in the diagnosis of diabetic retinopathy (DR). As it is a non-invasive and depth encoded technique so can be used frequently to monitor the retinal changes and their progression.