Optical coherence tomography angiography — novel method to access retinal microcirculation in patients with diabetic retinopathy

Abstract

Introduction. Optical coherence tomography angiography (OCTA) is a novel technique that allows visualization of retinal capillary network without the need for contrast usage. Being easy to perform and non-invasive, it might become significantly competitive to fluoroangiography. Material and methods. The study included 45 patients (90 eyes) with diabetes type 1 and 2 and nonproliferative and proliferative diabetic retinopathy as well as 35 healthy volunteers (70 eyes) as a control group. Beside full ophthalmic examination, all patients underwent OCTA (RTVue XR Avanti; Optovue) examination. Obtained images were used to assess the presence of morphologic changes of the retina characteristic for diabetic retinopathy (capillary density and regularity as well as occurrence of microaneurysms, ischemic areas, intraretinal microvascular abnormalities and neovascularizations). The assessment was carried out on two levels of retinal capillary plexus. Additionally, measurement of foveal avascular zone (FAZ) was performed. The results were compared with those obtained from the control group. Results. All examined eyes in the studied group exhibited one or more anomalies characteristic of diabetic retinopathy as seen on the OCTA scans, both in superficial and deep vascular plexus. In the control group we have detected capillary irregularity (9% in a superficial and 11% in a deep vascular plexus) and capillary rarefication (7% in a superficial and 9% in a deep vascular plexus) and no other anomalies were found. Mean FAZ area measured in superficial vascular plexus was 382 ± 134 square micrometers and was significantly larger (p < 0,001) in comparison to the control group (259 ± 103 square micrometers). Conclusions. Optical coherence tomography angiography is a useful diagnostic tool used to assess vascular changes in the retinal microcirculation in diabetic patients. Its main advantages are noninvasiveness, repeatability and a high quality of images acquired from the chosen level of the retina.