Comparison between the Foveal Avascular Zone and Macular Capillary Network Density in Diabetic Retinopathy and Normal Retina

Abstract

Background: Diabetic retinopathy (DR) is mostly a vascular disease where the development of macular oedema and proliferative retinopathy are major causes of visual impairment. Enlargement of the foveal avascular zone (FAZ) is associated with visual deterioration in patients with diabetic retinopathy. Objective: To evaluate the foveal avascular zone (FAZ) and perifoveal capillary network density in the superficial retinal layer (SRL) and deep retinal layer (DRL) in patients with varying severities of diabetic retinopathy (DR). Patients and methods: This is a prospective comparative randomized case-control study consisting of 77 eyes divided into two groups, each group underwent imaging using OCT-A device. Group one: 37 healthy control eyes, and group two: 40 eyes with DM of different degrees of diabetic retinopathy. Subjects were imaged between September 2019 and February 2020 at Kasr El-Ainy Teaching Hospital. Results: The FAZ area at the levels of the superficial and deep vascular networks of eyes with DR were found to be larger compared with those of age-matched healthy controls, and as would be expected, control eyes had higher vascular density in both networks compared with the diabetic eyes. Furthermore, eyes with worse DR stage showed larger FAZ area and lower vascular density values. This study also showed that angiographic parameters, namely FAZ area and vessel density (VD) correlated with best corrected visual acuity. Conclusion: Our study revealed that vascular density and FAZ area can be quantified in DR eyes in a rapid, automated, and noninvasive manner with OCTA. Also foveal avascular zone area and vascular density as measures of DMI correlate with visual acuity in patients with DR.