Swept-source OCT imaging of the foveal avascular zone and macular capillary network in diabetic retinopathy

Abstract

Purpose : To analyze the area of the foveal avascular zone and the macular capillary network at different retinal layers using swept source OCT-angiography in normal individuals and patients with diabetic retinopathy.

Methods : OCT-Angiography images were acquired in 40 eyes of 22 normal individuals and 17 eyes of 11 patients with diabetic retinopathy using a swept source optical coherence tomography (DRI OCT Triton, TOPCON) device, with a central wavelength of 1050nm and an A-scan-rate of 100,000 scans per second. Scans were taken from 3x3 mm cubes centered on the fovea. En-face images of the retinal vasculature were generated from the superficial and deep retinal layer (SRL/DRL). Quantitative Analysis of the FAZ area and the vessel density was performed using the publically available GNU Image Manipulation Program (GIMP) 2.8.14 (http://gimp.org). Vessel density was assessed as the ratio of the retinal area occupied by vessels.

Results : The mean age of the diabetic retinopathy subjects was 71 years (54 – 93), and 63% were male. 36.5% of the eyes had mild and moderate NPDR, 36.5% had severe NPDR, and 27% had PDR. The values for mean ± SD area of foveal vascular zone (FAZ) and vessel density (ratio) in the macula is shown in Table 1. The mean area of the foveal avascular zone (FAZ) was 0.528 mm² in patients with diabetic retinopathy and 0.339 mm² in normal individuals for the SRL (p<0.05), and 0.553 mm² and 0.358 mm² for the DRL (p<0.05). The mean vessel density (ratio) at the SRL and DRL was statistically significantly lower in patients with diabetic retinopathy (SRL p<0.001, DRL p=0.037).

Conclusions : Quantitative analysis of capillary vessel density can be performed using swept source OCT angiography. The foveal avascular zone was significantly larger in patients with diabetic retinopathy, whereas the macular capillary density was significantly lower at both the superficial and the deep retinal layers, compared with healthy individuals.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

 

Table 1. Mean and standard deviation (SD) of the macular vessel density and FAZ area in patients with diabetic retinopathy and healthy individuals at the superficial and deep retinal layer (SRL/DRL).