Purpose: We compared the area of the foveal avascular zone (FAZ) and macular capillary network density at different retinal layers using swept-source optical coherence tomography angiography (OCT-A) in normal individuals and patients with diabetic retinopathy (DR).
Methods: Images (a 3 × 3 mm cube centered on the fovea) were acquired in 40 eyes of 22 normal individuals and 28 eyes of 18 patients with varying levels of DR using a swept-source OCT-A device (central wavelength 1050 nm; A-scan-rate of 100,000 scans per second). En face images of the retinal vasculature were generated from the superficial and deep retinal layers (SRL/DRL). Quantitative analysis of the vessel density (VD) and FAZ area was performed. Vessel density was assessed as the ratio of the retinal area occupied by vessels.
Results: Among the DR subjects (mean age, 72 years; 61% male), 35.7% of the eyes had mild, 35.7% moderate, and 7.1% severe nonproliferative DR (NPDR), and 21.4% and proliferative DR (PDR). The mean FAZ area in patients with DR and in normal individuals was 0.518 and 0.339 mm2, respectively, for the SRL (P = 0.003), and 0.615 and 0.358 mm2, respectively, for the DRL (P < 0.001). The mean VD (ratio) at the SRL and DRL was statistically significantly lower in patients with DR (SRL, P < 0.001; DRL, P = 0.028).
Conclusions: Swept-source OCT-A of the microcirculation in eyes of patients with DR can be used to quantitatively demonstrate alterations in the FAZ and VD in the SRL/DRL of the macula compared to normal eyes. Future longitudinal studies may use these metrics to evaluate changes over time or in response to treatment.