Evaluation of retinal microcirculation in diabetic patients using optical coherence tomography angiography

Purpose
The aim of this study was to compare the length and the area of the retinal vascular network in diabetic and healthy eyes by optical coherence tomography angiography.

Material and methods
Ninety eyes of 49 patients with type 2 diabetes and non-proliferative diabetic retinopathy and 70 eyes of 35 healthy volunteers were enrolled in a prospective, observational study. All subjects were examined using optical coherence tomography (RTVue XR Avanti; Optovue). En-face optical coherence tomography angiography images of the superficial and deep capillary plexus, outer retina and choriocapillaris were evaluated using the ImageJ software. The regularity of the vas­cular network, a subjectively evaluated capillary density, the presence of vascular loops, microaneurysms, ischemic areas, intraretinal microvascular abnormalities and neovascularizations were all evaluated based on angioflow scans.

Results
The superficial retinal capillary network area was significantly (p< .0001) smaller in diabetic patients (22.257 ± 6.316 pixels) than in healthy subjects (28.355 ± 3.793 pixels). The superficial retinal capillary network length was significantly (p< .0001) smaller in diabetic patients (9.313 ± 2.790 pixels) than in healthy subjects (11.360 ± 1.809 pixels). The deep retinal capillary network area was significantly (p< .0001) smaller in diabetic patients (32.134 ± 8.926 pixels) than in healthy subjects (41.318 ± 5.247 pixels). Similarly, the deep retinal capillary network length was significantly (p< .0001) smaller in diabetic patients (14.282 ± 3.416 pixels) than in healthy subjects (16.909 ± 1.619 pixels). Morphological vascular anomalies are more common in patients with diabetes.

Conclusions
Optical coherence tomography angiography offers non-invasive monitoring of the retinal microcirculation in diabetic patients. Capillary length and area are easily measurable parameters.