Changes in Retinal Vascularization Assessed by OCTA in Type 2 Diabetic Patients with Diabetic Retinopathy

Abstract

Relevance: This study is of interest as it examines retinal microvascular changes in diabetic patients using optical coherence tomography angiography (OCTA). This novel and promising technique allows the detection of early microvascular signs in diabetes mellitus (DM), even before they are clinically evident.
Purpose: To study retinal vascularization in the superficial capillary plexus (SCP) and deep capillary plexus (DCP), as well as the choriocapillaris (CC) and the area of the foveal avascular zone (FAZ) using swept-source OCTA (DRI-Triton SS-OCT®, Topcon Corporation, Japan) in patients with type 2 diabetes mellitus (T2DM) with moderate diabetic retinopathy (DR) and without diabetic macular edema (DME).
Methods: The sample consisted of a total of 88 eyes, 54 of which belonged to the T2DM group aged between 42 and 86 years, and 34 eyes belonged to the control group aged between 47 and 83 years. They had maximum spherical ametropia of ±9.00 and ±3.00 D of astigmatism, with no other ocular pathology. All subjects underwent measurements with an autorefractometer, ocular biometry, visual acuity (VA), intraocular pressure (IOP), and OCTA in the SCP, DCP, and CC in the central, superior, temporal, nasal, and inferior sectors, and the FAZ area was also measured in both retinal plexuses. Additionally, anatomical alterations in the T2DM group were studied, and several clinical variables were collected, including the duration of the disease and parameters related to the metabolic control of DM. Non-parametric tests, specifically the Mann-Whitney U test for independent samples, were used to determine the presence of statistically significant differences (p<0.05) between groups.
Results: Regarding the study of vascular density using OCTA, the T2DM group showed statistically significantly lower results in the SCP compared to the control group in the Central, Superior, and Nasal regions, with no significant differences in the DCP and CC. Significant differences were found in the FAZ area, being larger in the T2DM group in the SCP (p<0.001), while no difference was found in the DCP between both groups. The most notable anatomical alterations in the retinal plexuses were the presence of peripheral disruption in the SCP (83.30%), the presence of microaneurysms in the DCP (81.10%), and flow changes in the DCP (81.10%).
Conclusions: The results of this study show differences in vascular density between the two groups studied, being lower in the T2DM group, with statistically significant differences at the level of the retinal SCP. Additionally, it was found that the FAZ is increased in the T2DM group in both retinal plexuses, especially in the SCP. T2DM patients with moderate DR present anatomical alterations in the SCP, DCP, and CC.