Optical coherence tomography angiography findings of neurovascular changes in type 2 diabetes mellitus patients without clinical diabetic retinopathy

Abstract

Aims: To evaluate the effect of early screening with OCTA in type 2 diabetes mellitus (T2DM) patients without clinical DR (NDR).

Methods: This was a cross-sectional case-control clinical study. Eighty-four eyes of 84 patients (44 T2DM and 40 control subjects) were included. Images were obtained using AngioVue software 2.0 of the OCTA device. Foveal avascular zone (FAZ) area, FAZ perimeter (PERIM), choriocapillary flow area (CCF), acircularity index (AI), foveal vessel density in a 300-µm-wide region around FAZ (FD), macular-associated vessel density (VD) and optic disc-associated capillary density (CD) were compared between the T2DM and control groups. In the T2DM group, the correlations between the above parameters and best-corrected visual acuity (BCVA) were assessed.

Results: Enlarged FAZ, increased PERIM, reduced CCF, reduced parafoveal VD and decreased CD inside the disc were significantly more obvious in the NDR subjects than in the control subjects (FAZ 0.43 ± 0.13 versus 0.37 ± 0.08 mm², p = 0.02; PERIM 2.60 ± 0.45 versus 2.41 ± 0.28 mm, p = 0.04; CCF 1.94 ± 0.28 versus 2.05 ± 0.11 mm², p = 0.02; superficial parafoveal VD 48.01 ± 3.41 versus 50.74 ± 3.67%, p = 0.003; deep parafoveal VD 51.60 ± 3.52 versus 54.45 ± 4.19%, p = 0.004; CD inside disc 49.75 ± 4.84 versus 53.19 ± 4.04%, p = 0.003). In the NDR subjects, logMAR BCVA (β = - 0.55, p < 0.01) and FAZ (r = - 0.62, p < 0.01) showed a significant negative correlation with superficial total VD, respectively.

Conclusions: Preclinical DR can be detected by OCTA. Parameters such as FAZ, PERIM, CCF, VD and CD may be useful for early detection of microvascular impairments in DM patients with NDR. Superficial VD and FAZ are possible sensitive visual acuity predictors in NDR subjects. OCTA may be a promising non-invasive tool in daily DR screening.

Keywords: Diabetic retinopathy; Early screening; Neurovascular changes; Optical coherence tomography angiography.