Purpose: The purpose of this study was to investigate the association between the choriocapillaris microcirculation and the visual function and cone photoreceptor structure in patients with diabetes.
Methods: Thirteen control subjects and 26 patients with type 2 diabetes were recruited. The patients with diabetes were divided into three groups based on the grade of diabetic retinopathy (DR). The retinal sensitivity (RS) was evaluated using microperimetry. Cone photoreceptor mosaics were imaged using an adaptive optics retinal camera, and the cone heterogeneity packing index (HPi) was calculated. Optical coherence tomography angiography (OCTA) images of the choriocapillaris were obtained using spectral-domain OCTA, and the area of flow deficit (FD) was evaluated. All parameters were evaluated in the foveal and parafoveal areas.
Results: The study included four patients with diabetes without retinopathy, 12 patients with nonproliferative diabetic retinopathy (NPDR), and 10 patients with proliferative diabetic retinopathy (PDR). The foveal and parafoveal FDs were correlated significantly (fovea, r = -0.58; P = 0.046 and r = -0.82; P = 0.003; parafovea, r = -0.59; P = 0.044 and r = -0.72; and P = 0.019, respectively) with the RS in patients with NPDR and PDR, but not in control and no diabetic retinopathy (NDR) groups. There were no differences in the foveal HPi among the groups.
Conclusions: Impaired choriocapillaris microcirculation is associated with impaired visual function but not cone photoreceptor integrity in eyes with DR.