Normative Perfusion Indices in the Diabetic Population

Diabetes damages retinal capillaries before clinical changes appear. Optical coherence tomography can quantify changes in vessel length density and vessel area density in diabetics without retinopathy and can lead to a reduction of these metrics in different capillary plexuses. The mean values of vessel densities vary according to the device used. Here, we review the values of vessel length density, vessel area density, and foveal avascular zone metrics in diabetics without retinopathy in a 3 x 3 mm map of the most used commercially available devices. We included measurements for the superficial, intermediate, and deep capillary plexuses in the parafoveal region. The information refers to adult type 2 diabetic people according to densities in the foveal, parafoveal, and whole map measurements. We also included parafoveal distribution by field as well. There are references to the foveal avascular zone—a common variable measured to detect ischemia in patients with diabetic retinopathy—and we report them for both superficial and deep capillary plexuses. We also include the proposed cut-off values for normality for metrics of the superficial capillary plexus and propose an explanation for the differences that exist between measurements with the same device as related to diabetes duration. 

Keywords: Area, Deep capillary plexus, Diabetes, Foveal avascular zone, Middle capillary plexus, Perimeter, Superficial capillary plexus, Vessel area density, Vessel length density.