Purpose To report outer retinal structural changes associated with macular capillary non-perfusion at the level of deep capillary plexus (DCP) in diabetic patients. Design Prospective observational cross-sectional study. Methods The study included 14 eyes of 10 patients who were diagnosed as having diabetic retinopathy. To study the outer retina and localize areas of capillary non-perfusion at the superficial (SCP) or DCP, we used the spectral domain optical coherence tomography (SD-OCT) device (RTVue-XR Avanti, Optovue Inc, Fremont, California) with split-spectrum amplitude-decorrelation angiography (SSADA) software for optical coherence tomography angiography (OCTA). Two independent masked graders (F.S. and A.A.F.) qualitatively evaluated SD-OCT scans as either normal or having outer retina disruption. The angiographic images were examined to define the presence and location of capillary non-perfusion. Results Eight eyes showed outer retinal disruption on SD-OCT that co-localized to areas of enlarged foveal avascular zone, enlarged areas of no flow between capillaries and capillary non-perfusion of the DCP. Six eyes without outer retinal changes on SD-OCT showed robust perfusion of the DCP. Conclusions Using OCTA, this study shows that macular photoreceptor disruption on SD-OCT in patients with diabetic retinopathy corresponds to areas of capillary non-perfusion at the level of DCP. This is important in highlighting the contribution of the DCP to the oxygen requirements of the photoreceptors as well as the outer retina in diabetic macular ischemia.

M1 patients with no or mild signs of retinopathy have reduced parafoveal vessel density in the DCP on OCTA when compared to non-diabetic controls. These OCTA findings suggest that parafoveal capillary nonperfusion is an early process in DM1-related retinal changes and occurs initially at the level of the DCP. Further investigation is needed to understand the prognostic role of these vascular changes.

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Diabetic macular ischemia (DMI) is a phenotype of diabetic retinopathy (DR) associated with chronic hypoxia of retinal tissue. The goal of this prospective observational study was to report evidence of photoreceptor abnormalities using adaptive optics scanning laser ophthalmoscopy (AOSLO) in eyes with DR in the setting of deep capillary plexus (DCP) non-perfusion. Eleven eyes from 11 patients (6 women, age 31–68), diagnosed with DR without macular edema, underwent optical coherence tomography angiography (OCTA) and AOSLO imaging. One patient without OCTA imaging underwent fluorescein angiography to characterize the enlargement of the foveal avascular zone. The parameters studied included photoreceptor heterogeneity packing index (HPi) on AOSLO, as well as DCP non-perfusion and vessel density on OCTA. Using AOSLO, OCTA and spectral domain (SD)-OCT, we observed that photoreceptor abnormalities on AOSLO and SD-OCT were found in eyes with non-perfusion of the DCP on OCTA. All eight eyes with DCP non-flow on OCTA showed photoreceptor abnormalities on AOSLO. Six of the eight eyes also had outer retinal abnormalities on SD-OCT. Three eyes with DR and robust capillary perfusion of the DCP had normal photoreceptors on SD-OCT and AOSLO. Compared to eyes with DR without DCP non-flow, the eight eyes with DCP non-flow had significantly lower HPi (P = 0.013) and parafoveal DCP vessel density (P = 0.016). We found a significant correlation between cone HPi and parafoveal DCP vessel density (r = 0.681, P = 0.030). Using a novel approach with AOSLO and OCTA, this study shows an association between capillary non-perfusion of the DCP and abnormalities in the photoreceptor layer in eyes with DR. This observation is important in confirming the significant contribution of the DCP to oxygen requirements of photoreceptors in DMI, while highlighting the ability of AOSLO to detect subtle photoreceptor changes not always visible on SD-OCT.