Ultrawide-Field Swept-Source OCTA in Detecting Retinal and Choroidal Microcirculation Changes in Diabetes Patients Without Retinopathy

<b>Purpose:</b> Given the substantial damage to visual function caused by diabetic retinopathy, this study explored the changes in the fundus microcirculation of diabetic patients without diabetic retinopathy to provide a basis for the prevention and early detection of diabetic retinopathy. <b>Methods:</b> This clinical observational study included 162 eyes of diabetic patients without clinical diabetic retinopathy and 108 healthy eyes. Retinal and choroidal parameters, namely, the foveal avascular zone (FAZ) and vessel density of the superficial capillary plexus (SCP), deep capillary plexus (DCP), full retina and large and middle choroidal vessel (LMCV) layers, were measured in the central and peripheral areas of 24 × 20 mm² ultrawide-field swept-source optical coherence tomography angiography (UWF-SS-OCTA) images. The Mann‒Whitney U test or Wilcoxon signed-rank test was used for comparisons between groups, and the Kruskal‒Wallis H test was used for comparisons among multiple groups, followed by Bonferroni correction for multiple comparisons. <b>Results:</b> The FAZ in the diabetic group was greater than that of the control group. The diabetic group had lower vessel densities in the SCP (0-3, 4-6, and 13-24 mm diameter ranges), DCP (0-3, 4-6 and 7-12 mm diameter ranges), full retina (0-3 and 4-6 mm diameter ranges), and LMCV layers (4-6 and 13-24 mm diameter ranges) (<i>p</i> < 0.05). Significant differences (<i>p</i> < 0.05) were observed between the vascular density of the SCP (diameter ranges 0-3 and 7-12 mm), DCP, full retina, and LMCV layers (4-6 mm range) in all disease duration groups and those in the control group. Pairwise comparison showed that the vascular density decreased more significantly in the group > 15 y group (<i>p</i> < 0.05). <b>Conclusion:</b> Decreased retinal choroidal microcirculation occurs in diabetic patients before clinical retinopathy develops and becomes more pronounced with increasing disease duration, suggesting that diabetic patients should undergo regular fundus examinations to detect and potentially prevent diabetic retinopathy as early as possible.