Radial peripapillary capillary changes and retinal nerve fiber layer alterations in diabetic foot ulcers with mild-to-moderate nonproliferative diabetic retinopathy: an OCTA study

Background/aim: This study aimed to evaluate the impact of diabetic foot ulcers (DFUs) on retinal microvascular changes, specifically the radial peripapillary capillary (RPC) vessel density and retinal nerve fiber layer (RNFL) thickness in patients with mild-to-moderate nonproliferative diabetic retinopathy (NPDR). Materials and methods: Ninety participants were enrolled and divided into three groups: 30 patients with DFUs and mild-to-moderate NPDR, 30 patients with NPDR but without DFUs, and 30 healthy controls. RPC density and RNFL thickness were evaluated using optical coherence tomography angiography (OCTA), a noninvasive imaging method. Comparisons between groups were made with statistical adjustments, including optic disc area. Results: Patients with DFUs exhibited significantly lower RPC vascular density across multiple quadrants than those without DFUs and healthy controls (p < 0.001). Furthermore, RNFL thickness was significantly increased in the DFU group, particularly in the inferior-hemi (p < 0.001) and temporal-inferior (p < 0.001) quadrants. The optic disc area was significantly larger in the DFU group (p = 0.017), which may have influenced the RNFL measurements. Conclusion: The study underscores notable alterations in RPC density and RNFL thickness among patients with DFUs and mild-to-moderate NPDR. These alterations may reflect systemic microvascular impairment, potentially exacerbated by systemic inflammation, or changes suggestive of reactive gliosis, though further validation is needed. These findings underscore the need for early ophthalmological evaluation and a comprehensive approach to managing both peripheral and ocular diabetic complications. Future studies incorporating systemic inflammatory biomarkers and functional visual assessments are needed to explore the mechanisms underlying these retinal changes.