Early peripapillary neurovascular injury and its relevant systemic factors in type 2 diabetic patients without...

To determine the ability of peripapillary neurovascular units (NVU) to detect early changes in the retinal microvasculature and microstructure, and to explore systemic factors linked to the peripapillary NVU injury in type 2 diabetic patients without clinically detectable retinopathy (NDR).

Fifty-two NDR patients (mean age 51.08 ± 9.60 years; 24 females; diabetes duration 8.74 ± 6.71 years) and 42 age- and sex-matched healthy controls (mean age 50.24 ± 7.97 years; 20 females) were recruited for this prospective, cross-sectional study. Retinal microvascular and microstructural networks were visualized using spectral domain optical coherence tomography angiography. Quantitative analysis of radial peripapillary capillary (RPC) density and peripapillary retinal nerve fiber layer (p-RNFL) thickness was automatically performed using the device's software, with segmentation of retinal regions into intra-optic disc and peripapillary zones. The peripapillary area was further subdivided into eight sectors for detailed regional assessments.

Compared to controls, the RPC density in eight sectors and p-RNFL thickness in four sectors were significantly reduced in NDR patients (P < 0.05). Receiver operating characteristic curve analysis showed that the composite index of the RPC density and p-RNFL thickness was generally superior to those of each single indicator in differentiating NDR patients from controls (the highest AUC = 0.745, P < 0.001). Univariate linear regression analyses revealed significant correlations between glycated hemoglobin (HbA1c), urinary microalbuminuria, blood urea, albumin to creatinine ratio, and decreased RPC density (P < 0.05). Additionally, age, intraocular pressure, blood urea, blood creatinine and estimated glomerular filtration rate (eGFR) were significantly correlated with p-RNFL thickness thinning (P < 0.05). Multivariate linear regression analysis showed that HbA1c and blood urea were the most significant factors for RPC impairment, while eGFR was correlated with p-RNFL defects (P < 0.05).

Peripapillary NVU assessment may be valuable for diagnosing, monitoring and intervening in retinal microvascular and microstructural changes associated with DM. HbA1c level and renal function indicators represented by blood urea and eGFR, were the most important systemic factors underlying peripapillary NVU changes.