Non‐invasive skin autofluorescence as a screening method for diabetic retinopathy

Abstract

Diabetic retinopathy (DR) is a public health problem and a common cause of blindness. It is diagnosed by fundus examination; however, this is a costly and time‐consuming method. Non‐invasive skin autofluorescence (SAF) may be an accessible, fast and simple alternative for screening and early diagnosis of DR. The aim of this study was to evaluate the accuracy of SAF as a screening method for DR. A systematic search of MEDLINE, Scopus, and Web of Science databases was performed. Random effects models for sensitivity, specificity, positive likelihood ratio (PLR) and negative likelihood ratio (NLR), diagnostic odds ratio (dOR) value and 95% CIs were used to calculate test accuracy. In addition, hierarchical summary receiver operating characteristic curves (HSROC) were used to summarise the overall test performance. Four studies were included in the meta‐analysis. Pooled sensitivity and specificity were 0.79 (95% CI 0.72–0.88; I2 = 0.0%) and 0.54 (95% CI 0.32–0.92; I2 = 97.0%), respectively. The dOR value for the diagnosis of DR using SAF was 5.11 (95% CI 1.81–14.48: I2 = 85.9%). The PRL was 2.17 (95% CI 0.62–7.64) and the NRL was 0.27 (95% CI 0.07–1.03). Heterogeneity was not relevant in sensitivity and considerable in specificity. The 95% confidence region of the HSROC included all studies. SAF as a screening test for DR shows sufficient accuracy for its use in clinical settings. SAF may be an appropriate method for DR screening, and further research is needed to recommend it as a diagnostic method.

Associations between Skin Autofluorescence Levels with Cardiovascular Risk and Diabetes Complications in Patients with Type 2 Diabetes

“…Both studies affirm the significance of SAF; the former underscores its value as an independent prognostic marker for kidney dysfunction, separate from traditional renal markers, while the latter confirms its importance concerning macroangiopathy [49,50]. From these data, it seems evident that there exists a robust and firmly established correlation between SAF and DR, likely attributable to the direct influence of AGEs on retinal microvessels [45,51]. However, the connection between SAF and neuropathy or nephropathy is less pronounced, and SAF's role and predictive values may differ across various complications, potentially due to other pathophysiological pathways beyond AGE accumulation.…”

“…Increased levels of AGEs have been correlated with DR, as evidenced by multiple studies [40][41][42][43][44][45]. Yasuda and colleagues noted a correlation between skin AGE levels and the severity of DR in T2DM patients.…”

“…The authors concluded that while SAF is unlikely to replace ocular fundus inspection, it may serve as a convenient screening technique, especially in situations with limited resources. Further research is necessary to determine the reference values and the consistent usefulness of this tool across various populations [45]. Błaszkiewicz et al describe the pathophysiological impact of AGEs on DR, noting their role in compromising neurovascular integrity through oxidative stress and inflammation The binding of AGEs to RAGE on retinal cells initiates harmful signaling pathways, especially in Müller cells.…”

The effects of advanced glycation end‐products on skin and potential anti‐glycation strategies

“…47 Skin autofluorescence (SAF) represents a non-invasive, inexpensive, highly reproducible method of measuring AGEs, which is a biomarker of skin AGEs and index of skin glycation. 48 The fluorescence intensity of the skin AGEs can be detected by specific instruments in a non-invasive way. 49,50 When the skin is irradiated with UV rays, the fluorescent AGEs accumulated in the tissue are excited and emit characteristic autofluorescence.…”