TNF and retinal disorder: Furthermore, another important finding is the strong association between nephropathy and retinopathy; in fact, in our patients a significant correlation among HbA1c, body mass index (kg/m2), glomerular filtration rate (GFR), albuminuria, blood urea nitrogen, and levels of TNF-alpha in the tears has been found, further confirming that TNF-alpha tear levels may be considered a good predictor of microvascular complications.