TNF and non-proliferative diabetic retinopathy: In a recent cross-sectional study in Asian patients with DR, there was evaluated the differences in Total Protein Concentrations (TPC) and TNF-α in tears correlated with the three stages of NPDR (mild, moderate and severe), they found a decreased in TPC in moderate and severe NPDR compared with higher concentrations of TNF-α in the same stages, but in mild NPDR and patients without retinopathy the concentrations were similar.