TNF and dry eye syndrome: Studies have shown elevated levels of various cytokines, including interleukins (ILs)-1, 4, 8, 10, 17A, and 6; matrix metalloproteinase (MMPs)-3 and 9; tumor necrosis factor-beta (TNF-β); and tumor necrosis factor-alpha (TNF-α) in dry eye patients, and their levels correlate with disease severity [13,14,15].