TNF and dry eye syndrome: According to Luo et al., tear film hyperosmolarity has been shown to induce dry eye syndrome through inflammatory cytokines such as interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-alpha), and matrix metallopeptidase 9 (MMP-9), which activate the mitogen active protein kinase signal (MAPK) pathway leading to ocular surface damage and dry eyes [28]. Iskeleli et al. postulated that disruptions of the normal composition, quantity, and physiology of the ocular tear film can cause a vicious cycle of increased tear film evaporation and subsequent dry eye symptoms [29].