TNF and blepharitis: In patients with blepharitis and MGD, levels of metalloproteinase (MMP)-9, interleukin (IL)-1β, IL-6, IL-17, tumor necrosis factor (TNF)-α and intercellular cell adhesion molecule-1 (ICAM-1) were found to be upregulated in tear fluid, and these inflammatory markers amplify the inflammatory response, disrupt tight junctions of the corneal epithelium, and induce goblet cell apoptosis, which ultimately disrupt the stability of the tear film (8, 9).