TNF and atopic conjunctivitis: Abbreviations: KC = Keratoconus, CLEK = Collaborative Longitudinal Evaluation of Keratoconus, SAC = Seasonal Allergic Conjunctivitis, PAC = Perennial Allergic Conjunctivitis, VKC = Vernal Keratoconjunctivitis, IOP = Intraocular Pressure, CCT = Central Corneal Thickness, TNF-α = Tumor Necrosis Factor-Alpha, IL = Interleukin