IL17A and keratoconus: To begin addressing this question, we quantified TH1 cytokines (IL-12, IFN-γ and TNF-α), TH2 cytokines (IL-4, IL-10 and IL-13), the TH17 representative cytokine IL-17, and other inflammatory cytokines/chemokines (IL-1β, IL-6, and RANTES or CCL5) in tear fluids and serum samples of keratoconus patients and control subjects.