TNF and keratoconus: In addition, the serum cytokine assays were used to determine the effects of ketamine on inflammatory cytokine levels which showed a remarkably increased level of TNF-α (KC versus control; 193.59 ± 282.17 versus 98.43 ± 85.48 pg/mL) and IFN-γ (369.78 ± 564.56 versus 0 pg/mL; p < 0.001) in KC cases (Figure 3(b)).