There was a statistically significant decrease in the IL-@ , IL-@ , IL-@ , and TNF - concentrations and a statistically significant increase in the catalase , peroxiredoxin @ , superoxide dismutase @ ( SOD @ ) , and thioredoxin mean fluorescence intensity ( MFI ) of tears in the preservative-free group at @ , @ , and @ months compared to initial values , respectively ( P < @ ) .