To determine whether SF downregulates NADPH oxidase (Nox)-2 and Nox-4 levels and upregulates Nrf-2 and HO-1 levels in the KC mechanical microenvironment, we analyzed changes in the levels of proteins associated with oxidative stress in all groups by Western blot (WB) and RT‒qPCR analyses. This evidence concerns the gene NOX4 and keratoconus.