Many studies conclude that VSX1 is likely to be involved in keratoconus pathogenesis,[31, 36, 38–49] while a similar number of studies do not find evidence of association.[50–63] Similarly, the superoxide dismutase gene (SOD1) has been screened in several populations including Slovenian,[53] Iranian,[45, 63] Italian,[43] Greek,[59] Saudi Arabian[64] and multiethnic[33] cohorts. This evidence concerns the gene SOD1 and keratoconus.