Keratoconus (KC) is a bilateral, noninflammatory, and progressive corneal ectasia that occurs mostly as a sporadic disorder, but it has long been recognized that a significant minority of patients also exhibit a family history. In recent years, several candidate genes, including VSX1 and SOD1, have been proposed and some disease-causing mutations have been identified.To investigate the role of the 2 genes in 113 Slovenian patients with sporadic and familial KC, the complete coding region with corresponding intronic sequences was analyzed. The same regions of both genes were also checked in 100 healthy blood donors. We also checked the relation of 627+23G>A polymorphism in the VSX1 gene with the hereditary form of the disease.No disease-causing mutations were identified in either gene. We did discover a significant association of 627+23G>A polymorphism distribution (VSX1) with unrelated patients diagnosed with the hereditary form of KC.The absence of pathogenic mutations in our large number of unrelated patients with KC indicates that other genetic factors are involved in the development of this disorder.