The affected numbers are small, but given the growing body of evidence of pathogenic segregating changes in VSX1 in these cohorts, the expression in keratocytes as part of wound healing, and the documented association of PPCD and keratoconus, it seems likely that the role of VSX1 is real, but not significant in terms of actual numbers. This evidence concerns the gene VSX1 and posterior polymorphous corneal dystrophy.