VSX1 and keratoconus: VSX1 (Visual system homeobox 1), TIMP3, TGFBI, ZEB1, filaggrin (FLG) and several collagen genes, such as COL4A3, COL4A4 AND COL5A1, have been associated with keratoconus, while the distinct potential loci, which have been described, include 3p14-q13, 5q21, 5q32 and 14q11.