TIMP1 and keratoconus: The natural precursor contains a signal peptide of 23 residues which are cleaved throughout the protein maturation.[23,24,25,26,27]TIMP-1 suppresses angiogenesis and controls the balance in the corneal tissue by inhibiting the action of matrix metalloproteinase to protect tissues from permanent damage.[28] Furthermore, it has been demonstrated that increased MMP and decreased TIMP levels are associated with the development of KC.[29]