MMP-9 participates in remodeling of the extracellular matrix after wounding of the corneal surface and is implicated in the pathogenesis of sterile corneal ulceration, ocular allergy, fungal keratitis, burns, advanced keratoconus with irregular surface, active pterygia, conjunctivochalasis, blepharitis, and dry eye9–16. This evidence concerns the gene MMP9 and keratoconus.