In fact, proinflammatory cytokines (IL-1, IL-6, TNF-α, and TGF-β), oxidative stress, or degradation of collagens by metalloproteases (MMP-1, MMP-3, and MMP-9) has been implicated in keratoconus pathophysiology [3, 21–25]. This evidence concerns the gene MMP9 and keratoconus.