Given that PEDF and MMP-2 and -9 coexist in the dry eye milieus, dosing with exogenous PEDF and 29-mer to overwhelm the enzymatic activity of MMP-2 and -9 and suppress the production of MMP-9 from CECs would be beneficial for DED therapy. This evidence concerns the gene MMP9 and Keratoconjunctivitis sicca.