Early evidence for MMPs producing ECM remodeling that enhances aqueous humor outflow through the TM was provided by a study using perfused human anterior segment organ cultures.36 The addition of recombinant MMP-2, MMP-3, or MMP-9 resulted in a reversible increase in outflow facility, whereas inhibition of endogenous MMP activity reduced outflow facility.36 More recently, altered structural organization of the TM and early-onset ocular hypertension were observed in MMP-9 knockout mice, suggesting that remodeling of the TM by MMP-9 is needed to enhance outflow and maintain IOP homeostasis.37 The gene discussed is MMP9; the disease is ocular hypertension.