The published literature and our previously published data demonstrated elevated levels of MMP-9 in the epiretinal membranes and vitreous fluid from patients with proliferative diabetic retinopathy (PDR) and increased MMP-9 expression in the retinas of diabetic rodents [13, 15, 16, 22–24]. The gene discussed is MMP9; the disease is proliferative diabetic retinopathy.