TIMP1 and retinopathy of prematurity: The presence of activated MMP-9 in the vitreous along with elevated levels of TIMP1, TIMP2, and α2 macroglobulin in our ROP patients and presence of blood component proteins like apolipoproteins (Figures 1A and 3A) explained its role in the degradation of the basement membrane of blood vessels, seeping out into the vitreous along with the other blood components, thereby causing vitreous hemorrhage and vitreous liquefaction.