Abstract:

Matrix metalloproteinases (MMPs) are a group of endogenous protease which degrades extracellular matrix system. Their inhibitors, tissue inhibitor of metalloproteinases (TIMPs) and MMPs systems, degrade and restore the extracellular matrix (ECM). Expression level imbalance of MMPs and TIMPs system are closely related to the occurrence of ocular diseases, especially ocular surface diseases. It is believed that the excessive expression of MMPs, including MMP-1, MMP-3 and MMP-9 in fibroblasts in conjunctival stroma are key factors to cause imbalance between MMPs and TIMPs. Imbalance between MMPs and TIMPs leads to the melt of collagen fiber, elastic fiber degeneration, excessive degradation of conjunctival matrix and Tenon capsule, causing abnormal ocular surface tears. Ocular surface tear abnormality destroys the stability of the ocular surface environment, involved in many ocular surface diseases such as dry eye, conjunctival relaxation, pterygium, keratitis, and many other pathological changes of ocular surface diseases.  (Int Rev Ophthalmol,  2017,  41:   32-37)