Glaucoma is one of the most important civilization diseases and leads to irreversible blindness. Inspite of many years of research, the causes of this disorder remain unclear. This disease is extremely difficult to diagnose because its primary phase is asymptomatic. After laborious research it has been discovered that metalloproteinases, i.e. proteolytic enzymes involved in the pathogenesis of many kinds of glaucoma, are crucial in glaucoma diagnosis. The overexpression of matrixins leads to degradation of extracellular matrix components, which results in eye tissue injury and changes of tissue properties. Structural disorders occurring in this way are one of the many key reasons for progressive glaucomatous optic neuropathy. The presence of altered expressions of MMP-1, -2, -3, -7, -9, and -12 and their tissue inhibitors TIMP-1 and -2 in the glaucomatous eye paves new ways for the diagnosis and treatment of open-angle glaucoma. The detection of polymorphisms and mutations in genes encoding these enzymes will allow qualifying a patient to a risk group and people who are already ill may be treated by regulation of metalloproteinases activity. This review focuses on the presence and function of metalloproteinases in open-angle glaucoma and on treatment possibilities through MMP regulation.