Myocilin (MYOC),also known as TIGR or GLC1A,is a secreted glycoprotein of the olfactomedin family,originally identified in trabecular meshwork cells after prolonged treatment with glucocorticoids,and,independently,in the retina . It may participate in the obstruction of fluid outflow in the trabecular meshwork. Defects in MYOC are the cause of primary open angle glaucoma (POAG) .