Also, NADPH-diaphorase (NADPH-d) reactivity, a marker for NO production, was decreased in TM, SC, and anterior longitudinal CM fibers isolated from POAG eyes (Nathanson and Mckee, 1995a) and serum levels of L-arginine analogs (endogenous NOS inhibitors) were found to be elevated in patients with advanced glaucoma (Javadiyan et al., 2012). This evidence concerns the gene NOS1 and open-angle glaucoma.