Glaucoma, a potentially blinding eye disorder, is characterized by increased intraocular pressure (IOP), excavation of optic nerve head, and gradual loss of visual field. [ 1 1. (a) Tielsch , JM ; Sommer , A. ; Katz , J. ; Royall , RM ; Quigley , HA ; Javitt , J. Racial variations in the prevalence of primary open-angle glaucoma . Baltimore Eye Survey 1991 , 266 , 369 – 374 ; (b) Quigley , HA Number of people with glaucoma worldwide . Br. J. Ophthalmol. 1991 , 80 , 389 – 393 ; (c) Quigley ...