Is Normal Tension Different Than High Tension Glaucoma: Other Possible Factors

Open angle glaucoma (OAG) the second leading cause of irreversible blindness in the United States1, comprises 2 major syndromes: primary open angle glaucoma (POAG) and normal pressure glaucoma (NPG). POAG is a disease generally characterized by a clinical triad which consists of 1) elevated intraocular pressure (IOP); 2) the appearance of optic atrophy presumably resulting from elevated IOP; and 3) a progressive loss of peripheral visual sensitivity in the early stages of the disease, which may ultimately progress and impair central visual acuity2. Primary open angle glaucoma affects approximately 0.5% of the American population3 and occurs in 1.3% of white and 4.7% of black Americans over the age of 40 (1.6 million persons)4. Studies have indicated, however, that a surprisingly high percentage of patients with open-angle glaucoma have findings identical to those of POAG but with a singular exception; namely, that the IOP has never been demonstrated to be elevated. This form of glaucoma is often called lowtension glaucoma, but also goes by the names normal tension and normal pressure glaucoma.