Normal tension glaucoma is an optic neuropathy in which the retinal nerve fiber layer thickness is reduced, the optic nerve is pathologically excavated, and the visual field is disturbed, although intraocular pressure is classified as normal. Patients with normal tension glaucoma are a heterogeneous group in which many systemic pathologic conditions may be present, and presenting ocular clinical signs that are difficult to be identified in the early stages of the disease. Treatment is more challenging than in hypertensive glaucomas. The authors sought to review the pathophysiology and differential diagnosis of this condition assessing vascular, rheumatic, neurological and genetic aspects that should be studied, as well as its treatment. The sources of references are PubMed (MEDLINE), LILACS and Cochrane Library (CENTRAL) databases.