Clinical update on normal tension glaucoma.

Normal tension glaucoma (NTG) is a common form of open-angle glaucoma that can lead to significant visual morbidity. There has been considerable debate as to whether NTG fits within the spectrum of primary open-angle glaucoma (POAG). The relative roles of intraocular pressure and pressure-independent factors in this disease have also been debated. This review provides an extensive analysis of key clinical features, differential diagnoses, and potential pathophysiologic mechanisms, both intraocular and systemic, of NTG. Findings of major clinical trials and evidence-based guidelines for management are also reviewed.