Normal-tension glaucoma: is it different from primary open-angle glaucoma?

Normal-tension glaucoma (NTG) is a common form of open-angle glaucoma throughout the world, and yet there are many unanswered questions regarding both the mechanisms of the optic neuropathy and the treatment of these patients. The present review considers how recent literature advances our understanding of both the mechanisms of glaucomatous damage and the treatment of patients with NTG.

The main theme in the current literature continues to be that NTG and primary open-angle glaucoma (POAG) represent a continuum of open-angle glaucomas, in which a certain level of intraocular pressure (IOP) is the predominant causative risk factor in POAG, while additional IOP-independent factors take increasing importance in NTG. There is considerable overlap between the two conditions, however, and within the population of NTG patients there are subsets in which IOP, blood flow and other factors assume relative importance.

In clinical practice, control of IOP remains the mainstay of managing NTG patients, but consideration must also be given to other factors, especially those that may influence perfusion of the optic nerve head. Treatment paradigms will likely change as researchers continue to investigate the mechanisms of glaucomatous optic neuropathy and search for IOP-independent neuroprotective agents.