Although controversial, normal-tension glaucoma (NTG) can be considered a subset of open-angle glaucoma (POAG) . Any intraocular pressure cut-off value for NTG is inherently arbitrary since intraocular pressure (IOP) is a continuous risk factor for POAG. Population studies have demonstrated that about 20-30% of patients with POAG have IOP =21 mmHg, except in Japan where the prevalence of NTG is much higher. POAG is a multifactorial disease, and it is highly likely that some of the disease-associated factors are IOP-dependent, and some are not. It follows that in patients with NTG, non-IOP-dependent factors play a substantial contribution in the disease process. For any given patient, the clinical findings and differential diagnosis of POAG and NTG are indistinguishable. The treatment strategies are also similar. Optic disc hemorrhage, lower ocular perfusion pressure, and history of migraine are significant risk factors for disease progression. As demonstrated in the Collaborative Normal- Tension Glaucoma Study (CNTGS) and Early Manifest Glaucoma Trial (EMGT), however, a large proportion of patients with NTG remain stable even without treatment for a period of 5-6 years. Treatment to lower IOP 30% reduces the risk of disease progression by 66%, but observation without treatment may be warranted in some patients with early-stage glaucomatous optic neuropathy.
|Original language||English (US)|
|Title of host publication||Medical Diagnosis and Therapy|
|Number of pages||9|
|State||Published - Jan 1 2015|
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