Normal-tension glaucoma: an update / Glaucoma de pressão normal: atualização

ABSTRACT Normal-tension glaucoma (NTG) is a progressive optic neuropathy with intraocular pressure (IOP) within the statistically normal range (≤21 mmHg). The prevalence of NTG varies widely among different population studies, being the most prevalent open-angle glaucoma subtype in some reports. The etiology of NTG possibly is multifactorial and still not well defined. Alternative treatments have been proposed based on pathogenesis details. However, in clinical practice, adequate reduction of IOP remains the keystone of managing patients with NTG. We review the pathogenesis of NTG and the available therapies for this optic neuropathy.

RESUMO O glaucoma de pressão normal (GPN) é uma neuropatia óptica progressiva que cursa com a pressão intraocular (PIO) dentro da faixa de normalidade (≤21 mmHg). A prevalência do glaucoma de pressão normal varia entre os estudos populacionais, sendo em alguns o principal subtipo de glaucoma primário de ângulo aberto. A etiologia do glaucoma de pressão normal possivelmente é multifatorial e ainda não foi totalmente esclarecida. Tratamentos alternativos baseados nos diferentes detalhes da patogenia foram recentemente propostos. Entretanto, na prática clínica, a redução adequada da pressão intraocular continua sendo a base do tratamento do glaucoma de pressão normal. O objetivo deste artigo é revisar a patogênese do glaucoma de pressão normal e as formas de terapia disponíveis.

Normal-tension glaucoma (Low-tension glaucoma).

Glaucoma is now considered an abnormal physiology in the optic nerve head that interacts with the level of intraocular pressure (IOP), with the degree and rate of damage depending on the IOP and presumably the degree of abnormal physiology. Diagnosis of normal-tension glaucoma (NTG), defined as glaucoma without a clearly abnormal IOP, depends on recognizing symptoms and signs associated with optic nerve vulnerability, in addition to absence of other explanations for disc abnormality and visual field loss. Among the findings are a halo or crescent of absence of retinal pigment epithelium around the disc, bilateral pre-chiasmal visual field defects, splinter hemorrhages at the disc margin, vascular dysregulation (low blood pressure, cold hands and feet, migraine headache with aura, and the like), or a family history of glaucoma. Possibly relevant, is a history of hemodynamic crisis, arterial obstructive disease, or sleep apnea. Neurological evaluation with imaging is needed only for atypical cases or ones that progress unexpectedly. Management follows the same principle of other chronic glaucomas, to lower the IOP by a substantial amount, enough to prevent disabling visual loss. However, many NTG cases are non-progressive. Therefore, it may often be wisein mild cases to determine whether the case is progressive and the rate of progression before deciding on how aggressivene to be with therapy. Efforts at neuroprotection and improvement in blood flow have not yet been shown effective.