NOCTURNAL ARTERIAL-HYPOTENSION AND ITS ROLE IN OPTIC-NERVE HEAD AND OCULAR ISCHEMIC DISORDERS

We measured 24-hour ambulatory blood pressure monitoring and diurnal c urve of the intraocular pressure in 166 white patients with anterior i schemic optic neuropathy, normal-tension glaucoma, primary open-angle glaucoma, and other optic nerve head disorders. Hourly average blood p ressure data analyses showed a significant (P < .0001) decrease in mea n systolic (26%) and diastolic (33%) blood pressure measurements at ni ght. A significantly (P = .0028) lower nighttime mean diastolic blood pressure and a significantly (P = .0044) greater mean percentage decre ase in diastolic blood pressure were noted in normal-tension glaucoma than in anterior ischemic optic neuropathy. Patients with arterial hyp ertension taking oral hypotensive therapy showed a significant associa tion between progressive visual field deterioration and nocturnal hypo tension, particularly in anterior ischemic optic neuropathy. Intraocul ar pressure showed no significant correlation with visual field deteri oration in any of these conditions. Our findings suggest that nocturna l hypotension, in the presence of other vascular risk factors, may red uce the optic nerve head blood flow below a critical level, and thereb y may play a role in the pathogenesis of anterior ischemic optic neuro pathy and glaucomatous optic neuropathy; that is, nocturnal hypotensio n may be the final insult in a multifactorial situation. The same mech anisms may be true of a number of other ocular ischemic disorders. Thi s finding opens a new dimension in the understanding and management of these visually disabling diseases.