Nocturnal hypotension: role in glaucoma progression.

The role of systemic blood pressure in glaucomatous damage remains undefined, with systemic hypertension and hypotension being implicated in different studies. We have previously reported that the physiologic nocturnal blood pressure "dip" may be exaggerated in some glaucoma patients with progressive field loss. A 24-hour ambulatory blood pressure recording was originally performed on 84 patients with glaucoma. The mean result across all our glaucoma patients were within the ranges reported in the literature for normal subjects. The normal-tension glaucoma and primary open-angle glaucoma groups did not differ significantly in blood pressure variables. Nocturnal blood pressure variables were lower in the patients with progressive field defects compared to those with stable visual fields. To determine long-term outcomes in these patients, we reevaluated the visual fields of the original 84 patients studied. In 70 patients with long-term visual field data (mean, 5.1 years), those who had shown greater nocturnal blood pressure dips were more likely to have shown field progression at some stage, despite good intraocular pressure control. Patients who had field progression showed significantly lower nocturnal blood pressure variables, with the dips of the systolic, diastolic, and mean arterial pressure significantly larger (systolic dip, P = 0.01). They also had a greater history of disk hemorrhages. A review of other 24-hour blood pressure studies in the literature shows that most are in agreement with these findings. The nocturnal reduction in blood pressure may, therefore, be an additional risk factor in glaucoma patients.