Nocturnal hypotension linked to glaucoma progression

The results of this prospective study suggest that the duration and magnitude of decrease in nocturnal blood pressure below the daytime mean arterial pressure (MAP), especially pressures that are 10 mmHg lower than daytime MAP, predict normal-tension glaucoma (NTG) progression.

This study investigated whether NTG patients were likely to develop progressive field loss as a result of nocturnal systemic hypotension.

Subjects were 85 NTG patients (166 eyes) with at least five prior visual field tests. They underwent blood pressure monitoring every 30 minutes for 48 hours with an ambulatory recording device at baseline and at six and 12 months.

During the 36 months before study enrollment, 29% showed visual field loss. Multivariate analysis showed that the total time nocturnal sleep MAP was 10 mmHg below daytime MAP was a significant predictor of subsequent visual field progression (P < 0.02).

These results, the authors write, suggest that perhaps all patients who have NTG and are taking anti-hypertensive medications need nocturnal blood pressure monitoring to exclude a deleterious drop in blood pressure. Sleeping with the upper torso elevated, as is done in cardiac patients, may help to limit the fall in blood pressure and subsequent ischemia to the optic nerve.

The authors conclude that randomized trials will be required to assess the efficacy of different interventions designed to avoid nocturnal hypotension to prevent visual field loss in patients with NTG, as well as to test the effect of more aggressive IOP-lowering therapy in these cases.