Researchers recently used ambulatory blood pressure (BP) monitoring to determine that normal-tension glaucoma (NTG) patients may experience a BP surge in the morning and blunted nocturnal dipping. These occurrences are associated with generalized vascular dysregulation, and glaucoma has been linked to exaggerated nocturnal BP dipping.

The study included 45 participants with NTG and 10 controls. All participants had a comprehensive ophthalmological examination followed by glaucoma medication washout. Patients recorded IOP and BP at home over 48 hours using a self-rebound tonometer and ambulatory BP monitor. BP was recorded every 30 minutes during the day and every 60 minutes at night. IOP was recorded five times during the day and once in the early morning.

NTG patients had a median mean deviation (MD) of -4.66 dB in the worse eye. Among participants with glaucoma, 40% had normal nocturnal BP dipping, 53% blunted dipping and 7% exaggerated dipping. Each 10mm Hg lower minimum sleeping systolic BP was associated with a 0.9dB worse MD.

The study noted that 36% of participants with glaucoma and 10% of controls had systemic hypertension on ambulatory BP monitoring, and 32 of those with glaucoma (71%) had a surge in morning BP compared with five controls (50%). There was no difference in MD between patients with normal, exaggerated or blunted dipping.

The researchers found the lack of an association between glaucoma and exaggerated nocturnal BP dipping surprising, but they surmised it might be due to the high proportion of patients with undiagnosed systemic hypertension. They also weren’t able to find an association between ambulatory BP monitor measurements and glaucoma severity. However, they suggested that they did not attempt to target patients for inclusion who may have had more BP abnormalities, in whom this form of monitoring may be more likely to detect dipping.

“There may be a role for ambulatory BP monitoring in selected patients, for example, those with progressive visual field loss despite low IOP, those with symptoms of hypotension and in progressing patients using systemic antihypertensives,” the investigators concluded in their paper.

Tan BH, Young A, Bianchi E, et al. Fluctuation in blood pressure and intraocular pressure in normal-tension glaucoma using ambulatory monitoring. J Glaucoma. December 29, 2020. [Epub ahead of print].