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Patients with normal-tension glaucoma (NTG) may have generalized vascular dysregulation, increasing their risk of cardiovascular and cerebrovascular diseases, according to research published in the Journal of Glaucoma. Prior research has linked glaucoma to hypotension and exaggerated nocturnal blood pressure (BP) dipping. However, British researchers have found that a higher proportion of patients with glaucoma had systemic hypertension, blunted nocturnal blood pressure dipping, and a morning BP surge, the report says.
Clinicians can detect the presence of glaucoma by monitoring for raised intraocular pressure (IOP). But, for patients with NTG, factors other than IOP may play a key role in the disease’s pathogenesis, the study states. Examining the relationship between IOP and BP in glaucoma is often complicated by short- and long-term fluctuations in both measurements. While ambulatory blood pressure monitoring (ABPM) is recommended to assess BP and diagnose systemic hypertension, ambulatory IOP monitoring devices have only become available recently and aren’t widely used.
The study included 45 participants with NTG and 10 control patients. Researchers used remote monitoring to examine ambulatory fluctuations in IOP and BP in glaucoma patients. Patients using systemic antihypertensives were excluded from the study. All participants had a comprehensive ophthalmological examination followed by glaucoma medication washout.
IOP and BP were recorded for 48 hours via home monitoring with a self-rebound tonometer and ambulatory blood pressure monitor. BP was recorded every 30 minutes during the day and every 60 minutes overnight. IOP was recorded at 09:00, 11:00, 13:00, 16:00, 20:00, and 04:00. Participants with NTG had a median mean deviation (MD) of -4.66 dB (interquartile range: -7.16 to -2.81 dB) in the worse eye. Among those with glaucoma, 18 of 45 (40%) had normal nocturnal BP dipping, 24 (53%) blunted dipping, and 3 (6.7%) experienced exaggerated dipping. Each 10 mm Hg of lower minimum sleeping systolic BP was associated with approximately 0.9 dB worse MD. Sixteen of 45 participants with glaucoma (35.6%) and 1 of 10 participants in the control group (10%) were found to have systemic hypertension on ABPM and 32 of those with glaucoma (71%) had a surge in morning BP, compared with 5 controls (50%). There was no difference in MD between patients with normal, exaggerated, and blunted dipping (P =.813).
The research concludes that, while the results do not provide enough evidence to warrant universal routine home BP monitoring for glaucoma patients, there may be a role for ABPM in some patients. Patients with progressive visual field loss despite low IOP or symptoms of hypotension may benefit from home monitoring, and the technology may help progressing patients using systemic antihypertensives.
Researchers note several limitations of their study, including the small number of participants in the control group and the significantly younger age of the control group than those with glaucoma. Systemic hypertension is more common in older patients, which might explain the higher prevalence of hypertension in the NTG group. Additionally, the use of a theoretical formula for ocular perfusion pressure calculation may not accurately reflect true ocular perfusion. The lack of examination of the potential impact of patient positioning on BP and IOP was also noted as a limitation. Lastly, ambulatory measurements were only collected for 2 days, and it is possible that monitoring longer may have produced different results.
Disclosure: Several study authors declared affiliations with the pharmaceutical or biotech industries. Please see the original reference for a full list of authors’ disclosures.
Reference
Tan BH, Young A, Bianchi E, et al. Fluctuation in blood pressure and intraocular pressure in normal tension glaucoma using ambulatory monitoring. J Glaucoma. 2021;30(4):304-311. doi:10.1097/IJG.0000000000001768
