Nocturnal BP Patterns That May Signal Glaucoma in Hispanics
Ophthalmology, June 2018
Melgarejo et al. observed nocturnal blood pressure (BP) readings from Hispanic patients to identify characteristics that may increase the risk of glaucomatous damage. They found that episodes of extreme reduction in blood pressure (“BP dipping”) are more worrisome than generally low BP itself during the night.
This observational study included 93 participants of the Maracaibo Aging Study who had normal intraocular pressure (IOP) and were at least 40 years old (mean, 62 years). They were required to have undergone optical coherence tomography scanning, visual field (VF) tests, and 24-hour and office BP monitoring. Approximately 14% of the study population had diabetes. Based on results of office and ambulatory BP monitoring, the prevalence of hypertension was 65% and 56%, respectively; and 47% of those with office-identified hypertension were taking antihypertensive medications.
The authors used univariate and multivariate logistic regression analyses to observe relationships between glaucomatous damage and BP parameters, with particular emphasis on nocturnal BP levels. The main outcome measure was glaucomatous optic neuropathy (GON), denoted by the presence of optic nerve damage and VF defects.
Of the 185 eyes evaluated, 49 had signs of GON. It was determined, via gonioscopy, that all GON cases in this study were open angle. Patients with GON had significantly lower nighttime and 24-hour diastolic BP than did those without this neuropathy (p = .009 and .014, respectively). However, the multivariate models with generalized estimating equations suggested that the glaucomatous damage was unrelated to average systolic or diastolic BP measured at daytime, at nighttime, or over 24 hours. Overall, extreme nocturnal drops (>20% compared with daytime BP) in systolic or diastolic BP were significant risk factors for glaucomatous damage (odds ratios: systolic, 19.78; diastolic, 5.55).
This research supports the use of ambulatory 24-hour BP monitoring to help identify individuals with extreme BP dips who require further ophthalmologic assessment. Additional studies of nocturnal BP decreases in people at risk of glaucoma are warranted to clarify the utility of “extreme dipper” status as a risk factor. Therapies that modify glaucoma risk are urgently needed, as are new approaches to avoid extreme dipping, which may include changing the time that antihypertensive drugs are administered.
The original article can be found here.