Glaucoma Presence and Nocturnal Elevation of Systolic BP
Ophthalmology, October 2019
Although research has revealed links between glaucoma progression and the variability of circadian blood pressure (BP), it is unclear whether glaucoma itself is associated with particular patterns in nighttime BP. Moreover, it can be difficult to recruit healthy subjects for comparison studies. In an observational study, Yoshikawa et al. looked at BP patterns in patients with glaucoma and more than 700 healthy controls. They noted a significant relationship between glaucoma and elevated nighttime BP as well as nondipper status (minimal nocturnal BP reduction). This association was independent of factors such as obesity, diabetes, and older age.
This cross-sectional study included 109 patients with glaucoma and 708 healthy controls. The mean age of both cohorts was 71 years. All study participants underwent ophthalmic examinations, and ambulatory BP was measured every 30 minutes for 48 hours. The nondipper pattern of BP was defined as a decline in mean nighttime systolic BP of <10% of the mean daytime systolic BP.
Daytime and nighttime periods for each participant were determined from entries in sleep diaries.
After adjustment for potential confounders (including age, weight, and concurrent diabetes), multivariable linear regression analyses showed that nocturnal systolic BP was 4.1 mm Hg higher in the glaucoma group (p = .01), and the nondipper pattern was more prevalent in these patients (45.0 vs. 27.5%; p < .001). Similarly, multivariable logistic regression demonstrated that glaucoma increased the likelihood of nondipper status (odds ratio, 1.96; p = .003).
Mechanisms for the low variability of circadian BP in patients with glaucoma may relate to death of the intrinsically photosensitive retinal ganglion cells. Research indicates that the light exposure received by these cells, especially short-wavelength light, is a key contributor to circadian biological rhythm. Furthermore, it is possible that high epinephrine and low melatonin levels could induce circadian misalignment. Nuclear cataracts also have been implicated.
The authors acknowledged that large longitudinal studies are needed to refine potential relationships between nocturnal BP and the severity and progression of glaucoma.
The original article can be found here.