Higher BP variability tied to normal-tension glaucomatous optic neuropathy
Blood pressure (BP) variability is associated with normal-tension glaucomatous optic neuropathy (GON) via the hypoperfusion of the optic nerve, a recent study has found.
The researchers conducted a cross-sectional analysis of 93 adults (mean age 61.9±12.9 years, 87.1 percent women) who underwent visual field assessments, optical coherence tomography, and 24-hour ambulatory BP monitoring. Twenty-six participants had normal-tension GON, as confirmed by measurements of the retinal nerve fibre layer thickness.
Multivariable-adjusted logistic regression analysis revealed that the risk of GON was significantly correlated with BP variability, as expressed by the variability independent of the mean arterial pressure (VIMMAP). In particular, each 1-standard deviation increase in VIMMAP correlated with a more than twofold increase in the odds of overall GON (odds ratio [OR], 2.17, 95 percent confidence interval [CI], 1.33–3.53; p=0.002).
Similar effects were reported when looking at the risk of GON with (OR, 2.30, 95 percent CI, 1.24–4.30; p=0.009) or without (OR, 2.03, 95 percent CI, 1.17–3.51; p=0.012) visual defects.
Complete adjustment for 24-hour MAP and propensity score only slightly weakened the magnitude of interaction between VIMMAP and overall GON and did not attenuate its significance (OR, 1.93, 95 percent CI, 1.10–3.41; p=0.024). The same was true for GON with visual field defects (OR, 2.30, 95 percent CI, 1.07–4.90; p=0.032). On the other hand, the association with GON without such defects was attenuated (OR, 1.80, 95 percent CI, 0.96–3.32; p=0.067).
“The key finding of our study was that the risk of normal-tension GON increased with higher reading-to-reading VIM of the 24-hour MAP and that this association was independent of the 24-hour MAP level and other confounders summarized in a propensity score,” the researchers said.