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 (VIM_MAP). In particular, each 1-standard deviation increase in VIM_MAP 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 VIM_MAP 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.