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Nonlinear Relationship Between Blood Pressure and Glaucoma in US Adults

BACKGROUND
Previous studies have reported that vascular disease is associated with glaucoma. However, the relationship between blood pressure (BP) and glaucoma has been inconsistent. We investigated whether there is a nonlinear association between BP and glaucoma in an adult population of the United States.


METHODS
From the 2005-2008 National Health and Nutrition Examination Survey data, 4,137 participants aged 40 years and older were chosen. BP was assessed based on a standard protocol. Glaucoma was determined using fundus photographs. Age, sex, race/ethnicity, education, poverty, antihypertensive medication, and history of cardiovascular disease were also considered in analyses.


RESULTS
The prevalence of glaucoma was 1.2%. In the multivariate analysis, both high (≥161 mm Hg) and low (≤110 mm Hg) levels of systolic BP were found to be positively associated with glaucoma in those without antihypertensive medications: their prevalence ratios (95% confidence intervals) for glaucoma were 6.42 (1.01-40.81) and 5.46 (1.77-16.53), respectively, when compared to the reference levels of systolic BP (111-120 mm Hg). Also, both high (≥91 mm Hg) and low (≤60 mm Hg) levels of diastolic BP were positively associated with glaucoma in those without antihypertensive medications. The prevalence of glaucoma was lowest in those having systolic BP levels of 111-120 mm Hg and diastolic BP levels of 81-90 mm Hg. However, there were no such U-shaped relationships in those with antihypertensive medications.


CONCLUSIONS
There was a nonlinear (U-shaped) relationship between BP and the glaucoma in those without antihypertensive medications. Future longitudinal studies are warranted to confirm our findings, including the optimal BP levels for the prevention of glaucoma.