Low cardiorespiratory fitness is associated with elevated intraocular pressure among apparently healthy adults

Purpose To evaluate the association of cardiorespiratory fitness with elevated intraocular pressure (IOP) in healthy adults. Methods In this cross-sectional study, we evaluated 17,990 asymptomatic self-referred adults free of diabetes or cardiovascular disease who were screened in a preventive healthcare setting. All subjects underwent measurement of IOP and completed a maximal exercise stress test according to the Bruce protocol. Fitness was categorized into age and sex-specific quintiles according to the treadmill time and dichotomized to low (lowest quintile) and non-low fitness groups. Elevated IOP was defined as ≥ 21 mmHg. Results Median age was 45 (IQR 39–52) years and 12,073 (67%) were men. There were 3,351 (19%) subjects in the low fitness group. Median IOP was 14 mmHg (IQR 12–16) with elevated IOP documented in 188 (1%) subjects. Univariate binary logistic regression model demonstrated that compared with non-low fitness group, subjects in the low fitness group were 2.2 times more likely to have elevated IOP (95% CI 1.598–2.95, p<0.001). Multivariate binary logistic regression with adjustment to known cardiovascular risk factors (age, sex, hypertension, smoking, overweight, regular physical activity, low HDL cholesterol, high triglycerides, and fasting glucose levels) successfully demonstrated that lower fitness was independently and significantly associated with a 90% increased likelihood of elevated IOP (95% CI 1.37–2.61, p<0.001). Subgroup analysis revealed that the association was more pronounced among women compared with men (OR 3.8 vs. 1.6, p for interaction = 0.069). Conclusions Low cardiorespiratory fitness is independently associated with increased IOP among apparently healthy adults.