Purpose: Real-world physical activity patterns in monocular persons have not been previously characterized. This study uses a nationally representative sample to compare the physical activity levels of functionally monocular to binocularly sighted persons in the United States.
Methods: This cross-sectional study uses data from the 2003-2004 and 2005-2006 National Health and Nutrition Examination Survey (NHANES) to compare differences in physical activity between functionally monocular and binocular participants. The main outcome measures were accelerometer-measured mean steps per day and mean daily minutes of moderate or vigorous physical activity (MVPA). Statistical analysis was conducted using multivariable negative binomial regression models adjusted for age.
Results: In total, 7967 NHANES participants had complete visual acuity and accelerometer data. The mean age at baseline was 44.5 years, and a majority were Caucasian (73%) and female (51%). In models adjusted for age only, functionally monocular participants (n = 172) took fewer steps (9277 with 95% confidence interval [CI], 8800-9753 vs. 10,057 with 95% CI, 9832-10,281) and engaged in similar minutes of MVPA (26.75 with 95% CI, 22.0-31.5 vs. 26.70 with 95% CI, 25.6-27.7) per day compared to binocularly sighted participants (n = 7758). In our final model, functionally monocular participants took 16% fewer steps per day (P < 0.01) and engaged in 26% fewer minutes per day of MVPA (P = 0.01). Poorer visual acuity, older age, female gender, obesity, congestive heart failure, and arthritis were also associated with a statistically significant decrease in physical activity in both models.
Conclusions: Functionally monocular persons have lower physical activity levels compared to those with binocular eyesight in the United States, even after adjusting for better-eye visual acuity.
Translational relevance: Our translational study provides insight into the epidemiology of physical activity and its impact on population health. We quantify real-world physical activity in two at-risk populations, monocular and blind individuals.