Real-world assessment of physical activity in glaucoma using an accelerometer

Abstract

Objective: To determine the association between glaucomatous visual field (VF) loss and the amount of physical activity and walking in normal life.

Design: Prospective, observational study.

Participants: Glaucoma suspects without significant VF or visual acuity loss (controls) and glaucoma subjects with bilateral VF loss between 60 and 80 years of age.

Methods: Participants wore an accelerometer over 7 days of normal activity.

Main outcome measures: Daily minutes of moderate or vigorous physical activity (MVPA) was the primary measure. Steps per day was a secondary measure.

Results: Fifty-eight controls and 83 glaucoma subjects provided sufficient study days for analysis. Control and glaucoma subjects were similar in age, race, gender, employment status, cognitive ability, and comorbid illness (P>0.1 for all). Better-eye VF mean deviation (MD) averaged 0.0 decibels (dB) in controls and -11.1 dB in glaucoma subjects. The median control subject engaged in 16.1 minutes of MVPA daily and walked 5891 steps/day, as compared with 12.9 minutes of MVPA daily (P = 0.25) and 5004 steps/day (P = 0.05) for the median glaucoma subject. In multivariate models, glaucoma was associated with 21% less MVPA (95% confidence interval [CI], -53% to 32%; P = 0.37) and 12% fewer steps per day (95% CI, -22% to 9%; P = 0.21) than controls, although differences were not statistically significant. There was a significant dose response relating VF loss to decreased activity, with each 5 dB decrement in the better-eye VF associated with 17% less MVPA (95% CI, -30% to -2%; P = 0.03) and 10% fewer steps per day (95% CI, -16% to -5%; P = 0.001). Glaucoma subjects in the most severe tertile of VF damage (better-eye VF MD worse than -13.5 dB) engaged in 66% less MVPA than controls (95% CI, -82% to -37%; P = 0.001) and took 31% fewer steps per day (95% CI, -44% to -15%; P = 0.001). Other significant predictors of decreased physical activity included older age, comorbid illness, depressive symptoms, and higher body mass index.

Conclusions: Overall, no significant difference in physical activity was found between individuals with and without glaucoma, although substantial reductions in physical activity and walking were noted with greater levels of VF loss. Further study is needed to characterize better the relationship between glaucoma and physical activity.

Financial disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Figure 1

Daily walking and physical activity by glaucoma status Severe glaucoma groups includes those with better eye visual field scores in the lowest tertile, corresponding to a better eye visual field mean deviation worse than -13.5 decibels.

Figure 2

Lowess plot of Daily Step Counts by Extent of Better-Eye Visual Field Loss MD = Mean deviation; dB = decibels

Figure 3

Likelihood of meeting various step targets by glaucoma status Severe glaucoma group includes subjects in the tertile of most severe glaucoma (better eye visual field mean deviation worse than -13.5 decibels).