Physical activity has gotten increasing attention as a lifestyle method which may protect against glaucoma damage. Data supporting this idea come from several sources: animal work showing less ganglion cell damage in mice forced to exercise, a few longitudinal studies (most of which evaluate either physical activity and/or glaucoma through self-report), and cross-sectional analyses showing less physical activity in persons with glaucoma. Yuan and colleagues use the UK Biobank data set to provide further evidence supporting this cross-sectional association. Specifically, they find modest associations between self-reported glaucoma and less time spent in moderate/vigorous physical activity (5% lower in adjusted analyses). In a sub-analysis looking at individuals who were diagnosed with glaucoma over 20 years ago and are thus more likely to have more severe disease, the association was stronger (14% less activity), but not statistically significant after Bonferroni correction.
unclear whether physical activity patterns influenced the onset and progression of glaucoma, glaucoma damage led to activity restriction, or both
They also find more significant reductions in activity over evening hours. Strengths of the article are that it is derived from a large data set which is likely to reflect the UK population well and that glaucoma diagnosis, while obtained through self-report, was verified by records review. One limitation of the study is that disease severity (do one or both eyes have damage?, how much visual field loss is there?) is unknown, such that we can't verify a dose-response relationship between activity levels and disease severity. Indeed, the magnitude of the association observed is small compared to prior studies, perhaps reflecting the inclusion of many mild glaucoma cases, and perhaps even preperimetric cases or suspect glaucoma as visual fields were not reviewed. Also, as the authors acknowledge, the cross-sectional nature of the study leaves it unclear whether physical activity patterns influenced the onset and progression of glaucoma, glaucoma damage led to activity restriction, or both ‐ issues we hope will be addressed by future longitudinal studies or clinical trials.