Physical Activity Is Associated With Macular Thickness: A Multi-Cohort Observational Study

Abstract

Purpose: To assess the association between physical activity and spectral-domain optical coherence tomography (SD-OCT)-measured rates of macular thinning in an adult population with primary open-angle glaucoma.

Methods: The correlation between accelerometer-measured physical activity and rates of macular ganglion cell-inner plexiform layer (GCIPL) thinning was measured in 735 eyes from 388 participants of the Progression Risk of Glaucoma: RElevant SNPs with Significant Association (PROGRESSA) study. The association between accelerometer-measured physical activity and cross-sectional SD-OCT macular thickness was then assessed in 8862 eyes from 6152 participants available for analysis in the UK Biobank who had SD-OCT, ophthalmic, comorbidity, and demographic data.

Results: Greater physical activity was associated with slower rates of macular GCIPL thinning in the PROGRESSA study (beta = 0.07 µm/y/SD; 95% confidence interval [CI], 0.03-0.13; P = 0.003) after adjustment for ophthalmic, demographic and systemic predictors of macular thinning. This association persisted in subanalyses of participants characterized as glaucoma suspects (beta = 0.09 µm/y/SD; 95% CI, 0.03-0.15; P = 0.005). Participants in the upper tertile (greater than 10,524 steps/d) exhibited a 0.22-µm/y slower rate of macular GCIPL thinning than participants in the lower tertile (fewer than 6925 steps/d): -0.40 ± 0.46 µm/y versus -0.62 ± 0.55 µm/y (P = 0.003). Both time spent doing moderate/vigorous activity and mean daily active calories were positively correlated with rate of macular GCIPL thinning (moderate/vigorous activity: beta = 0.06 µm/y/SD; 95% CI, 0.01-0.105; P = 0.018; active calories: beta = 0.06 µm/y/SD; 95% CI, 0.006-0.114; P = 0.032). Analysis among 8862 eyes from the UK Biobank revealed a positive association between physical activity and cross-sectional total macular thickness (beta = 0.8 µm/SD; 95% CI, 0.47-1.14; P < 0.001).

Conclusions: These results highlight the potential neuroprotective benefits of exercise on the human retina.

Figure 1.

Study cohort schematic. (A) In this study, 465 participants in the PROGRESSA cohort successfully completed the 7-day study period. Following review of SD-OCT imaging, the rates of macular GCIPL thinning were correlated with recorded mean daily steps in 735 eyes from 388 participants. (B) In the secondary analysis, 96,679 participants of the UK Biobank successfully completed the physical activity study. Of the potential 193,358 eyes of this cohort, 11,051 eyes had available macular thickness data. A further 2189 eyes (n = 1547 participants) were then excluded due to unavailable comorbidity or demographic data, leaving 8862 eyes from 6152 participants for analysis.

Figure 2.

Correlation between mean daily step count and rate of macular thinning in the PROGRESSA cohort and physical activity and macular thickness in the UK Biobank cohort. (A) Scatterplot depicting the association between mean daily step count (x-axis) and rate of change in macular thickness (y-axis). The blue line indicates the linear regression between step count and rate of macular thinning with 95% confidence intervals (gray shaded area). The dashed line is representative of a rate of change of 0 µm/y. In the PROGRESSA cohort, a higher daily step count was correlated with a slower rate of macular GCIPL thinning. The P value was derived from multivariable analysis. (B) Scatterplot depicting the association between physical activity (x-axis) and total macular thickness in the UK Biobank (y-axis). The blue line indicates the linear regression between standardized physical activity and total macular thickness with 95% confidence intervals (gray shaded area). In the UK Biobank, greater physical activity was associated with greater total macular thickness after adjustment for age, gender, and associated ocular and systemic predictors of macular thickness. The P value was derived from multivariable analysis.