Walking for a Short Distance at a Brisk Pace Reduces Intraocular Pressure by a Clinically Significant Amount

Abstract

To determine if walking for a short distance in a natural outdoor setting will have a clinically significant effect on intraocular pressure (IOP). Twenty-five healthy participants (25 eyes) aged 20.8±1.3 years had their IOP measured using noncontact tonometry at baseline, after completing a 1046 m outdoor walking course at a brisk pace and after a 20-minute resting period in a seated position. Repeated-measures analysis of variance was used to compare the average IOP at each time point and Pearson correlation was used to assess relationships between the difference in IOP, baseline IOP, and walking pace. IOP decreased from 16.0±2.6 mm Hg at baseline to 14.6±3.2 mm Hg (-1.4±1.1 mm Hg, P<0.001, 95% confidence interval: +0.7--3.3 mm Hg) after the walk. The IOP remained -0.7 mm Hg below the baseline level (P=0.028, paired t test with Bonferroni correction) after the 20-minute resting period. The decrease in IOP was larger in eyes with a lower baseline IOP (partial Pearson r=0.433, P=0.035, controlled for pace). The average walking pace was 4.7±0.5 km/h and was negatively correlated to the decrease in IOP (partial Pearson r=-0.432, P=0.035, controlled for baseline IOP). The postrest recovery of IOP was greater for participants who demonstrated a greater decrease in IOP during the walking period (Pearson r=-0.427, P=0.033). A short brisk walk caused a clinically significant reduction in IOP by an amount that was related to the relative intensity of the exertion, and it did not recover within a 20-minute period. Clinicians are advised to seek information regarding recent physical activity (including walking) and the subsequent resting period, when highly accurate measurements of IOP are required.