Influence of Exercise on Intraocular Pressure, Schlemm's Canal, and the Trabecular Meshwork

We aimed to assess the changes in IOP, Schlemm's canal (SC), and the trabecular meshwork (TM) in healthy individuals after exercise.

The area and perimeter of SC, TM thickness, IOP, pupil diameter, blood pressure (BP), heart rate, and plasma catecholamine concentrations were measured in 29 young healthy individuals before and after exercise by jogging for 20 minutes. The TM and SC in the superior, inferior, nasal, and temporal regions were evaluated by 80-MHz ultrasound biomicroscopy.

In comparison with the baseline values, the post-exercise values of IOP had significantly reduced, and those of the pupil diameter, systolic and diastolic BP, and plasma catecholamine concentrations had significantly increased (all, P < 0.05). There were no significant differences in the proportions of eyes with observable SC before (81.9%) and after (90.5%; X = 3.652; P = 0.057) exercise. In comparison with the baseline values, the mean values of area (132.83 ± 19.67 vs. 155.33 ± 21.46 pixels; P < 0.001) and perimeter (54.94 ± 4.95 vs. 60.23 ± 4.19 pixels; P < 0.001) of SC and TM thickness (10.30 ± 1.28 vs. 11.48 ± 1.07 pixels; P < 0.001) after exercise were increased. The increase in area (r = 0.019, P = 0.923) and perimeter (r = -0.109, P = 0.573) of SC and TM thickness (r = -0.088, P = 0.651) were not significantly correlated with the decrease in IOP.

Aerobic exercise could cause sympathetic nerve stimulation, consequently causing the expansion of the TM and SC, which, in turn, leads to IOP reduction. Furthermore, SC and the TM might have an autonomic regulation function, and their expansion and collapse might not be completely dependent on the IOP.