The short-term influence of exercise on axial length and intraocular pressure

Purpose The aim of this study is to investigate the short-term influence of a period of dynamic exercise on axial length (AXL) and intraocular pressure (IOP) in young adult subjects. Patients and methods In all, 20 young adult subjects (10 myopes and 10 emmetropes) participated. Baseline measures of ocular biometrics, IOP and ocular pulse amplitude (OPA) were taken following a 20-min rest period. Subjects then performed 10 min of moderate intensity, low impact dynamic exercise (bicycle ergometry). Measures of ocular biometrics, IOP and OPA were repeated immediately after, and then 5 and 10 min after this exercise task. Systemic blood pressure and pulse rate were also monitored. A repeated measures analysis of variance was used to investigate the changes in the measured parameters. Results Exercise resulted in significant changes in a range of ocular parameters. A small but significant decrease in AXL was observed following exercise (P < 0.0001). The largest change in AXL was noted immediately following exercise (mean decrease -17 +/- 10 mu m). IOP and OPA also decreased significantly following exercise (P < 0.0001). A moderate but significant positive association was found between the changes in AXL and the changes in IOP (r(2) = 0.36, P < 0.0001). There were no significant differences found between the myopic and emmetropic subjects in the magnitude of changes observed in ocular parameters following exercise. Conclusion The physiological effects of dynamic exercise lead to changes in a range of ocular parameters, including significant reductions in IOP, OPA and decreases in AXL. Eye (2011) 25, 767-774; doi:10.1038/eye.2011.54; published online 18 March 2011