Effects of laughter exercise on intraocular pressure, Schlemm’s canal and chorioretinal parameters in healthy adults

PURPOSE: This study investigated the effects of laughter exercise on IOP, anterior and posterior segment parameters in healthy adults. METHODS: This study involved 23 healthy adults who underwent baseline and post-intervention measurements of IOP and ocular structures. Using swept-source OCT(SS-OCT), we quantified Schlemm's canal area (SCAR) and trabecular meshwork thickness across four quadrants, and assessed posterior segment parameters with a 24 × 20 mm ultra-widefield protocol. Measurements were repeated at 1, 15, 30, and 60 min after a 5-minute standardized laughter exercise to analyze longitudinal changes and IOP correlations. RESULTS: IOP significantly decreased at 1, 15, and 30 min after laughter exercise (all p < 0.01), then recovered at 60 min(p = 0.131). The nasal SCAR significantly enlarged at 15 min(p < 0.001) and 30 min post-exercise(p = 0.004). Temporal SCAR only showed significant increase at 1 min post-exercise(p = 0.025). The superior SCAR significantly enlarged at 1 min(p = 0.008) and 30 min(p = 0.041) post-exercise. Inferior SCAR remained stable throughout the study period(p = 0.204). The trabecular meshwork thickness in all 4 quadrants only exhibited significant increase at 1 min post-exercise(all p < 0.01). No significant changes in chorioretinal parameters were noted (all p > 0.05). In the multivariate model, retinal superficial capillary plexus vessel density positively corelated with IOP (β=4.00, p = 0.009), whereas nasal SCAR demonstrated a negative correlation (β=-2.40, p = 0.003). CONCLUSIONS: The anterior and posterior segment demonstrated distinct responses to a standardized laughter exercise. The IOP changes are associated with the expansion of Schlemm's canal. Further research is warranted to determine the efficacy of laughter exercise as a non-pharmacological adjunct for IOP control.