This randomized controlled study aims to investigate the acute effects of a single session of web-based visual training on balance, reaction time, and cognitive function in professional e-sports players. Participants will be randomly assigned to either a web-based visual training group or a control group. The intervention group will receive a single approximately 25-minute session including eye relaxation, eye movement exercises, convergence-divergence, accommodation, figure-ground perception, and visual attention exercises. The control group will receive no intervention. Balance, reaction time, and cognitive function will be assessed at baseline and immediately after the intervention.