Effects of anti-fatigue lenses on performance, muscle activity and subjective discomfort responses during a seated...

Anti-fatigue lenses (AFL) intend to provide health benefits in association with computer work. Their effects on visual and muscle discomfort mechanisms and task performance remain unclear. Twenty-three computer users (n = 12 males) underwent two 90-min computer sessions with AFL or placebo lenses. Eye strain, body discomfort, typing performance, upper trapezius (UT) activation amplitude and variability, and neck posture were analyzed for time, condition, and sex effects. No significant effects of condition were observed on the dependent measures evaluated. Discomfort increased over time (neck/shoulder: p < .001), more so in females (eye strain: p < .001). Females' UT activation amplitude was negatively correlated to eye strain in the placebo condition (p = .05).