LAUSR

PURPOSE To investigate if blue-blocking lenses are effective in reducing the ocular signs and symptoms of eye strain associated with computer use. DESIGN Double-masked, randomized controlled trial. METHODS 120 symptomatic computer users were randomly assigned (1:1) into a 'positive' or 'negative' advocacy arm (i.e., a clinician either advocating, or not advocating, for the intervention via a pre-recorded video). Participants were further sub-randomized (1:1) to receive either clear (placebo) or blue-blocking spectacles. All participants were led to believe they had received an active intervention. Participants performed a two-hour computer task whilst wearing their assigned spectacle intervention. The pre-specified primary outcome measures were the mean change (post- minus pre-computer task) in eye strain symptom score and critical flicker-fusion frequency (CFF, an objective measure of eye strain). The study also investigated whether clinician advocacy of the intervention (in a positive or negative light) modulated clinical outcomes. RESULTS All participants completed the study. In the primary analysis, for CFF, no significant effect was found for advocacy type (positive or negative, p=0.164) and spectacle intervention type (blue-blocking or clear lens, p=0.304). Likewise, for eye strain symptom score, no differences were found for advocacy (p=0.410) or spectacle lens types (p=0.394). No adverse events were documented. CONCLUSIONS Blue-blocking lenses did not alter signs or symptoms of eye strain with computer use relative to standard clear lenses. Clinician advocacy type had no bearing on clinical outcomes. ABBREVIATIONS AND ACRONYMS CVS = computer vision syndrome; RCT = randomized controlled trial; CFF = critical flicker-fusion frequency; SD = standard deviation; IQR = inter quartile range; ANOVA = analysis of variance.