PERFORMANCE EVALUATION OF BLUE LIGHT SCREEN PROTECTORS VERSUS BLUE LIGHT SPECTACLE LENSES

Abstract

Background Blue-light filtering products, including screen protectors and spectacle lenses, are widely sold to reduce digital eye strain (DES), but there is little direct evidence comparing the two product types against each other. Objective To compare the blue-light filtering performance and symptom-relief effectiveness of blue-light screen protectors versus blue-light spectacle lenses in reducing digital eye strain among young adult screen users. Methods In this two-phase comparative study, ten commercial screen protectors and ten spectacle lens products were tested in a laboratory experiment measuring blue-light transmittance, followed by a three-group, pre-test/post-test comparative experimental study in which 96 university students aged 18–25 years with symptomatic digital eye strain were divided into three groups of 32 (screen protector, spectacle lens, and control); participants used their assigned product, or no filter for the control group, for 4 weeks, during which digital eye strain symptoms (CVS-Q score) and critical flicker-fusion frequency (CFF) were measured before and after the intervention period, with primary outcomes being the percentage reduction in blue-light transmittance and the change in CVS-Q score and CFF from baseline to 4 weeks; the sample size of 96 participants (32 per group) was calculated using a one-way ANOVA formula (f = 0.35, α = 0.05, power = 80%), allowing for 20% attrition. Results Spectacle lenses showed significantly greater blue-light attenuation than screen protectors in laboratory testing (31.2% vs 19.8%, p < 0.001). Clinically, both the spectacle lens group and the screen protector group showed significantly greater improvement in CVS-Q score than the control group (p < 0.001), with the spectacle lens group improving significantly more than the screen protector group (p = 0.003). Conclusion Blue-light spectacle lenses appear to offer both better optical filtering performance and greater symptom relief than screen protectors, though both outperform no intervention over a 4-week period of regular use.