Spectacle interventions for treating eye strain with computer use

Description of interventions (prior to publication of the study findings) - as per original registry entry details: 1. The subjects will be randomised to one of four spectacle lenses of different brands. Intervention 1 – spectacle lens brand 1; intervention 2 – spectacle lens brand 2; intervention 3 – spectacle lens brand 3; intervention 4 – spectacle lens brand 4. 2. For the purposes of the study, “laboratory conditions” denotes the running of the experiment within a designated research laboratory space, in which critical aspects of the tasks (e.g. equipment, light levels, absence of other distractions) are well-controlled environment, and run according to a standardized procedure. 3. Participants will be advised to wear spectacle lenses for a total duration of 2-hours whilst performing the computer task, which involves transcribing numbers from a PDF document into a spreadsheet and identifying data entry errors from a document presented on a computer screen. Description of interventions (submitted as private notes in the original registration process, but now being entered into the public domain, further to publication of the study findings): In this study, we sought to quantify the magnitude of how much practitioner advocacy can augment the response of patients to blue light filtering spectacle interventions, in patients who believe they have been administered the intervention. Our study contains a placebo treatment (i.e. conventional non blue light filtering spectacle lenses not designed to alleviate CVS), but all patients will be led to believe they have received an active treatment. The nature of this deception is therefore not described in the publicly visible documentation for the study, to prevent this deception being unmasked. In both the treatment and placebo groups, half of participants will be instructed (using a standardized script) that there is strong clinical impression that the treatment is effective, whereas the other half will be instructed that there is a strong clinical impression that the treatment is not effective. Our study design therefore allows us to simultaneously measure treatment effects (i.e. overall difference between treatment and placebo arm) as well as how practitioner advocacy influences CVS outcomes in patients who believe they have received a treatment (i.e. overall difference between advocacy verses non-advocacy arms). For the intervention group “Essilor Prevencia” blue light filtering lenses will be used, and for the control group non-blue light filtering spectacle lenses with a conventional anti reflection coating will be used. So, the 4 intervention arms comprise: 1. Blue-light filtering lenses + positive clinician advocacy 2. Blue-light filtering lenses + negative clinician advocacy 3. Non blue-light filtering lenses (control) + positive clinician advocacy 4. Non blue-light filtering lenses (control) + negative clinician advocacy