Daum 2014.

Methods	Randomised controlled trial, 3 groups, parallel
Participants	51 volunteers who are 40 years of age or older, recruited from the employee population of a call centre, with corrected visual acuity at near (40 cm) of at least 20/40 or better in each eye, at least 0.50D vector dioptric difference in refractive error in their habitual correction in both eyes, stereopsis of at least 40 seconds at 40 cm (corrected, Randot), and use a computer for at least 6 hours per day. Mean age 51.1 years; range: 40 to 65 Male/Female: 2/49 Refractive error: means S−1.32D, C−0.74D, add +1.72D Country: USA
Interventions	Eyeglasses: habitual refractive error (bifocals) vs. fully corrected refractive error (bifocals) vs. Essilor computer glasses.
Outcomes	Post intervention (10 weeks) visual comfort (Convergence Insufficiency Symptom Survey and National Eye Institute Refractive Quality of Life survey) and productivity (productivity in a given day is defined as: Number of calls * Efficiency in answering calls * Accuracy in answering calls * Proportion of time on job) were assessed.
Notes	Data‐extraction based on study protocol and a conference abstract; no full text available.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information on method of randomisation.
Allocation concealment (selection bias)	Unclear risk	No information on method of randomisation.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information on who is masked in what way.
Blinding of outcome assessment (detection bias) Primary outcomes	Unclear risk	No information on who is masked in what way.
Blinding of outcome assessment (detection bias) Secondary outcomes	Unclear risk	No information on who is masked in what way.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information.
Selective reporting (reporting bias)	High risk	There were outcomes reported In the conference abstract that were not in the study protocol.
Other bias	Unclear risk	No information on individual study groups.