Kokke 2008.

Methods	Study design: randomized, parallel‐group, controlled trial Study site(s): not reported if single‐ or multi‐center Number randomized (total and per group): 76 participants; 38 participants randomized to each intervention group (personal communication) Unit of randomization (individual or eye): individual Exclusions after randomization: 26 participants discontinued Losses to follow‐up: none Number analyzed (total and per group): 52 participants in total; 28 participants in the fatty acid treatment group; 24 participants in the control group Unit of analysis (individual or eye): individual (average of both eyes) (personal communication) Reported power calculation? (Y/N): N Reported subgroup analysis? (Y/N): N
Participants	Baseline characteristics Country: United Kingdom Age (mean ± SD, range): 46.4 ± 12.6 years in the fatty acid treatment group; 37.3± 10.7 years in the control group Gender: 76 women Inclusion criteria: 1. Contact lens wearer 2. McMonnies dry eye history questionnaire indicating that they were suffering from dry eye or borderline dry eye (McMonnies score ≥ 10), or that they were experiencing symptoms of contact lens‐induced dry eye Exclusion criteria: not reported Equivalence of baseline characteristics? (Y/N): Y
Interventions	Intervention #1 (treatment group): oral capsule containing evening primrose oil (linoleic acid about 57 mg and γ‐linolenic acid 50 mg, Equazen UK Ltd.), 6 capsules daily (daily dose of linoleic acid about 342 mg and γ‐linolenic acid 300 mg) Intervention #2 (control group): placebo capsule containing olive oil (Equazen UK Ltd.), 6 capsules daily (dose note reported) Length of follow‐up: 6 months Notes: participants were instructed not to change their diet and not to take any additional dietary supplements for the duration of the study
Outcomes	Primary and secondary outcome measures were not clearly distinguished Specified outcome(s): symptoms of dry eye and contact lens discomfort, tear meniscus height, corneal and conjunctival fluorescein staining, corneal and conjunctival rose bengal staining, meibomian gland assessment, lipid layer thickness and quality, TBUT (both non‐invasive with the Tearscope and with fluorescein) and ocular hyperemia; all outcomes were reported as data at study endpoint Adverse events reported? (Y/N): N Measurement time points (specify intervals at which outcomes were assessed): baseline, months 3 and 6 Other issues with outcome assessment (eg, quality control for outcomes, if any): none
Notes	Study dates: not reported Funding source(s): treatment and placebo formulations were provided by Equazen Ltd. Conflicts of interest: none Publication language: English Registered on clinical trials registry? (Y/N): N
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"The capsules were loaded into standard unmarked tablet jars with a four‐digit identifier code. Codes were allocated to one of two treatment groups (1 or 2), using an online random sequence generator"
Allocation concealment (selection bias)	Low risk	"Coding, labelling and randomisation were carried out by the supplier and codes were not broken until the analysis was complete"
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Double‐blind" study "The active and placebo capsules were prepared and supplied by the manufacturer (Equazen). They performed the randomisation and retained the allocation until the study and the analysis was complete. They then released the information on the allocation" (personal communication)
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Double‐blind" study "The active and placebo capsules were prepared and supplied by the manufacturer (Equazen). They performed the randomisation and retained the allocation until the study and the analysis was complete. They then released the information on the allocation" (personal communication)
Incomplete outcome data (attrition bias) All outcomes	Low risk	"Of the 76 contact lens wearers recruited, 52 completed the trial (placebo N = 24, EPO N = 28). The principal reason for dropout was non‐compliance. All subjects, including dropouts, were included in the statistical analysis. Missing data was incorporated using the 'last observation carried forward method'" A total of 26/76 participants (31.6%) discontinued the study
Selective reporting (reporting bias)	Unclear risk	No access to study protocol nor clinical trials registry
Other bias	High risk	Treatment and placebo formulations were provided by a supplier "The manufacturer had no involvement in the study other than supplying the capsules" (personal communication)