NCT01107964.

Methods	Study design: randomized, parallel‐group, controlled trial Study site(s): single center Number randomized (total and per group): 27 participants in total; 13 participants in the omega‐3 treatment group and 14 participants in the placebo group Unit of randomization (individual or eye): not reported Exclusions after randomization: not reported Losses to follow‐up: 1 participant in each group Number analyzed (total and per group): 25 participants in total; 12 participants in the omega‐3 treatment group and 13 participants in the placebo group Unit of analysis (individual or eye): individual (worse eye) Reported power calculation? (Y/N): N Reported subgroup analysis? (Y/N): N
Participants	Participant characteristics Country: United States Age (mean ± SD, range): 58 years in total (interquartile range [IQR]: 49.5 to 67.5 years); 54 years [IQR: 44.5 to 65 years] in the omega‐3 treatment group and 60 years [IQR: 55 to 67 years] in the placebo group Gender: 4 men and 23 women in total; 1 man and 12 women in the omega‐3 treatment group, and 3 men and 11 women in the placebo group Inclusion criteria: 1. Age > 18 years 2. Typical symptoms of dry eye (photophobia, burning, foreign body sensation, blurred vision improved with blinking) 3. Schirmer test < 8 mm/5 min 4. Fluorescein tear break‐up time < 8 seconds 5. No current use of dry eye treatment (except artificial lubrication) 6. Signature on consent form Exclusion criteria: 1. Infectious keratoconjunctivitis or inflammatory disease unrelated to dry eye 2. Eyelid or eyelash abnormalities 3. Alteration in the nasolacrimal apparatus 4. Treatment with drugs affecting tearing 5. Concomitant ocular therapies 6. Topical ophthalmic steroids taken during the 4 weeks before the study 7. Pregnant/breast‐feeding women 8. History of liver disease 9. History of fish and/or shellfish allergy or hypersensitivity 10. History of corn allergy or hypersensitivity 11. Treatment with systemic anticoagulation therapy 12. Patients with bleeding disorders and those receiving anticoagulation (eg, warfarin, enoxaparin, dipyridamole, clopidogrel) Equivalence of baseline characteristics? (Y/N): Y
Interventions	Intervention #1 (omega‐3 treatment group): omega‐3‐acid ethyl esters, 1 g capsule, 4 times daily Intervention #2 (control group): placebo (corn oil) capsules, 1 g capsule, 4 times daily Length of follow‐up: 45 days Notes: none
Outcomes	Primary outcome(s): change from baseline in OSDI score Secondary outcome(s): change from baseline in each of Schirmer test; lissamine green staining; TBUT Adverse events reported? (Y/N): Y Measurement time points (specify intervals at which outcomes were assessed): not reported Other issues with outcome assessment (eg, quality control for outcomes, if any): none
Notes	Recruitment status: completed Last post updated: December 2017 Results first posted: December 2017 Registered on clinical trials registry? (Y/N): Y (clinicaltrials.gov ‐ NCT01107964)
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method of random sequence generation was not reported
Allocation concealment (selection bias)	Unclear risk	Allocation concealment was not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	"Masking reported to be: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)" However method of masking is not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	"Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)" However method of masking is not reported
Incomplete outcome data (attrition bias) All outcomes	High risk	Two participants (7.4%) (1 in each group) who were randomized were not included in the analysis
Selective reporting (reporting bias)	Low risk	All prespecified outcomes from the clinical trial registry are reported
Other bias	Unclear risk	Information obtained was from the clinical trial registry, and further publication was not identified