Oleñik 2013.

Methods	Study design: randomized, parallel‐group, controlled trial Study site(s): single‐center Number randomized (total and per group): 64 participants in total; 33 participants in the omega‐3 treatment group; 31 participants in the control group Unit of randomization (individual or eye): individual Exclusions after randomization: 2 participants withdrew due to drug intolerance, and 1 participant did not pursue treatment in the omega‐3 treatment group Losses to follow‐up: none Number analyzed (total and per group): 61 participants in total; 30 participants in the omega‐3 treatment group; 31 participants in the control group Unit of analysis (individual or eye): individual (right eye) Reported power calculation? (Y/N): N Reported subgroup analysis? (Y/N): N
Participants	Baseline characteristics Country: Spain Age (mean ± SD, range): 58 years in the omega‐3 treatment group; 54 years in the control group Gender: 9 men and 24 women in the omega‐3 treatment group; 9 men and 22 women in the control group Inclusion criteria: 1. 18 to 85 years of age 2. Diagnosis of meibomian gland dysfunction based on criteria identified in the 2011 International Work Shop on meibomian gland dysfunction 3. Able to participate in the study 4. Provision of informed consent Exclusion criteria: 1. Atopy or allergic disorders 2. Contact lenses 3. Ophthalmic laser treatment less than 3 months before enrollment 4. Pregnancy 5. Systemic diseases and general treatments 6. Blepharitis without meibomian gland dysfunction diagnosis 7. Ocular disorders and eye drops other than artificial tears 8. Obvious infection Equivalence of baseline characteristics? (Y/N): Y
Interventions	Intervention #1 (treatment group): oral capsule containing eicosapentaenoic acid 42.5 mg and docosahexaenoic acid 350 mg and 30 mg docosapentaenoic acid (Brudysec 1.5 g, Brudy Lab SL), 3 times daily, 1 capsule at a time. Daily dose of: 127.5 mg eicosapentaenoic acid, 1050 mg docosahexaenoic acid, and 90 mg docosapentaenoic acid Intervention #2 (control group): placebo capsule (500 mg) containing sunflower oil (dose not reported), 3 times daily, 1 capsule at a time Length of follow‐up: 3 months Notes: participants in both groups were instructed to apply a warm compress for 5 minutes and to scrub the eye with diluted baby shampoo and to use artificial tears without preservatives; participants were required to discontinue use of nutritional supplements and related treatments, such as antibiotics, non‐steroidal anti‐inflammatory drugs, corticosteroids, and tears with vitamins, for at least 15 days before the baseline visit; ocular lubricants without nutritional agents were not restricted
Outcomes	Primary outcome(s): TBUT; corneal and conjunctival fluorescein staining, both measured as data at study endpoint Secondary outcome(s): Schirmer test without anesthesia; OSDI; meibomian gland expression and secretion; evaluation of lid margin inflammation, all measured as data at study endpoint Adverse events reported? (Y/N): Y Measurement time points (specify intervals at which outcomes were assessed): baseline, months 1, 2, and 3 Other issues with outcome assessment (eg, quality control for outcomes, if any): none
Notes	Study dates: enrollment between March 2012 and December 2012 Funding source(s): "the food supplements used this trial were provided by Brudy Lab SL, Barcelona, Spain" Conflicts of interest: "the authors report no conflict of interest in this work" 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)	Unclear risk	Method of randomization was not reported
Allocation concealment (selection bias)	Unclear risk	Allocation concealment was not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Double‐masked" study "Throughout the randomized study, the investigators and patients were blinded to the treatment assignments"
Blinding of outcome assessment (detection bias) All outcomes	Low risk	"Double‐masked" study "Throughout the randomized study, the investigators and patients were blinded to the treatment assignments"
Incomplete outcome data (attrition bias) All outcomes	High risk	3/64 (4.7%) participants in the treatment group withdrew (2 due to drug intolerance; 1 did not pursue the treatment), and they were not included in the analysis, even though the paper states that "both intra‐group and inter‐group comparisons were made with an intention‐to‐treat analysis"
Selective reporting (reporting bias)	Unclear risk	No access to study protocol or clinical trials registry
Other bias	High risk	Treatment supplements were provided by a supplier