Summary of findings 2. Combined oral omega‐3 and omega‐6 PUFAs versus placebo.
| Combined oral omega‐3 and omega‐6 PUFAs compared with placebo for dry eye | ||||||
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Patient or population: people with dry eyea Settings: primary care setting Intervention: combined oral omega‐3 and omega‐6 PUFAsb Comparison: placebo | ||||||
| Outcomes | Illustrative comparative risks* (95% CI) | Relative effect (95% CI) | No. of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Assumed risk | Corresponding risk | |||||
| Placebo | Combined oral omega‐3 and omega‐6 PUFAs | |||||
| Symptoms of dry eye at 1‐month (with actual follow‐up ranging from 3 to 6 months) | The Oral sea buckthorn oil study 2010 evaluated eight dry eye symptoms, and reported that the PUFA intervention was more efficacious in reducing ocular burning (P = 0.05) than placebo at 3 months of follow‐up. Creuzot 2006 assessed eight dry eye symptoms, and reported that the number of participants who had specific symptoms ameliorated was significantly greater in the PUFA supplement group compared with the placebo group for conjunctival hyperemia (P = 0.045), reflex lacrimation (P = 0.047), sensations of dryness (P = 0.059), and discomfort (P = 0.091). Creuzot‐Garcher 2011 assessed six dry eye symptoms and reported no significant inter‐group difference except in one sub‐domain (sensation of eye fatigue; P = 0.044). Brignole‐Baudouin 2011 quantified five dry eye symptoms to derive a 'global subjective dry eye score' and reported that neither the global score, nor the analysis of each symptom showed a significant difference between groups at the 3‐month study endpoint. |
Not explicitly reported (4 studies) |
⊕⊕⊝⊝ lowc | No relevant combinable data were available for this outcome, as studies either did not provide quantitative data or used different measurement scales. | ||
| Ocular surface staining at 1‐month (with actual follow‐up ranging from 3 to 6 months) | No significant intergroup difference was observed for corneal fluorescein staining at the study endpoint of 3 months (Brignole‐Baudouin 2011), and 6 months (Creuzot‐Garcher 2011). Creuzot 2006 reported that the PUFA supplement had an effect on corneal fluorescein staining, whereby at six months of follow‐up, 32% of participants had no corneal staining compared with 25% of participants in the placebo group. | Not explicitly reported (3 studies) |
⊕⊕⊕⊝ moderated | No relevant combinable data were available for this outcome, as studies either did not provide quantitative data or used different rating scales. | ||
| Schirmer test (aqueous tear production, measured in mm/5 min, with higher scores indicating more tear production) at 1‐month (with actual follow‐up ranging from 3 to 6 months) | The pooled summary estimate from four studies (Brignole‐Baudouin 2011; Creuzot 2006; Creuzot‐Garcher 2011; Oral sea buckthorn oil study 2010) showed no difference between the PUFA and placebo supplement groups (MD 0.66, 95% CI ‐0.45 to 1.77 mm/5 min, n=455, I² = 0%). | 455 (4 studies) | ⊕⊕⊕⊝ moderated | |||
| Change in tear film stability, measured using tear break‐up time (TBUT) with fluorescein (in seconds, with higher scores indicating greater tear film stability) at 1‐month (with actual follow‐up ranging from 3 to 6 months) | The pooled summary estimate from four studies (Brignole‐Baudouin 2011) indicated a significant improvement with combined omega‐3 and omega‐6 supplementation relative to placebo (MD 0.55, 95% CI 0.04 to 1.07 seconds, n=455, I² = 0%). | 455 (4 studies) |
⊕⊕⊕⊝ moderated | |||
| Change in tear osmolarity (measured in mOsmol/L, with reductions in osmolarity indicating clinical improvement) at 1‐month (with actual follow‐up at 3 months) | In Oral sea buckthorn oil study 2010, tear osmolarity was reported to increase in both groups, but the increase (worsening) was significantly greater in the placebo group after adjustment for "significant" covariates (P = 0.04). | 83 to 96 (1 study) |
⊕⊕⊝⊝ lowe | |||
| Adverse event: gastrointestinal disorders at 1‐month (with actual follow‐up at 3 months) | Brignole‐Baudouin 2011 reported that four (6.0%) participants in the PUFA intervention group and five (7.1%) participants in the placebo group experienced treatment‐related, non‐ocular adverse events. | 138 (1 study) |
⊕⊕⊝⊝ lowe | |||
| *The basis for the assumed risk (ie, the median control group risk across studies) is provided in the footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). ALA: alpha‐linolenic acid; CI: confidence interval; DHA: docosahexaenoic acid; EPA: eicosapentaenoic acid; MD: mean difference; PUFA: polyunsaturated fatty acid; RCT: randomized controlled trial; TBUT: tear break‐up time. | ||||||
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GRADE Working Group grades of evidence.
High quality: further research is very unlikely to change our confidence in the estimate of effect.
Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
Low quality: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
Very low quality: we are very uncertain about the estimate. aDry eye in individuals with (non‐specific) dry eye (Oral sea buckthorn oil study 2010), mild to moderate dry eye disease (Brignole‐Baudouin 2011; Creuzot 2006), or moderate dry eye disease (Creuzot‐Garcher 2011). bDaily dose of EPA from 28 mg to 427.5 mg; DHA from 285 mg to 392 mg; "omega‐6" 15 mg; γ‐linolenic 82 mg; linoleic acid 126. cDowngraded one level for risk of bias and one level for inconsistency. dDowngraded one level for risk of bias. eDowngraded one level for risk of bias and one level for imprecision. | ||||||