Efficacy of nutritional supplementation with omega-3 and omega-6 fatty acids in dry eye syndrome: a systematic review of randomized clinical trials
To critically appraise scientific evidence regarding the efficacy of nutritional supplementation with omega-3 and omega-6 fatty acids for the treatment of dry eye syndrome (DES).Methods:
A systematic review of randomized clinical trials was performed. Two independent reviewers selected and analysed the scientific papers that met inclusion and exclusion criteria. Objective and subjective efficacy outcomes were assessed.Results:
The trials involved a total of 2591 patients in fifteen independent studies. All studies were published between 2005 and 2015. The supplements used were mostly omega-3 and omega-6 in different proportions. Subjective improvement was measured using mainly Ocular Surface Disease Index (OSDI) test and Dry Eye Severity Score (DESS) test: significant differences in favour of the experimental group were found in seven of the studies. The objective amelioration was assessed by lacrimal function parameters: Tear break-up time (TBUT) significantly increased in nine studies and Schirmer's test in four studies.Conclusion:
We observed a discrete improvement in the parameters of tear function. Scientific evidence is not strong enough to systematically recommend the use of omega-3 and omega-6 fatty acids as a standalone treatment of DES independently from its aetiology. However, they could be considered as an effective alternative to topical treatment in patients with DES secondary to certain pathologies.