Bilberry (Vaccinium myrtillus) and Eye strain / eye health: evidence and sources

We have systematically reviewed placebo-controlled trials of V. myrtillus-extracted anthocyanosides for evidence of positive effects on night vision. Searches of computerized databases and citations in retrieved articles identified 30 trials with outcome measures relevant to vision in reduced light. Of these, 12 were placebo-controlled. The 4 most recent trials were all randomized controlled trials (RCTs) and were negative in outcome. A fifth RCT and 7 non-randomized controlled trials reported positive effects on outcome measures relevant to night vision. Negative outcome was associated with more rigorous methodology but also with lower dose level and extracts from geographically distinct sources that may differ in anthocyanoside composition. Healthy subjects with normal or above average eyesight were tested in 11 of the 12 trials. The hypothesis that V. myrtillus anthocyanosides improves normal night vision is not supported by evidence from rigorous clinical studies. There is a complete absence of rigorous research into the effects of the extract on subjects suffering impaired night vision due to pathological eye conditions. Evidence from methodologically weaker trials and auxiliary evidence from animal studies, trials of synthetic anthocyanosides, and a recent randomized controlled trial of Ribes nigrum (black currant) anthocyanosides may warrant further trials of V. myrtillus anthocyanosides in subjects with impaired night vision.