Bilberry extracts have been extensively tested in the sixties on different conditions of impairment of visual functions. The extracts alone or in association with b-carotene and vitamin E, administered to healthy subjects or to patients with visual disorders, induced in a high number of subjects a significant improvement in night vision, a quicker adaptation to darkness and faster restoration of visual acuity following exposure to a flash of bright light(1-5).
Trials performed on air-traffic controllers, air pilots, car and truck drivers showed that anthocyanins-containing extract was able to improve the night vision and the adjustment to darkness(6-8).
Later on, Forte et al.(9) confirmed the results obtained in the above reported studies.
Recently Canter and Ernst(10) published a critical review of the clinical studies (1964-2001) concerning the activity of the V. myrtillus extracts on human vision under reduced light condition.
Thirty trials have been retrieved, of these 12 were placebo-controlled. Of these 5 were randomized controlled trials and 7 were placebo-controlled non randomized trials. The 4 most recent trials were all randomized controlled trials (RCTs) with a negative outcome. A fifth and 7 non randomized controlled studies reported positive effects on outcome measures relevant to night vision. Nevertheless the fifth RCT and 7 placebo-controlled, but non randomized trials, all report positive effects on at least one outcome measure relating to vision in reduced light.
The negative results however are confounded by several factors: different products, i.e. different phytochemical composition have been used in the trials; the anthocyanins amount administered varies between trials and the trials with a negative outcome corresponds to the lowest doses utilized (36, 40, 48 and 120 mg anthocyanosides); the enrollment criteria.
As for the effects of bilberry extract on night vision the available data has not allowed to draw a definite conclusion.
- Jayle G.-E, Aubert L., Thérapie 19, 171 (1964).
- Jayle G.E., Aubry M., Gavini H., Braccini G., de la Baume C., Ann. Ocul. 198, 556 (1965).
- Fiorini G., Biancacci A., Graziano F.M., Ann. Ottal. Clin. Ocul. 6, 371 (1965).
- Urso G., Ann. Ottal. Clin. Ocul. 93, 931 (1967).
- Zavarise G., Ann. Ottal. Clin. Ocul. 94, 209 (1968).
- Belleoud L., Leluan D., Boyer Y., Rev. Méd. Aéro. Spat. 5, 45 (1966).
- Belleoud L., Leluan D., Boyer Y., Rev. Méd. Aéro. Spat. 6, 5 (1967).
- Rouher F., Sole P., Ann. Med. Accidents Traffic, 3-4 (1965).
- Forte R., Gazzaniga D., Iacobelli L., Tassone R., Rispoli M., Ann. Ottal. Clin. Ocul. 122, 325 (1996).
- Canter P.H., Ernst E., “Anthocyanosides of Vaccinium myrtillus (bilberry) for night vision–a systematic review of placebo-controlled trials.”, Surv. Ophthalmol. 49, 38 (2004).