Bilberry

Vaccinium myrtillus

A folk remedy for night vision with a long reputation and a thin trial record. What evidence exists points at eye fatigue, not at seeing in the dark.

What the evidence supports

Moderate Eye fatigue from screen work Symptom scores improve over 4–8 weeks in several Japanese trials, most funded by extract manufacturers.

Limited Night vision Directly tested in controlled trials and not supported. The wartime pilot story has no trial behind it.

Limited Retinal microcirculation Plausible mechanism from anthocyanins, but human outcome data is sparse.

Limited Dry eye Two small trials, inconsistent endpoints.

Dose used in trials

160–480 mg

per day of extract standardised to 36% anthocyanins. Unstandardised fruit powders are not comparable.

Safety

Well tolerated

No consistent adverse-effect signal at studied doses over the short durations tested.

Ask a doctor first if

Two cases

Anticoagulant therapy, or the fortnight before scheduled surgery.

Open any one for sample size, funding and what it actually measured.

Kamiya et al. · 88 adults · eye fatigue

Eight weeks, 480 mg/day, VDT workers. Subjective ocular-fatigue scores improved; objective accommodation measures did not separate from placebo.

Muth et al. · 15 adults · night vision

Crossover, three weeks. No difference in night visual acuity or contrast sensitivity. Small but well-controlled, and the result has held.

Review · 12 trials · ocular outcomes

Reviewers note that positive trials cluster by funder and region, and that extract standardisation varies enough to make pooling unsound.