Blueberry Effects on Dark Vision and Glare Recovery

Placebo-controlled Cross-over Studies Examining Blueberries Effects on Dark Vision and Recovery After Photo-bleaching

Clinical evidence for effects of plant anthocyanins on vision, and particularly night vision is controversial. Two clinical trials were conducted to investigate whether blueberry juice consumption affected visual dark adaptation, functional night vision, and recovery after photo-bleaching of the retina. One trial (S2) employed a 3 week intervention and washout period, and two doses of blueberries plus a placebo. The other trial (L1) employed a 12 week intervention plus an 8 week washout and tested one blueberry juice dose against a juice placebo.

Vision Tests: 1. Dark adaptometry, 2. scotopic visual acuity, 3. scotopic contrast sensitivity, 4. rod/cone conversion, 5. recovery after retinal photobleaching

Inclusion Criteria:

• visual acuity better than 6/7.5 on EDTRS acuity chart at 2.5m
• visual contrast sensitivity within normal range at 2.5m as tested on Visteck 3000
• stereo acuity better than 80 seconds of arc on Frisby stereoacuity test
• no ocular history other than refractive glasses
• no family history of eye disease

Exclusion Criteria:

• family history of retinal degeneration, glaucoma, diabetes, hypertension, cataract, or amblyopia (dimness in vision).
• evidence in subject (upon examination) of amblyopia (dimness in vision), manifest strabismus (unable to focus both eyes on one spot), or anisotropia (non-uniform responsiveness between both eyes).
• intraocular pressure above 21mmHG from an average of three measures using Mentor tonopen-XL