This is just from memory but here is an interesting story:
During WW II (English or U.S.) fighter pilots would eat Bilberries off of Bilberry Bushes that grew on the the sides of the tarmac or runway because they claimed it gave them night vision or the ability to see in the dark which helped them excute missions with more accuracy such as spotting enemy targets!
Bilberry Extract helps with micro circulation (the little teeny tiny blood vessels that go to your eyes, skin and internal organs; especially the brain) much like Grape Seed Extract which must effect the eyes some how!
Some research on Bilberries:
University of Maryland Medical Center. “Bilberry” URL: http://www.umm.edu/altmed/articles/bilberry-000225.htm
A, Cignarella, et. al. “Novel lipid-lowering properties of Vaccinium myrtillus L. leaves, a traditional antidiabetic treatment, in several models of rat dyslipidaemia: a comparison with ciprofibrate.” URL: http://www.sciencedirect.com/science/article/pii/S0049384896001958
Chu, Wing-Kwan “Bilberry” Herbal Medicine: Biomolecular and Clinical Aspects. 2nd edition URL: http://www.ncbi.nlm.nih.gov/books/NBK92770/
Takikawa, Masahito. “Dietary Anthocyanin-Rich Bilberry Extract Ameliorates Hyperglycemia and Insulin Sensitivity via Activation of AMP-Activated Protein Kinase in Diabetic Mice” URL: http://jn.nutrition.org/content/140/3/527.short
Ichiyanagi, Takashi. “Bioavailability and Tissue Distribution of Anthocyanins in Bilberry (Vaccinium myrtillus L.) Extract in Rats” URL: http://pubs.acs.org/doi/abs/10.1021/jf0602370
Canter, Peter H. “Anthocyanosides of Vaccinium myrtillus (Bilberry) for Night Vision—A Systematic Review of Placebo-Controlled Trials” URL: http://www.surveyophthalmol.com/article/S0039-6257(03)00128-0/abstract