Need to read some fine print? Wolf down a candy bar first and you might see it better. Eating dark chocolate improved visual acuity, and small-letter contrast sensitivity in particular, for nearly two hours, an unusual study in JAMA Ophthalmology found. Researchers evaluated 30 patients without pathologic eye disease for visual acuity and large- and small-letter contrast sensitivity 1.75 hours after they consumed either dark or milk chocolate.

Results showed that small-letter contrast sensitivity was significantly higher after consumption of dark chocolate compared with milk chocolate; large-letter contrast sensitivity was slightly higher after consumption of dark chocolate compared with milk chocolate; and visual acuity improved slightly after consumption of both dark and milk chocolate. Overall, combined results from the tests showed a significantly higher improvement in patients who ate dark chocolate than those who ate milk chocolate. The researchers attribute the differential to the higher amount of flavanols in dark chocolate.

“Consumption of a commercially available dark chocolate bar improves the ability to see low- and high-contrast targets, possibly owing to increased blood flow” and the highly vascularized nature of the macula, the study concluded. However, the authors caution, “The duration of these effects and their influence in real-world performance await further testing.” Recruitment for future studies should be easier than most.

Rabin JC, Karunathilake N, Patrizi K. Effects of milk vs dark chocolate consumption on visual acuity and contrast sensitivity within 2 hours. JAMA Ophthalmol. April 26, 2018. [Epub ahead of print].