Eye black grease, a combination of beeswax and pigment used by many athletes to combat sun glare, provides better contrast sensitivity than anti-glare stickers, Yale researchers have found.
"Eye black grease appears to be more than just psychological war paint," said principal investigator Brian M. DeBroff, M.D., assistant professor of ophthalmology at Yale School of Medicine. "When we started this study, we weren't expecting to find any type of anti-glare properties or any improvement in visual contrast with eye black grease, but it made improvements in both these areas and was more effective than other products."
Published in the July issue of Archives of Ophthalmology, the study examined if eye black grease or anti-glare stickers improved contrast sensitivity during sunlight exposure. DeBroff and his co-author Patricia J. Pahk, M.D., looked at 46 students, aged 18 to 30, for contrast sensitivity with and without anti-glare products. Each participant served as an internal control by initially being tested without anti-glare products and then again after being randomized to one of three groups that used either eye black grease, anti-glare stickers, or petroleum jelly placebo during direct and unobstructed sunlight exposure.
"There was no improvement in contrast sensitivity as compared to control with either anti-glare stickers or petroleum jelly," said DeBroff. "Based on these results, eye black grease does appear to have antiglare properties, whereas anti-glare stickers do not."
DeBroff said there was a roughly one level of sensitivity improvement between no products vs. eye black grease, according to the Pelli-Robson chart, a tool used to measure contrast sensitivity.
Eye black grease and no-glare stickers have been used by professional baseball and football players for decades to reduce glare from sunlight and stadium lighting. These light sources can affect an athlete's ability to see detail and sensitivity to contrast. Previous studies have shown that the higher an athlete's sensitivity to contrast, the better he or she can see an object as its speed increases.
"Even earlier, players used to smear burnt cork on their cheeks," said DeBroff. "No study has ever been conducted to ascertain its effectiveness and determine if it merely represents an aggressive look or psychological advantage."
DeBroff said anti-glare stickers, which are patented fabric materials, have become more popular because they don't smear and some are manufactured with team logos. His results show there is no benefit to their use.