Eye black is a grease applied under the eyes to reduce glare. It is often used by American football, baseball, and lacrosse players, where sunlight or stadium lights can impair seeing an airborne ball.
It is a form of functional makeup.
One of the earliest known instances of a player wearing eye black is baseball legend Babe Ruth, who, in or around the 1930s, used the grease in an attempt to reduce sun glare
A 2003 study by Brian DeBroff and Patricia Pahk tested whether black eye grease actually had anti-glare properties. The subjects of the study were divided into three groups: wearers of eye black, wearers of anti-glare stickers, and wearers of petroleum jelly. The subjects' vision was tested using an eye chart while being exposed to natural sunlight.
The study concluded that eye black reduced glare of the sun and improved contrast sensitivity, whereas commercial anti-glare stickers and petroleum jelly (the control substance) were found to be ineffective