[Mark] Kotsay is not alone. As one of the roughly 16 percent of Americans with light-colored eyes (Kotsay’s are a soft blue), he is more affected by glare, experts say. ...
The root of the problem, said the sports optometrist Dr. Donald Teig, is that light-eyed people lack pigment in their macula, which is “a little dot, about the size of a pinhead, that sits conveniently in the most centralized portion of the eye as light passes through your pupil to get to your retina.”
“It really handles the impact of light better the more pigmented it is,” Teig said.
The concerns for light-eyed athletes came into focus recently when Texas Rangers outfielder Josh Hamilton, who has struggled to hit as effectively during the day as he does at night, revealed that team doctors told him his eye color could be a contributing factor. With a reduced sensitivity to contrast, he has a harder time picking up the seams of the baseball — the part of the ball hitters use, in a fraction of second, to identify what pitch is coming. ...
[R]esearch by the Elias Sports Bureau and The New York Times found that, among players who began their careers since 1970 and had at least 500 day-game plate appearances, 12 of the 19 largest career drops between night- and day-game batting averages belong to light-eyed players.
Among active players, five of the 13 largest gaps are light-eyed players, including Hamilton (a 94-point drop) and San Diego Padres third baseman Chase Headley, who has greenish-blue eyes and a 53-point disparity (.286 to .233) through Thursday. ...
Cashman and Mets General Manager Sandy Alderson each acknowledged the importance of vision in evaluating players but said eye color was not specifically a significant aspect. The form Yankees scouts use to record player information does not even have a line for eye color, Cashman said.
Allard Baird, the vice president for player personnel of the Boston Red Sox, said he had not heard of eye color being a factor discussed by scouts, though he includes a vision section on his player cards where evaluators are asked to assess whether a prospect has any obvious indicators of eye problems.
But Baltimore Orioles Manager Buck Showalter said he had known about this issue “for years.” Showalter said that although scouts have a laundry list of axioms about a player’s body type — “Don’t draft a kid with a beard because it probably means he’s done growing,” Showalter offered as an example — anything that has to do with vision is important to a player’s success.
“To this day, when I see a prospect or a kid we’re going to sign, I’ll look at his eyes,” Showalter said. “Anybody who tells you they don’t notice eye color when they’re evaluating a player probably isn’t a very good scout.”