Normal good vision for an average citizen is 20/20, defined as being able to see at a distance of 20 feet what should be seen 20 feet away.
But athletes — specifically baseball players, and more specifically hitters — are not average citizens. As a group, they have exceptional vision. And if they merely have good vision?
"If you have 20/20 vision, you have a problem in baseball," said Dr. Daniel Laby, director of the Sports and Performance Vision Center at State University of New York's College of Optometry. "If you were a Minnesota Twin coming in to see me and you measured at 20/20, I would say you need a correction."
Laby considers himself part of the solution, and several teams agree. He currently works with five different major league baseball organizations, helping them do vision assessments on everyone from established stars to prospects. Laby said he examined every first-round pick chosen in the MLB draft earlier this month as well as several hundred other draftees. This past weekend, he evaluated 30 prospects who will be draft-eligible next year.
The reason is simple: As teams look for performance edges, vision has emerged as an important analytic. While he wouldn't divulge the identity of the five teams he works with, they fit a common description in Laby's eyes.
"There are different teams: forward-looking and teams looking in the past," Laby said. "We've been fortunate that teams have picked us because they're forward-looking. We're a small piece of the puzzle, but we're a symptom of the outlook of teams. They want to leverage technology and knowledge."
A lot of players, of course, don't need help. A 20-year-old study of about 300 ballplayers showed that, on average, they have 20/12 vision — two lines better than 20/20 on the eye chart, and the ability to see things at a distance of 20 feet that would normally be seen from 12.
That makes sense when you consider what they are asked to do. The average pitch takes about four-tenths of a second to travel from the pitcher to home plate. Most of that time is consumed by firing muscles and other processes, leaving about one-tenth of a second — a third of a blink, as Laby describes it — to see the ball.
Laby works with players to ensure they have the better-than-average vision necessary to focus on the ball and hit it in that brief moment.
"But we're also looking at hand-eye coordination, concentrating on targets and all the other things that need to be optimized for a batter," Laby said."
One of his most famous clients is Manny Ramirez, who began using one of Laby's visual drills when he was a member of the 2004 Red Sox. With vision, even subtle changes can be important.
"It's a huge component and a first component. Vision is so easy to fix," Laby said. "There are players who don't go further in their careers because of that one missing piece."