Before he steps up to the plate, Cubs outfielder Ian Happ peers at a bull’s-eye sticker affixed to the inside of his batting helmet, just above the earpiece—a quick depth perception exercise that reminds his brain to utilize both eyes while at bat. This small habit is just one element of Happ’s vision-training routine, which he started after posting career lows in batting average (.226), on-base percentage (.323) and OPS (.757) during the 2021 season. A teammate referred him to Ryan Harrison, owner of SlowtheGameDown, a vision performance program based in Irvine, Calif.
“We want people working on our bodies and swings, but if you can’t see the ball, you’re not going to have much success,” Happ says. “I think it’s a big part of what we do and it’s the least [thing] emphasized or trained.”
Indeed, shoulder presses and squats are workout standbys, but exercises for the eyes are often overlooked. That’s where Harrison—who works with athletes in baseball, football and hockey—concentrates his training. The eye contains six muscles that work together to move it in all directions, like the strings on a marionette. They are divided into two groups: the recti, the primary vertical movers when the eye is abducted, or looking away from the nose; and the oblique, used when the eye is adducted, or looking towards the nose. During his initial evaluation with an athlete, Harrison uses a series of tests and drills, most of which originate from another time—and another Harrison. After playing baseball at Cal, Ryan’s father Bill became an eye doctor and later began working with the Royals as a vision-training specialist in 1971. He went on to work with 15 MLB organizations and several NCAA baseball programs before his death in 2019.
“A lot of the stuff we do today is based on what they were doing in the ’70s,” says Ryan. “The technology is updated. But the brain and the eyes haven’t changed. It’s really about how we’re using those skill sets and enhancing them.”
Harrison’s evaluation mainly tests eye movement and motor control, focusing on those six muscles of the eye and how they work together with the brain to execute specific activities, such as following someone’s finger as it moves into different areas of your gaze. One of the tools he uses to assess these vision-processing skills is called the NeuroFit One, a medical-grade device that records, analyzes and measures eye-movement responses to different stimuli using a high-speed camera.
Once Harrison establishes a baseline, he will tailor his training to focus on different vision skills. These include binocularity, also known as eye teaming, which is the ability to focus on an object with both eyes to create a single image and thus, make accurate spatial judgments; and peripheral awareness, or the ability to see objects and movements that are not directly in front of you, which can ultimately allow athletes to react more quickly and with better anticipation.
The first season after working in the program, Happ made his first All-Star team. He hit 45 points higher and added 19 points to his OBP. In the two subsequent years, Happ’s walk rate increased, including a career-high 99 free passes in 2023.
“When you play at this level, the difference between success and failure is [so small],” Happ says. “Fouling the ball straight off or squaring the ball up at 95 or 98 miles per hour is the difference between centimeters. For what we do, as hitters, I think [vision training] is a pretty undervalued part of the whole equation.”