Better eye-hand coordination, better batters

'Keep your eye on the ball' may seem like elementary baseball advice, but clutch hitters know there's something to discerning eyes—and now research can back that up.

Published in the journal Optometry & Vision Science, the study illustrated how faster eye-hand visual motor reaction time (EH-VMRT) among professional baseball players significantly correlated with better plate discipline batting metrics, such as swinging at more pitches inside and fewer outside the strike zone, and the ability to draw walks more often than players with the slowest EH-VMRT.

Eye-hand coordination, the synchronization between the visual and motor systems, is critical in high-speed sport movements but is highly variable among athletes. Especially in baseball, where batters have less than 400 milliseconds to judge a 95-mph fastball from pitch to plate, identifying players based on EH-VMRT can influence roster selection as well as help recognize players who may benefit from performance vision interventions.

Led by Daniel Laby, M.D., former director of the Sports and Performance Vision Center at State University of New York College of Optometry, researchers tested 400 professional baseball players' reaction times using a 32-sensor-pad touch board and compared times to the athletes' plate discipline metrics. Researchers found players with the fastest EH-VMRT not only drew walks 22% more often than those with the slowest EH-VMRT, but also chased 10-12% fewer pitches outside the strike zone and swung at 6-7% fewer pitches in the strike zone.

David Kirschen, O.D., Ph.D., study co-author and professor emeritus at the Southern California College of Optometry at Marshall B. Ketchum University, says it's always been known that vision is important in terms of baseball offensive performance, but it's also been difficult to prove.

"This is the first time we were able to correlate visual performance on a hand-eye, visual reaction time test with on-field performance," Dr. Kirschen says.

"This allows us to test players and tell the coach or team if any given player is performing in the top 80% of other players on their team, or if they fall in the bottom 20% and, therefore, may need some additional training to improve their performance."

Faster EH-VMRT may allow batters longer time to judge pitch trajectory before swinging, authors hypothesize, while slower EH-VMRT may force batters to swing earlier and thereby have less certainty about where the pitch will cross the plate. These miniscule differences "may result in higher rates of swinging at pitches and a lower likelihood to gain a base on balls," authors note.

Additionally, researchers found a statistically significant difference between the top and bottom 20% EH-VMRT groups and plate discipline abilities. This information is critically insightful for baseball teams as they manage rosters and resources, Dr. Kirschen says.

"Each team only has a fixed number of assets to spend on player selection and development," he says. "Knowing that an athlete may have visual deficits that can affect their on-field performance is very valuable information to a team. They want to spend their resources developing players that have the best chance of making the team, and this information helps make that decision. It is not only possible that managers could adopt the information in this study, they have already done so."

Beyond sports: Performance

So what's the takeaway for optometry? Professional baseball players might not be your typical weekday clientele, but that doesn't mean there aren't lessons to be incorporated into routine optometric practice.

Patients often participate in physically demanding exercise or activities, such as after-school sports, work leagues or "weekend warriors," and can benefit from not only regular comprehensive eye care, but also performance vision optimization. Incorporating basic sports and performance vision services can be a low-cost way to meet the needs of these patients, be it providing sports-specific safety eye wear to performance vision training.

Regarding the EH-VMRT study, Dr. Kirschen says their findings could directly apply to military or law enforcement threat detection, or any first responders that need fast visual processing of an emergency. Moreover, Dr. Kirschen says it's important to stress visual optimization and not stop refracting at 20/20.

"If the patient's maximum is 20/20 then terrific, but if their visual system is capable of 20/15 then you need to know that information and provide that service to your weekend warriors who are very serious about their sports," Dr. Kirschen says.

AOA offers sports, performance vision resources

More Americans than ever engage in sports or exercise regularly with nearly 20% of Americans, 15 and older, participating in some form of physical fitness activity or sport, per the U.S. Bureau of Labor Statistics. Ensuring these patients' eyes are protected and function appropriately for their sport or activity is essential to their vision, safety and health.

That's why the AOA Sports & Performance Vision Committee (SPVC) and Advocacy Network (SPVAN) are committed to helping doctors of optometry provide the eye and vision care necessary for patients engaged in sports.

Find information on the Sports & Performance Vision page.

Interested in helping AOA advocate for better SPV policies, regulations and laws? Join AOA's SPVAN to stay updated on SPV advocacy efforts and help identify opportunities to get involved in promoting SPV at a local, state and federal level.

Read more about how optometry helps optimize athletes, from peewee through professional sports and beyond, in the April 2017 edition of AOA Focus.