Evaluation of Eye Injuries Caused by Baseballs of Varying Hardness.

Principal Investigator: Paul F. Vinger, MD

Institution: Vision Performance and Safety Service, Tufts University School of Medicine, Medford, MA

Title: Baseball Hardness as a Risk Factor for Eye Injuries.

Paul F. Vinger, MD; Stefan M. Duma, MS; Jeff Crandall, Ph.D. Vision Performance and Safety Service, Tufts University School of Medicine, Medford, MA (Dr. Vinger), and the Automobile Safety Laboratory at the University of Virginia, Charlottesville, VA (Mr. Duma, Dr. Crandall)

Abstract: Baseball is the leading cause of sports related eye injuries in youth. It is known that softer baseballs reduce the potential for brain injury, but it has been speculated that softer baseballs may increase eye injuries by intruding more on the orbit. It has been claimed that softer baseballs would change the “feel” of the game. Objectives. To determine the orbital intrusion and eye injury potential of baseballs of varying hardness, and whether the player can feel the difference between baseballs of varying hardness. Design. Experimental. Main Outcome Measures. Orbital force and penetration of baseballs of baseballs of various hardness into an artificial orbit. Ability of subjects of varying age and baseball experience to determine the hardness of baseballs. Results. The peak orbital force and force onset rate from the softer baseballs, all at impact velocities, were less than the force and force onset rate from baseballs which had hardness equal to, or greater than, major league baseballs. The softest (10% of major league hardness) baseballs intruded into the orbit significantly more than the balls that were 15% of major hardness, or harder, and adult 20% or harder than major league ball. Conclusion. The potential for injury to the unprotected eye from soft baseballs is significant, but not greater than from a major league baseball. Baseballs which are 15% to 20% of major league ball hardness are recommended for youth baseball because these balls feel like a major league ball, reduce the potential for brain injury, cause less pain on impact, and do not increase the potential for eye injury to the unprotected player. The only way to minimize eye injuries in youth baseball is by means of protective eyewear.