For years, most researchers thought July 4 fireworks-related eye injuries were likely caused by what’s called blast overpressure: that the pressure wave unleashed by the explosion increased the pressure in the eye, causing bleeding and even rupture of the eyeball.
Of the approximately 10,000 fireworks-related injuries treated in emergency rooms annually, more than 2,000 involve damage to the eye. For fireworks, as in other applications, understanding the mechanism of injury can help encourage evidence-based regulations and protective gear. And in fact, states with laws restricting the use of projectile-based fireworks see fewer fireworks-related eye injuries.
Stefan Duma, a Virginia Tech expert in injury biomechanics, published research five years ago revealing that the injuries to the eyeball were a result of shrapnel released during the explosion, not the increase in pressure.
Investigating the affect of explosions on the eye was familiar territory for Duma. He and his team had spent several years studying blast-related eye injuries among soldiers.
“We had done a lot of blast work for the military, where we were looking at eye injuries caused by that pressure wave. We applied those techniques to studying bottle rockets,” Duma said.
Duma’s research team simulated fireworks using gunpowder and measured the pressure inside and outside the eyeball. They also looked for signs of damage including corneal abrasions, scleral damage and globe rupture.
Duma’s work on eye-injury risk for a variety of applications resulted in the development of a specialized dummy headform embedded with sensors that measure the force experienced by the eye and the surrounding bones, and a better understanding of the quantitative relationship between those forces and the likelihood of serious eye injury.
“We were able to show that it’s not the blast — it’s the projectile,” said Duma, the Harry Wyatt Professor of Engineering in the College of Engineering and the interim director of the Institute for Critical Technology and Applied Science. “The pressure of the blast itself is too low at that level to cause any eye injury.”
His work with the military led to recommendations for protective eyewear for soldiers. It also launched research projects with toy companies, who sought Duma out to evaluate the eye injury risk of products like Nerf darts, water pistols, and lightsabers.
Sometimes, of course, safety is a matter of common sense.
“Don’t shoot bottle rockets at each other,” Duma said.
Source: Virginia Tech
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