Researchers were looking into worries that the equipment, while preventing eye injuries, might encourage players to get more physical and violent overall - which they termed "the gladiator effect" - leading to an increase in injuries.

"There's often this concern… that if we provide additional protection in the way of some type of equipment or padding that players will then be more aggressive and actually create more injuries because of the increased aggression," said Andrew Lincoln, head of sports medicine research at MedStar Health Research Institute at Union Memorial Hospital in Baltimore.

However that did not appear to be the case, and concussion rates, for example, were similar in states where eyewear was and was not required during the study.

Lincoln, who was not involved in the new research, said that in addition to concerns about athletes becoming more aggressive, some administrators were worried about the negative effects of adding more equipment for athletes to buy and more rules for referees to enforce. Cages used for eye protection run about $25 to $80.

When a similar mandate was introduced in high school girls' lacrosse, he added, veteran athletes were not fans.

"There was a strong negative reaction among players who had played the game for a number of years and were not used to using it and thought it affected their vision negatively," Lincoln told Reuters Health.

He said it was reassuring that the new analysis didn't find an increase in concussions or other collision-related injuries in states that had protective eyewear rules.

"We have very few of these formal evaluations of a safety intervention or a policy change in various sports," Lincoln said. Even though it made sense that eyewear would reduce at least certain kinds of injuries, "We're never quite sure how things are going to work out in real life."

The new research covers 180 high schools during the 2009 and 2010 fall field hockey seasons. In 2009, six states had policies mandating protective eyewear for their athletes: Connecticut, Maine, Massachusetts, New Hampshire, New York and Rhode Island.

As of 2011-2012, the National Federation of State High School Associations now requires all field hockey players wear the equipment.

At high schools included in a sports-injury database, there were 212 eye, face and head injuries during the 2009-2010 and 2010-2011 seasons. Those types of injuries are most often due to athletes being struck by a wooden field hockey stick or a ball, researchers led by Dr. Peter Kriz from Brown University in Providence, Rhode Island, said.

In states that required protective eyewear, the average 20-athlete team had one of those injuries for every 106 practices and games. In states without those requirements, that rate was one injury for every 72 practices and games for each team.

There was one eye injury among 39 schools with equipment requirements during those seasons, compared to 21 eye injuries in 141 teams in states without the mandate, according to findings published Monday in Pediatrics.

"This study adds to an accumulating body of evidence, most recently demonstrated in high school women's lacrosse, that mandated protective eyewear effectively and significantly reduces the incidence of head and facial (including eye) injuries in female athletes where injury from player contact and playing equipment pose risk," Kriz told Reuters Health in an email.

"We encourage players to adopt protective eyewear early, at a young age, regardless of the contact/collision sport they play. Wearing this gear will become second nature, and they will transition easier to other sports requiring facial protection."

Lincoln agreed that it's easiest for younger players to adopt the new gear, before they're used to playing without it.

"I hope different sport governing bodies look at these studies and will be more open to protective equipment for games," he said.

SOURCE: bitly.com/kSEGVh Pediatrics, online November 12, 2012.

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