While half-shield players were at greater risk of facial lacerations, Meeuwisse points out, those with the full-face shield had lacerations, too -- but they tended to be 'burst' or crush-type injuries at the chin. "With the half-shield, the lacerations tended to be around the mouth and the eye and were potentially a lot more serious."
The number of concussions was not significant, says Meeuwisse, but the severity was worse in players with half-shields. "We didn't look at specifically why, but with the full-face shield, the helmet is actually anchored on the head by the shield because it cups the chin. With the half-shield, it can slip back and expose the forehead."
Facial protection is "one of the most controversial or heated discussion topics in the sport" because the players think it will restrict their vision, says Meeuwisse. "A few players say, 'If I have a full face protector on, I can't see the puck at my feet.'"
"The great thing about this study -- and the reason we're so confident about the results -- is that we had a natural experiment, exactly the same caliber of players, same rules, same officiating, same ice surface, same everything. The only difference was the facial protection," says Meeuwisse, who is also team physician for the National Hockey League's Calgary Flames.
While their results might be applied to high school-level play, "we can't say that's true," says Meeuwisse. "When you get into less mature players, young adults, [the effect] might be different. Full-face shields might have a different effect on an immature neck or an immature head."
Lori Livingston, PhD, associate professor of kinesiology and physical education at Wilfrid Laurier University in Waterloo, Ontario, has also researched the issue. She provided independent commentary on the study for WebMD, calling it "solid work."
"My major comment [is] they could have gone a step further. It's rather disturbing that there were still 34 head and face injuries, even when wearing full-face shield," says Livingston, who has played college-level hockey and coached women's field lacrosse.
The way in which games are officiated should be addressed, she adds. "Because players are wearing equipment, officials tend to be more lenient. We should have very strict rule enforcement. Any injury up around the face should be a penalty."