Google Admits Glass Can Cause Pain
 

Not only can Google Glass cause pain, they can also cause shame and embarrassment when you wear them. "You're on one leg [or the other] as you walk, but try to stand on one leg for a long time and you'll feel tension, because you're not using it how it's normally used," Dr. Peli said. "If you're looking at the Glass for a minute, you're holding it there for sixty times longer than normal."

http://www.hardocp.com/news/2014/05/...ss_cause_pain/