Many new Google Glass users have been complaining of headaches and other head pains since they began using their newest toy. Google recruited Harvard optometrist, Dr. Eli Peli, to work for them as a consultant in order to evaluate their newest invention, Google Glass.

Google Glass looks just like a regular pair of prescription glasses, except its lenses function as a wearable computer. By tapping the earpiece and using spoken commands, the mini-computer screens can perform many of the same tasks are your cellphone, such as create calendar alerts and locate a local restaurant. The search-engine giant, Google, has certainly created an innovative device we’ve only seen in futuristic fantasy cartoon shows like the American sitcom, The Jetsons. But with a $1,500 tag price for developers and a market target price of $750 for the public.

The display on the Glass is positioned in the upper right hand corner of the screen, which Peli says, could cause eye strain because users aren’t used to staring anywhere but straight forward for long periods of time. This stretches the eye muscles in an uncomfortable way that most aren’t used to experiencing.

"The only people who look up a lot are some professionals like electricians and painters," Peli told BetaBeat. "Most of us look either straight or down. It's well known that up is less comfortable."

Peli compared using Glass for the first time to someone standing on one leg for a long period of time. He said it’s only uncomfortable because you’re not used to the muscle strain in your legs, which is exactly what’s happening to your eyes, which have their own muscles. Eyestrain is a type of condition called computer vision syndrome, in which there is an eye muscle imbalance or uncorrected vision that is worsened by staring at a computer, according to Mayo Clinic.

"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. If you're looking at the Glass for a minute, you're holding it there for 60 times longer than normal," Peli said.

Peli emphasized the importance, that the sensation users are experiencing is caused by an eye muscle strain and therefore cannot be described as being a headache, which is more of a neurological phenomenon than a muscular one.

"It's not a headache, it's sort of a discomfort in the eye muscles," he added. "To describe it as a headache is inconsistent with how people experience headaches."

In its defense, Google has asked people not to use Glass eyewear for prolonged periods of time because it could cause pain. As a result of Peli's comments, which were first reported Monday, a Google spokesman issued a statement about day-to-day user recommendations:

When anyone gets a new pair of glasses or starts wearing them for the first time there is always an adjustment period until people get used to them. For some it's the same with Glass. We encourage explorers to ease into Glass, just as they would a new pair of glasses. As we note in our help center, Glass is designed for micro-interactions, not for staring into the screen, watching Friday night movie marathons or reading "War and Peace."

"There should be a warning that comes with Glass; that if you start to get a headache, you should limit your use." Chris Barrett, CEO of PR tech firm who holds a Ph.D. in bioinformation systems, and one of the first Google Glass users, told CNET. Barrett felt the pain wasn’t worth it and has since stopped using Glass.