Lots has been made about Secretary of State Hilary Clinton and her glasses. New York Magazine, for example, ran a photo gallery of how Clinton used her glasses to convey emotions during the Benghazi hearings on the Hill.

Today, State Department spokesman Philippe Reines responded to the magazine's photogallery providing a serious explanation for the new accessory:

"She'll be wearing these glasses instead of her contacts for a period of time because of lingering issues stemming from her concussion. With them on she sees just fine. In fact, she got a kick out of this when she saw it crystal clearly."

If you look closely, the left lens has little lines. The New York Daily News consulted with eye specialists who said that was a Fresnel prism placed on her glasses.

The News explains:

"'If she's wearing a Fresnel prism, then she has double vision without it,' said Dr. Mark Fromer, medical director of Fromer Eye Centers. ..."Fromer said the press-on prism, which can also be used to treat muscle weakness in the eye, 'helps bring images into focus.'"A Manhattan eye doctor who refused to give his name agreed that double vision was 'the only reason' for Clinton to be wearing the stick-on."

Copyright 2016 NPR. To see more, visit http://www.npr.org/.