The new-look glasses sported by Secretary of State Hillary Clinton during Wednesday's testimony to the House and Senate Foreign Relations Committee were worn for health reasons.
Clinton's official spokesperson told CBS News that she will be wearing these glasses instead of her contacts for an undetermined period of time due to "lingering issues stemming from her concussion." He assured that the Secretary of State sees fine, and she thought a recent New York Magazine post detailing the different meanings of the faces she made when she was adjusting her glasses was funny once she saw it "crystal clearly."
Dr. Andrew Russman, a concussion and cerebrovascular expert from the Cleveland Clinic in Ohio, who is not involved in the secretary's care, speculated to CBSNews.com that the eyewear Clinton is sporting contains a Fresnel prism lens.
A Fresnel prism can help people who are having problems with converging their vision, or getting the images each eye detects to combine into one clear picture in their brain, Russman said. The prism allows the lens to refract light in a different way so the convergence point -- the point in front of your eyes where an object is seen as one image -- can be altered. However, if a person with normal vision wore glasses with a Fresnel prism, everything would be slightly askew, he added.
Clinton suffered a concussion on Dec. 13 after she fell and hit her head after fainting when sick with a stomach virus. Symptoms associated with a concussion may include persistent headaches, dizziness and problems with vision.
It is possible that Clinton was given the glasses because she was suffering from diplopia, when the brain sees two separate images at once, Dr. Sonu Ahluwalia, clinical chief of Orthopedic Surgery and head of the sports medicine division at Cedars Sinai Medical Center in Los Angeles, told CBSNews.com. Double vision can be caused by problems with the pathway from the eyes to the brain, which also include muscles and nerves. Ahluwalia has no role in Clinton's care.
"If both eyes are not targeted at the same image at the same time, the brain can't put it together," he said.
Russman said that vision problems following a concussion usually resolve on their own or with the aid of vestibular or visual rehabilitation, which involve exercises to help the patient deal with balance or vision problems. This can include putting the head in certain positions that have been known to make the person dizzy so they can get used to it or strengthening the eyes, forcing them to focus.
In more serious cases, surgery may be necessary.