10:21 AM EST, January 25, 2013
Does Hillary Clinton have double vision?
The 65-year-old outgoing Secretary of State is wearing new glasses that show tiny lines visible on one lens.
It's called a "fresnel prism" and it's a stick-on panel often used to treat double vision.
"It helps me." Hillary says.
Clinton wore the glasses during her fiery testimony before the Senate this week.
Opthamologist Brian Campolattaro says the special lens brings double images into focus.
Campolattaro said, "When someone's seeing double, their images are either side-by-side or up-and-down from each other. By placing a fresnel prism, which bends the light, to a lense with a certain orientation, it allows the images to fuse again, allowing for single vision."
Double vision is a common side effect caused by a blood clot near the brain, like the one Hillary suffered last month.
"In Hillary's case, her significant head trauma probably caused damage, hopefully temporary, to the nerve that fees the muscles and moves the eye back and forth," said Campolattaro.