Indeed, Collie's two diagnosed concussions in 2010 packed a strong visual impact, with the thensecondyear receiver knocked flat on his back for about 10 minutes each time: in Week 9 at Philadelphia and again in Week 15 at home against Jacksonville. He left the Eagles game on a stretcher, but walked away on his own power against the Jaguars. In addition, he left a Week 11 game in the first quarter at New England that season, with concussionlike symptoms, a clear indication that he was not sufficiently recovered from the hit he took in Philly two weeks earlier..In contrast to ultrasonography, direct detection of light echoes is not possible with OCT, because the speed of light is much faster than the speed of sound; therefore, correlation techniques must be used. Early OCT systems were based on low coherence interferometry, a technique initially demonstrated by Sir Isaac Newton. With this technique, measurements are performed by use of a Michelsontype interferometer with a lowcoheren