My first favorite movie!

Synopsis: Dr. Xavier develops eyedrops intended to increase the range of human vision, allowing one to see beyond the "visible" spectrum into the ultraviolet and x-ray wavelengths and beyond. Believing that testing on animals and volunteers will produce uselessly subjective observations, he begins testing the drops on himself.

Initially, Xavier discovers that he can see though people's clothing, and he uses his vision to save a young girl whose medical problem was misdiagnosed. Over time and with continued use of the drops, Xavier's visual capacity increases and his ability to control it decreases until he can no longer see the world in human terms, but only in forms of lights and textures that his brain is unable to fully comprehend. His behavior becomes increasingly erratic, and Xavier's associates assume that he is going insane. (more from Wikipedia)