PIGMENT MAY HELP VISION — The same chemical that gives you that golden tan from the summer sun may also help you to see. The brown pigment, melanin, may take part in controlling the messages sent from the eye to the brain, Lieut. Raymond J. Sever, U.S. Navy, told the American Chemical Society in Atlantic City. Melanin is found in the retina, the light sensitive part of the eye. Here, the energy of light is picked up and changed into nerve impulses. It is not known how this is done, he said. When melanin, extracted from cows’ eyes, was exposed to light, there was a rapid appearance of free radicals — high energy particles capable of creating an electric charge.... These free radicals could produce an electrical voltage across the retina, thus controlling the nerve impulses from the eye to the brain, he suggested.