Cloning and characterization of x - 1: a developmentally regulated member of a novel class of the io

A device for automatically mapping the visual field of a subject includes a concave, generally hemispherical viewing screen, with a plurality of light-conducting fibers extending thereto from the convex side of the screen. The other ends of the light conducting fibers are joined to a light distribution board which includes a pivot supporting a scanning arm. The scanning arm includes a light conducting tube which is adapted to direct a beam of light into individual ends of the light conducting fibers, and the distribution board includes a printed circuit which is used to determine which light conducting fiber is being illuminated. The scanning arm itself is illuminated by a light module which includes an incandescent bulb powered by a regulated source, a continuously variable neutral density wedge, a color filter wheel, and a noiseless shutter. The light module also includes a light thief which samples the illumination provided to the scanning arm to determine the intensity thereof. Photoelectric means are provided to measure the actual background illumination of the viewing screen, and eye monitor means are provided to determine that the eye of the subject is open and is fixated on the center of the viewing screen.