Optics, the eye, and the brain.

Optics began as a visual science, and the eye was the original optical instrument. Students of physiological optics, together with their clinical colleagues, were concerned mainly with the normal and pathological functioning of the eye as a receptor organ. In recent years, however, exciting developments have changed all that. Optics has taken off in many directions that have little immediate relation to the eye, such as x-ray astronomy, lasers, and photoacoustic spectroscopy. Vision research, in turn, has gone far beyond its sole preoccupation with the optics of the eye. Most exciting are new discoveries about the visual pathways and the specialization of individual brain cells for the processing of line orientation, stereoscopic depth, spatial frequency, motion, and color. Comparative studies reveal the functional architecture of the brain together with the genetically and chemically programmed cellular development that lays the groundwork for later modification by the visual environment. Stimulated by this neurophysiological progress, and by newly available optical concepts and techniques, visual scientists have greatly expanded their research beyond the traditional topics of physiological optics and color.