Flying spot TV ophthalmoscope

We have designed a recording ophthalmoscope which requires substantially less light than conventional ophthalmoscopes or fundus cameras. A laser beam of <100-microW total power provides the flying spot on the subject's retina, allowing an inversion of the usual division of the pupil: only the central half-millimeter is needed for illumination, and the remaining 50 mm(2) are used for light collection. No optical image of the retina is formed, but a photomultiplier tube in a pupillary conjugate plane provides video signals to a TV monitor, where an image appears. A simple analysis explains the gain in sensitivity. Various manipulations of the image are described, some of which are uniquely possible with this system.