A Consideration of the Horopter

The proctor Award Lecture

¹ Section of Biophysics, Mayo Clinic and Mayo Foundation , Rochester, Minn.

This discussion deals with the importance of the horopter as a functional concept associated with stereoscopic depth perception and the visual factors upon which it rests; the impossibility of defining strictly the ideal horopter because of vertical disparities; the experiments which prove that vertical disparities play no role in stereopsis; the concept of the longitudinal horopter as determined only by longitudinal sections of the retinas; the role of cyclofusional movements of the eyes in determining the shape of the horopter surface; the difficidties of determining the longitudinal horopter by experiment; the fact that we must rest with only a partial solution to the experimental problem; and, finally, the importance of the longitudinal horopter in egocentric spatial orientation and the probable stability of corresponding retinal points.