Previous work dealing with the question of whether or not the eyes of small mammals are hyperopic has been restricted largely to the study of nocturnal animals such as the rat. In this study, refractive state of the eye of a small diurnal mammal, the ground squirrel, was measured by retinoscopy and from the electrophysiological response of retinal ganglion cells to grating targets. Both measurements show the squirrel to be emmetropic. We conclude that the refractive state of the eye is not a function of eye size per se, but rather a function of whether the animal is nocturnal or diurnal.
Received August 29, 1979.
* Neurophysiologist, Ph.D., Member of Faculty.
† Optometrist, Ph.D., Member of Faculty, F.A.A.O. Permanent address: School of Optmetry and Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
J. G. Sivak
School of Optometry and Department of Biology
University of Waterloo
Waterloo, Ontario, Canada N2L 3G1
© 1979 American Academy of Optometry