The state of focus of the eye in dim light and in total darkness was investigated by photographing the Purkinje images of a double aperture placed over a high speed flash lamp. Measurement of the photographed images showed that all subjects, when viewing a dim scene, remained focused for far vision. By subjective test, however, these subjects were myopic under the same conditions of dim light. The experimental results thus favor the theory that “night myopia” is a result of the aberrations of the eye and is not due to accommodation. The flash photographs taken in total darkness showed that three subjects remained focused for far vision; the fourth subject sometimes accommodated, by amounts varying between 0.5 and 1.5 diopter.
© 1953 Optical Society of AmericaFull Article | PDF Article