In a previous communication,1 the reaction time of the normal pupil was established by cinematographic means. Briefly, it was found that when light is flashed on a normal eye that is accommodated for the dark, there occurs a latent period of 0.1875 second before the pupil begins to contract. Then there follows a rapid primary contraction for 0.4365 second at the rate of 5.48 mm. per second. This is succeeded by a secondary contraction of 0.3125 second at the slower rate of 1.34 mm. per second. These experiments were conducted on normal young persons, an 8 ampere arc light being used for illumination, and the pupillary play being recorded by a spring-driven cinematographic camera of constant speed. The films thus obtained were projected on a screen, frame by frame, and the pupillary diameters measured in the projected pictures. The relationship to the corneal diameter, which was measured in the
GRADLE HS, ACKERMAN W. THE REACTION TIME OF THE NORMAL PUPIL: SECOND COMMUNICATION. JAMA. 1932;99(16):1334–1336. doi:10.1001/jama.1932.02740680030008
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