Page:Latency of Pupillary Reflex to Light Stimulation and Its Relationship to Aging.djvu/3



is concerned with the latency period of the pupillary contraction to light and the relationship of this latency period to aging. Some findings on pupillary latency periods related to light intensity, as well as to myopes with mydriasis and to an individual with nerve conduction disease, are described.

Analysis of the normal light reflex into its several components of speed and amplitude has been attempted for over 100 years. Techniques of pupillary measurement have been varied and have included: 1) entopic observation in which the observer subjectively measured his own pupillary diameter or reactions; 2) direct observation and measurement of the subject's pupil by ruler, scales, circles, holes, etc., 3) photographic techniques, and, 4) pupillographs using various cinematographic or electronic devices. In 1956, Lowenstein and Loewenfeld developed the Electronic Pupillograph which was the prototype of the instrument used in this study. A typical curve of the signal output of the Electronic Puplllograph is shown in Figure 1.

In 1845, Listing with entopic observations determined that the latency period for pupillary contraction was about 0.4 second when the eye was opened suddenly, and that the contraction movement lasted about 0.5 second. Since then, numerous investigators have made determinations of the latency period and