The pupillary light reflex. 1. Age-dependent and age-independent parameters in normal subjects.

A hundred and three normal subjects (14-75 years old) were examined with a modified infrared TV videopupillometer that had previously been developed. Maximal pupillary diameter (p less than 0.00001), pupillary diameter in percent of iris diameter (p less than 0.00001), maximal pupillary area (p less than 0.00001), latency time of the light reflex (p less than 0.00001), maximal contraction velocity (p less than 0.00002), contraction velocity at 1 s (p less than 0.00001) and dilatation velocity at 6 s (p less than 0.0001) are strongly age dependent. A statistical formula is given to allow the calculation of the exact percentile for every parameter. Parameters which are age independent if they are expressed in percent of the maximal pupillary area are contraction velocity at 1 s (r = 0.042, p = 0.68) and dilatation velocity at 6 s (r = -0.150, p = 0.13). They can be used if age-matched study groups are not available. Furthermore, it is shown that most parameters of the pupillary light reflex correlate significantly with each other. The highest correlations are found with the maximal pupillary area. Differences between sexes are not evident. It is thought that this infrared videopupillometry and the given data base are useful for further clinical studies to investigate the autonomic nervous system.