Improved photographic assessment of the pupils in the syndromes of Horner and Holmes-Adie.

The use of photographic methods to assess pupillary abnormalities has usually been restricted to the measurement of anisocoria in light and darkness. An improved, accurate and relatively inexpensive photographic technique of recording pupillary movement was described, and tested in normal individuals and in the Horner and Holmes-Adie syndromes. A modern SLR camera, preprogrammable for exposure frequency and interval, was used for serial flash-lit photographs of the eyes during the course of darkness and near vision/accommodation reflexes. Measurement of pupillary diameter from these photographs permitted graphs of pupillary reflexes to be drawn that resemble traces obtained by other authors, who used less readily available and cumbersome cinematographic and electronic infra-red pupillometric methods. In Horner's syndrome, the affected pupil was invariably smaller, and the anisocoria was more marked in bright light or darkness, depending on the individual. The rate of dark mydriasis was abnormally slow, and most effectively quantified by measuring the pupillary 'half opening time', which was the interval required for the initial 50% of dark-induced pupillary dilatation. Constriction of tonic pupils during near vision/accommodation in subjects with the Holmes-Adie syndrome was consistently slow, and these pupils also failed to dilate fully in darkness. The amplitude of the darkness and near vision accommodation reflexes correlated significantly. The diverse pathophysiological mechanisms implicated by these changes were discussed.