Assessment of unilateral afferent pupillary defects by pupillography

A pupillographic technique, an adaptation of the swinging light test, is described for the measurement of unilateral afferent pupillary defects. In normal persons it yielded accurate, reproducible estimates of the magnitude of artificial afferent defects made with neutral filters of 1 to 4 log units density. In 15 studies on 8 patients with unilateral optic neuritis and 2 with unilateral compressive lesions the measured afferent pupillary defects correlated closely with both visual acuity and visual threshold deficits. Measurement of the pupillary defect underestimated severe degrees of impairment revealed by visual threshold determination. Discrepancies between pupillary defect and visual acuity were observed in the 2 patients with compressive lesions and in 1 patient who had a central scotoma 4 months after an attack of optic neuritis.