The development of personal computer-based infrared video instruments has allowed pupillography to enter the clinical arena. Measuring pupil diameter for refractive surgery, distinguishing Horner syndrome from physiologic anisocoria, quantifying the relative afferent pupillary defect, and plotting visual fields by means of graded pupil constriction to focal light stimuli are recent applications in ophthalmology. Pupillography has also been used to determine sleepiness and autonomic effects of new pharmaceuticals.