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Show !oumal of Cllllical Nellro-ophthalmology 7(3):144. 1987. Editorial Comment Near Reaction of the PupHs All too often we forget to check the near reaction of the pupils. We should school ourselves to do this brief test routinely-especially when the light reaction is seen to be poor. In patients like the one in the previous article, with profoundly impaired pupillomotor input and no relative afferent defect, the outflow to the iris sphincter can be tested with a near reaction or with forced lid closure. The difference between the light and near responses would be most dramatic in this patient if the light reaction were tested at the slit lamp (and therefore likely to be presented in the blind temporal field) and the near response tested in room light with an accommodative target. When the vision is poor, a firm "fly-on-the-nose" convergence effort will do the job. If the patient is not inclined to converge, try to get a "lid closure reaction": ask the patient to close his or her eyes firmly while you hold one eye open with both hands. The patient is asked to read the Snellen chart while all this is going on, and a strong "near effort" will often be summoned up from somewhere, and you can see the pupil constrict. 144 © 1987 Raven Press, Ltd., New York Is a light-near dissociation seen more frequently in chiasmal compression than in bilateral optic nerve disease? I am not aware that this has been systematically looked for. The temporal field carries more pupillomotor force than the nasal field, so a patient with bitemporal field loss would lose more light reaction than a patient with a comparable amount of field loss from glaucoma or ischemic optic neuropathy. And anyone who customarily checks the light reaction with the slit lamp from the temporal field would be more likely to find a light-near dissociation in a patient with a pituitary tumor. This case serves a reminder that, with lesions of the visual pathways, field loss and pupil loss walk hand in hand. H. Stanley Thompson, M.D. Department of Ophthalmology University Hospitals University of Iowa Iowa City, Iowa 52242 |