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Show / ournal of Clinical Nell",- ophthal", olos.~ 111l J: 57, 1991. Editorial Comment: Tonic Pupil This case report documents the occurrence of pupillary abnormalities in a patient with aberrant regeneration of the oculomotor nerve after acute oculomotor nerve paresis, probably caused by a posteriorly draining carotid- cavernous sinus fistula. The authors emphasize three findings: ( a) segmental constriction of the pupil during stimulation with light, ( b) constriction of portions of the pupil unreactive to light when the eye is moved in the field of gaze of one or more of the extraocular muscles innervated by the oculomotor nerve, and ( c) a " normal" response of the pupil to stimulation with near targets, Two of these abnormalities are commonly seen in patients with primary or secondary aberrant third nerve regeneration. Segmental constriction of the pupil to light stimulation is the rule rather than the exception after third nerve palsy. Some of the preganglionic fibers for pupillary light constriction make the appropriate synaptic connections in the ciliary ganglion, whereas others do not. Similarly, segmental constriction of the pupil during eccentric gaze is also common. Dr. Frank Walsh used to teach that the most common abnormalitiy seen in patients with aberrant regeneration of the oculomotor nerve was not eyelid retraction during eccentric gaze ( pseudo- Graefe sign), but constriction of a pupil that was nonreactive to light during eccentric eye movements in the field of action of one of the extraocular muscles innervated by the oculomotor 57 ' 0 1991 Raven Press, Ltd., New York nerve. When such patients were examined using slit- lamp biomicroscopy, virtually all of them had segmental, rather than generalized, pupillary constriction during eccentric gaze. The normal near response in this patient is quite interesting and worthy of emphasis, but it should not be confused with the near response in patients with a tonic pupil. The one pupillary abnormality that should always be present in a patient with a tonic pupil and that was not present in this patient is slow redilation to the resting state after constriction. This is a crucial sign, since it indicates postganglionic disease with supersensitivity to acetylcholine. I disagree with the authors' contention that "[ tonic re- dilatation] is frequently absent" in patients with tonic pupils. In my experience, patients with postganglionic light- near dissociation from damage to the ciliary ganglion or short posterior ciliary nerves invariably have tonic redilation. Thus, although I agree with Drs. Cox, Goldberg, and Rootman that this patient is particularly interesting because of the apparently normal near response in the face of incomplete pupillary constriction during both light stimulation and eccentric gaze, I object to describing the condition as a " tonic pupil," since there is nothing " tonic" about the process. Neil R. Miller, M. D. Baltimore, Maryland |