Tonic pupil: a simple screening test.

The tonic pupil has a typical appearance and characteristic reactions to both light and the near reflex. Testing with Mecholyl (methacholine) is not possible since the drug is no longer manufactured. The reactions of a group of 25 patients with tonic pupil were studied using dilute pilocarpine, and compared with the pupil responses of a separate control group. We found that concentrations of 0.2% pilocarpine produced too many false-positive reactions in the control group and that 0.05% pilocarpine produced an insufficient response. The 0.1% concentration seemed suitable for ordinary clinical examinations and is recommended for pharmacologic confirmation of the diagnosis of tonic (Adie's) pupil.