To the Editor.—
I appreciate the letters of Drs Love and Davenport, which allow me to correct an error and expand further on the topic. They both correctly point out that it is the failure of the dilated pupil to constrict within 30 minutes after instillation of pilocarpine that proves cholinergic blockade of the iris sphincter. However, if the interval between scopolamine contact and pilocarpine administration is prolonged, a muted response with partial constriction may be seen. There is another caveat as well. Patients with the sudden onset of high intraocular pressure and iris sphincter ischemia due to acute narrow-angle glaucoma may also fail to respond to pilocarpine. Once the intraocular pressure has been reduced, the pupil will constrict to pilocarpine.1 In all cases, pilocarpine should be instilled in both eyes, with the normal eye serving as a control, where prompt and extensive constriction should occur.Regarding the sequence
Price BH. Anisocoria From Scopolamine Patches. JAMA. 1985;254(13):1720–1721. doi:10.1001/jama.1985.03360130052016
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