Abstract

Sixty-two patients with diabetes mellitus were tested for the presence of parasympathetic denervation hypersensitivity of the iris using a 2% solution of methacholine. Fifty patients (81%) had a measurable miotic response compared with three (8%) of a group of 36 control subjects. An abnormal response was obtained from 17 (74%) of 23 patients with a clinical course of less than two years and 33 (85%) of 39 patients with a clinical course of longer duration. These findings corroborate other evidence of a high incidence of peripheral neuropathy appearing early in the clinical course of diabetes mellitus and extend the observations to the parasympathetic innervation of the iris. The methacholine test is a simple bedside method which is of potential value for establishing parasympathetic iris denervation of diverse aetiologies.