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To the Editor.
—I would like to take issue with Goldberg et al's interpretation of the topical 2.5% methacholine test, as given in their article entitled, "Ophthalmologic Studies of Familial Dysautonomia" (80:732-743 [Dec] 1968). Topical 2.5% methacholine instilled in an eye with an intact corneal epithelial barrier does not cause pupillary constriction in the normal eye, and does cause pupillary constriction in the parasympathetically denervated iris (Adie's).However, in patients with familial dysautonomia, the corneal epithelial barrier is not normal. The effect of both the alacrimia and the corneal anesthesia is to break down the corneal epithelial barrier, and, therefore, allow greater penetration of topical medications. Thus, 2.5% methacholine, if it penetrates easily, can cause constriction of the normally innervated pupil, and, therefore, cannot be unequivocably interpreted as indicating sphincter denervation in familial dysautonomia.This is borne out further by several facts:
The pupil in familial dysautonomia does