Corneal sensitivity was assessed before and after applying atropine (0.5, 0.05, 0.005% w/v), pilocarpine (1.0, 0.1%), eserine (0.1, 0.01%) and potassium chloride (171mM). Atropine (0.5 − 0.005%) significantly depressed corneal sensitivity; parasympathomimetics, taken together, significantly increased sensitivity. Exposure to potassium chloride for 2 min had no effect on sensitivity, nor did it affect corneal sensation. These results are consistent with the hypothesis that epithelial acetylcholine is a neurotransmitter to the corneal nerves. We conclude, however, that the nerves may have only weak muscarinic propertie
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