mydriatic and cycloplegic agent /mid′rē·at″ik/ [Gk, mydros + kyklos, circle, plege, stroke] , any one of several ophthalmic pharmaceutic preparations that dilate the pupil and paralyze the ocular muscles of accommodation. Mydriatics stimulate alpha adrenergic receptors or block cholinergic muscarinic receptors in the eye, temporarily paralyzing the iris sphincter muscle so that the pupil is maximally dilated. Cycloplegics block cholinergic muscarinic receptors, which temporarily paralyzes accommodation by relaxing the ciliary muscle to focus the lens for far vision. These drugs are used in diagnostic and refractive examination of the eye, before and after various procedures in eye surgery, in some tests for glaucoma, and in the treatment of anterior uveitis and certain kinds of glaucoma. Blurred vision, thirst, flushing, fever, and rash may occur. In children and elderly people ataxia, somnolence, delirium, and hallucination may occur but are rare. Among these drugs are atropine, cyclopentolate, homatropine, scopolamine, and tropicamide. They are prepared in solution for topical ophthalmic application.
