Antimuscarinic drugs are widely used in ophthalmology to produce mydriasis and cycloplegia. These actions permit an accurate determination of the refractive state of the eye, and the antimuscarinics are also useful in treating specific ocular diseases and for the treatment of patients following iridectomy.
Atropine, scopolamine, cyclopentolate (Cyclogyl, AK-Pentolate, and others) and tropicamide (Mydriacyl, Tropicacyl, and others) are among the antimuscarinic drugs used in ophthalmology. All of these agents are tertiary amines that reach the iris and ciliary body after topical application to the eye. Systemic absorption of these drugs from the conjunctival sac is minimal, but significant absorption and toxicity can occur if the an-timuscarinic drugs come into contact with the nasal and pharyngeal mucosa via the nasolacrimal duct. To minimize this possibility, pressure should be applied to the lacrimal sac for a few minutes after topical application of muscarinic blockers.
The mydriatic and cycloplegic actions of atropine and scopolamine can persist for a week after topical application to the eye. Shorter-acting drugs, such as cy-clopentolate and tropicamide, are now favored for this application because complete recovery of accommodation occurs within 6 to 24 hours and 2 to 6 hours, respectively.
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