Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What classification of drugs leads to contraction of the iris sphincter and ciliary body?

1. Anticholinergic agents

2. Cholinergic agents

3. Sympathomimetic agents

4. Beta-blockers

The correct answer is: Cholinergic agents

Cholinergic agents are drugs that mimic the action of acetylcholine, a neurotransmitter involved in several physiological processes, including those in the eye. When cholinergic agents are administered, they activate muscarinic receptors in the eye, leading to the contraction of the iris sphincter muscle. This contraction results in miosis, or pupil constriction. Additionally, cholinergic agents stimulate the ciliary body, resulting in contraction of the ciliary muscle. This muscle contraction facilitates accommodation (the ability to focus on near objects) and can also enhance aqueous humor drainage by pulling on the trabecular meshwork, which may reduce intraocular pressure. The effects of cholinergic agents are particularly useful in the management of certain eye conditions, such as glaucoma, as they can help reduce intraocular pressure and allow better outflow of the aqueous humor. Therefore, the action of cholinergic agents in leading to the contraction of both the iris sphincter and the ciliary body is well-established in ophthalmic pharmacology.