Certified Ophthalmic Medical Technologist (COMT) Practice Exam

What effect do parasympatholytics have on accommodation?

1. Increase accommodation

2. No effect on accommodation

3. Decrease accommodation

4. Stimulate ciliary muscle contraction

The correct answer is: Decrease accommodation

Parasympatholytics, also known as anticholinergics, inhibit the action of the neurotransmitter acetylcholine on the parasympathetic nervous system. In the context of accommodation, which is the process by which the eye adjusts its lens to focus on near objects, the ciliary muscle plays a crucial role. When the ciliary muscle contracts, it allows the lens to become more rounded, increasing its power to focus on close objects. By blocking the action of acetylcholine, parasympatholytics prevent the contraction of the ciliary muscle, leading to a decreased ability of the eye to accommodate. This results in difficulties in focusing on nearby objects, effectively decreasing accommodation. This pharmacological effect is why parasympatholytics are often used in medical settings to induce a condition called cycloplegia, where temporary paralysis of the ciliary muscle is desired for certain eye examinations or procedures. Hence, the correct answer captures the main physiological response of parasympatholytics as it pertains to accommodation.