Certified Surgical Technologist (CST) Practice Exam

What enzyme is used to soften the zonules of the lens before cataract surgery?

1. Atropine sulfate

2. Alpha-chymotrypsin

3. Acetylcholine chloride

4. Pilocarpine hydrochloride

The correct answer is: Alpha-chymotrypsin

The use of alpha-chymotrypsin to soften the zonules of the lens prior to cataract surgery is based on its enzymatic action. Alpha-chymotrypsin is a proteolytic enzyme that specifically breaks down proteins, including those found in the zonules, which are the fibrous strands connecting the lens to the ciliary body in the eye. By softening these structures, alpha-chymotrypsin facilitates the surgical removal of the lens during cataract surgery, making the procedure smoother and potentially reducing trauma to surrounding tissues. Atropine sulfate is primarily used to dilate the pupil and immobilize the lens during surgery, not to soften zonules. Acetylcholine chloride functions as a miotic agent, constricting the pupil, which is contrary to the desired effect before cataract surgery. Pilocarpine hydrochloride is also a miotic that decreases intraocular pressure but does not play a role in softening the zonules. Thus, the enzymatic action of alpha-chymotrypsin is specifically helpful in the context of preparing the eye for cataract extraction by addressing the zonules directly.