Autonomic: atropine contraindications: practice question

A Pharmacology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pharmacology · Autonomic: atropine contraindications

Sample item

An elderly man with a shallow anterior chamber is given atropine as pre-anaesthetic medication and soon complains of severe eye pain and haloes. Why did atropine cause this?

AStimulation of ciliary muscle contraction opened the trabecular meshworkBMydriasis narrowed the iridocorneal angle and impeded aqueous drainage, precipitating angle-closureCConstriction of the pupil blocked outflowDCycloplegia lowered intraocular pressure and caused retinal detachment

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

B. Mydriasis narrowed the iridocorneal angle and impeded aqueous drainage, precipitating angle-closure

Antimuscarinics dilate the pupil, and in an anatomically narrow angle the thickened peripheral iris obstructs aqueous outflow, raising intraocular pressure acutely. Atropine is therefore avoided in angle-closure glaucoma, along with caution in prostatic hyperplasia.

Option by option

A. Stimulation of ciliary muscle contraction opened the trabecular meshwork
Ciliary contraction is a cholinergic effect that atropine blocks.
B. Mydriasis narrowed the iridocorneal angle and impeded aqueous drainage, precipitating angle-closure (correct)
Correct. Mydriasis can precipitate acute angle closure.
C. Constriction of the pupil blocked outflow
Atropine dilates, not constricts, the pupil.
D. Cycloplegia lowered intraocular pressure and caused retinal detachment
Cycloplegia does not lower pressure in this setting and is not the cause of the pain.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Pharmacology question

What is the answer to this Pharmacology question?

The best answer is B, Mydriasis narrowed the iridocorneal angle and impeded aqueous drainage, precipitating angle-closure. Antimuscarinics dilate the pupil, and in an anatomically narrow angle the thickened peripheral iris obstructs aqueous outflow, raising intraocular pressure acutely.

Why is "Stimulation of ciliary muscle contraction opened the trabecular meshw…" not the answer?

Ciliary contraction is a cholinergic effect that atropine blocks.

Why is "Constriction of the pupil blocked outflow" not the answer?

Atropine dilates, not constricts, the pupil.

Why is "Cycloplegia lowered intraocular pressure and caused retinal detachment" not the answer?

Cycloplegia does not lower pressure in this setting and is not the cause of the pain.

What concept does this question test?

It tests Autonomic: atropine contraindications in Pharmacology. Atropine is therefore avoided in angle-closure glaucoma, along with caution in prostatic hyperplasia.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Autonomic: atropine contraindications?

Learn drugs as classes, then the exception in each class that an examiner would pick. Then use the flashcards and the other Pharmacology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.