Neuro-ophthalmology: third nerve palsy: practice question

A Ophthalmology 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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Ophthalmology · Neuro-ophthalmology: third nerve palsy

Sample item

A patient has ptosis, a down-and-out eye, diplopia, and a dilated poorly reactive pupil. What is the urgent concern?

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

The answer and the reasoning

C. Posterior communicating artery aneurysm

A painful or pupil-involving third-nerve palsy can result from compressive aneurysm and requires urgent neurovascular imaging. Ischemic palsies more often spare the pupil, but clinical evaluation is urgent.

Option by option

  • A. Blepharitis

    Blepharitis affects eyelid margins.

  • B. Isolated sixth nerve palsy only

    Sixth nerve palsy causes impaired abduction without ptosis and fixed dilated pupil.

  • C. Posterior communicating artery aneurysm (correct)

    Correct. Pupil involvement raises concern for compressive third-nerve injury.

  • D. Simple presbyopia

    Presbyopia affects near focus, not eye movements or pupil.

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.

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Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is C, Posterior communicating artery aneurysm. A painful or pupil-involving third-nerve palsy can result from compressive aneurysm and requires urgent neurovascular imaging.

Why is "Blepharitis" not the answer?

Blepharitis affects eyelid margins.

Why is "Isolated sixth nerve palsy only" not the answer?

Sixth nerve palsy causes impaired abduction without ptosis and fixed dilated pupil.

Why is "Simple presbyopia" not the answer?

Presbyopia affects near focus, not eye movements or pupil.

What concept does this question test?

It tests Neuro-ophthalmology: third nerve palsy in Ophthalmology. Ischemic palsies more often spare the pupil, but clinical evaluation is urgent.

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 Neuro-ophthalmology: third nerve palsy?

Group the red eye by what to examine and what the pupil does. Then use the flashcards and the other Ophthalmology 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.