Neuro-ophthalmology: 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

Sample item

A 60-year-old woman has a sudden severe headache followed by drooping of the right upper lid. The right eye is deviated down and out and the pupil is dilated and non-reactive. What is the most important cause to exclude urgently?

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

The answer and the reasoning

A. Posterior communicating artery aneurysm

A complete oculomotor palsy with pupil involvement suggests compression of the nerve, since pupillary fibres lie superficially. A posterior communicating artery aneurysm is the classic cause and risks subarachnoid haemorrhage, so urgent vascular imaging is needed.

Option by option

  • A. Posterior communicating artery aneurysm (correct)

    Compression by an aneurysm affects the superficial pupillary fibres and may rupture, so it must be excluded promptly.

  • B. Diabetic microvascular ischaemia of the nerve

    Diabetic ischaemia typically spares the pupil and is a lower-risk diagnosis.

  • C. Horner syndrome

    Horner syndrome causes a small pupil and mild ptosis, not a dilated pupil with eye deviation.

  • D. Myasthenia gravis

    Myasthenia does not affect the pupil and varies through the day.

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.

More Ophthalmology questions

Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is A, Posterior communicating artery aneurysm. A complete oculomotor palsy with pupil involvement suggests compression of the nerve, since pupillary fibres lie superficially.

Why is "Diabetic microvascular ischaemia of the nerve" not the answer?

Diabetic ischaemia typically spares the pupil and is a lower-risk diagnosis.

Why is "Horner syndrome" not the answer?

Horner syndrome causes a small pupil and mild ptosis, not a dilated pupil with eye deviation.

Why is "Myasthenia gravis" not the answer?

Myasthenia does not affect the pupil and varies through the day.

What concept does this question test?

It tests Neuro-ophthalmology in Ophthalmology. A posterior communicating artery aneurysm is the classic cause and risks subarachnoid haemorrhage, so urgent vascular imaging is needed.

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?

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.