Complications and emergencies: perioperative monocular visual loss: practice question

A Anaesthesia 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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Anaesthesia · Complications and emergencies: perioperative monocular visual loss

Sample item

A patient wakes after a 7-hour prone spinal fusion with painless loss of vision in the right eye only. The right periorbital area is swollen and bruised from resting on the headrest, and the pupil is dilated and poorly reactive. What is the most likely mechanism?

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

The answer and the reasoning

C. External globe compression causing retinal artery occlusion

Pressure on the orbit in the prone position can raise intraocular pressure above retinal perfusion pressure and occlude the central retinal artery. The signs are unilateral painless blindness with periorbital swelling or bruising and a poorly reactive pupil. Eyes should be checked and kept free of pressure throughout prone surgery.

Option by option

  • A. Corneal abrasion from an unprotected eye

    A corneal abrasion causes a painful, gritty eye and blurred vision, not a dilated fixed pupil and blindness.

  • B. Cortical infarction in a watershed territory

    Cortical blindness is bilateral with preserved pupillary reactions and does not leave periorbital bruising.

  • C. External globe compression causing retinal artery occlusion (correct)

    Correct. A unilateral, painless deficit with orbital pressure marks points to retinal artery occlusion from direct compression.

  • D. Bilateral optic nerve ischaemia from hypotension and anaemia

    Ischaemic optic neuropathy from hypotension and anaemia is typically bilateral and not accompanied by signs of orbital pressure.

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 Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, External globe compression causing retinal artery occlusion. Pressure on the orbit in the prone position can raise intraocular pressure above retinal perfusion pressure and occlude the central retinal artery.

Why is "Corneal abrasion from an unprotected eye" not the answer?

A corneal abrasion causes a painful, gritty eye and blurred vision, not a dilated fixed pupil and blindness.

Why is "Cortical infarction in a watershed territory" not the answer?

Cortical blindness is bilateral with preserved pupillary reactions and does not leave periorbital bruising.

Why is "Bilateral optic nerve ischaemia from hypotension and anaemia" not the answer?

Ischaemic optic neuropathy from hypotension and anaemia is typically bilateral and not accompanied by signs of orbital pressure.

What concept does this question test?

It tests Complications and emergencies: perioperative monocular visual loss in Anaesthesia. The signs are unilateral painless blindness with periorbital swelling or bruising and a poorly reactive pupil. Eyes should be checked and kept free of pressure throughout prone surgery.

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 Complications and emergencies: perioperative monocular visual loss?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia 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.