Lens and cataract: complication of retrobulbar block: 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 · Lens and cataract: complication of retrobulbar block

Sample item

Within minutes of a retrobulbar injection, a patient becomes drowsy and apnoeic and the opposite pupil dilates. What has happened?

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

The answer and the reasoning

D. Brainstem anaesthesia through spread along the optic nerve sheath

Anaesthetic that tracks along the optic nerve dural sheath reaches the subarachnoid space and brainstem, causing drowsiness, apnoea and a contralateral dilated pupil. It needs airway support and ventilation until it wears off. Haemorrhage and perforation do not cause these systemic signs.

Option by option

  • A. Globe perforation

    Globe perforation causes pain, vitreous haemorrhage and a soft eye.

  • B. Retrobulbar haemorrhage

    Retrobulbar haemorrhage presents with tense proptosis, not apnoea and a contralateral pupil change.

  • C. Oculocardiac reflex

    The oculocardiac reflex produces bradycardia, not apnoea and contralateral pupil dilation.

  • D. Brainstem anaesthesia through spread along the optic nerve sheath (correct)

    Correct. Spread into the subarachnoid space produces brainstem anaesthesia.

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 D, Brainstem anaesthesia through spread along the optic nerve sheath. Anaesthetic that tracks along the optic nerve dural sheath reaches the subarachnoid space and brainstem, causing drowsiness, apnoea and a contralateral dilated pupil.

Why is "Globe perforation" not the answer?

Globe perforation causes pain, vitreous haemorrhage and a soft eye.

Why is "Retrobulbar haemorrhage" not the answer?

Retrobulbar haemorrhage presents with tense proptosis, not apnoea and a contralateral pupil change.

Why is "Oculocardiac reflex" not the answer?

The oculocardiac reflex produces bradycardia, not apnoea and contralateral pupil dilation.

What concept does this question test?

It tests Lens and cataract: complication of retrobulbar block in Ophthalmology. It needs airway support and ventilation until it wears off. Haemorrhage and perforation do not cause these systemic signs.

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 Lens and cataract: complication of retrobulbar block?

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.