Neuro-ophthalmology and pupils: dense cataract and afferent defect: 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 and pupils: dense cataract and afferent defect

Sample item

A 70-year-old has a mature cataract in the right eye with 6/60 vision and a visible relative afferent pupillary defect on swinging flashlight testing. How should the finding be interpreted?

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

The answer and the reasoning

A. A coexisting retinal or optic nerve disorder is likely

A cataract, even dense, scatters light but still transmits enough, so it causes little or no afferent pupillary defect. An obvious RAPD therefore suggests additional retinal or optic nerve disease that may limit visual recovery after surgery. Evaluation with B-scan, OCT or visual fields may be required.

Option by option

  • A. A coexisting retinal or optic nerve disorder is likely (correct)

    Correct. A cataract alone rarely causes a clear RAPD, so look for retinal or optic nerve disease.

  • B. It indicates a third nerve palsy

    An oculomotor palsy affects the efferent pathway and would not give an afferent defect.

  • C. It confirms a phacomorphic angle closure

    Angle closure may cause a sluggish pupil but does not define a relative afferent defect.

  • D. It is the normal effect of the dense lens opacity

    A dense lens opacity does not normally produce a relative afferent defect.

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 A, A coexisting retinal or optic nerve disorder is likely. A cataract, even dense, scatters light but still transmits enough, so it causes little or no afferent pupillary defect.

Why is "It indicates a third nerve palsy" not the answer?

An oculomotor palsy affects the efferent pathway and would not give an afferent defect.

Why is "It confirms a phacomorphic angle closure" not the answer?

Angle closure may cause a sluggish pupil but does not define a relative afferent defect.

Why is "It is the normal effect of the dense lens opacity" not the answer?

A dense lens opacity does not normally produce a relative afferent defect.

What concept does this question test?

It tests Neuro-ophthalmology and pupils: dense cataract and afferent defect in Ophthalmology. An obvious RAPD therefore suggests additional retinal or optic nerve disease that may limit visual recovery after surgery. Evaluation with B-scan, OCT or visual fields may be required.

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 and pupils: dense cataract and afferent defect?

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.