Visual pathway: cortical blindness: 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 · Visual pathway: cortical blindness

Sample item

A patient after bilateral occipital infarcts is blind but has normal pupillary reactions and a normal fundus. What explains the normal pupillary response?

AThe pupil is controlled by the cerebellumBThe pupillary light reflex pathway leaves the optic tract before the lateral geniculate bodyCThe sympathetic pathway compensatesDThe pupil is controlled by the occipital cortex

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

The answer and the reasoning

B. The pupillary light reflex pathway leaves the optic tract before the lateral geniculate body

Pupillary fibres leave the tract to the pretectal nuclei before the lateral geniculate body, so lesions beyond this point leave reactions intact. The patient may deny blindness, called Anton syndrome.

Option by option

A. The pupil is controlled by the cerebellum
The cerebellum is not involved.
B. The pupillary light reflex pathway leaves the optic tract before the lateral geniculate body (correct)
Correct. The reflex arc bypasses the geniculate and cortex.
C. The sympathetic pathway compensates
Sympathetic input does not produce the light reflex.
D. The pupil is controlled by the occipital cortex
The cortex does not control the light reflex.

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.

Questions about this Ophthalmology question

What is the answer to this Ophthalmology question?

The best answer is B, The pupillary light reflex pathway leaves the optic tract before the lateral geniculate body. Pupillary fibres leave the tract to the pretectal nuclei before the lateral geniculate body, so lesions beyond this point leave reactions intact.

Why is "The pupil is controlled by the cerebellum" not the answer?

The cerebellum is not involved.

Why is "The sympathetic pathway compensates" not the answer?

Sympathetic input does not produce the light reflex.

Why is "The pupil is controlled by the occipital cortex" not the answer?

The cortex does not control the light reflex.

What concept does this question test?

It tests Visual pathway: cortical blindness in Ophthalmology. The patient may deny blindness, called Anton syndrome.

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 Visual pathway: cortical blindness?

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.