Neuro-ophthalmology and pupils: Hess chart: 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: Hess chart

Sample item

Hess charting is done in a patient with a recent paralytic squint to analyse ocular movement. How is the paretic eye recognised on the chart?

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

The answer and the reasoning

C. Its plotted field is smaller

In paralytic squint, the paretic eye plots a smaller field because its movements are restricted, while the sound eye shows a larger field from overaction of the yoke muscle (Hering's law). In concomitant squint the two fields are of normal size but displaced.

Option by option

  • A. Only the fixing eye is plotted

    Both eyes are charted alternately, one while fixing and the other while fixing in turn.

  • B. Its plotted field is larger

    The larger field belongs to the eye with secondary overaction, the non-paretic eye.

  • C. Its plotted field is smaller (correct)

    Correct. The smaller field belongs to the paretic eye.

  • D. Both fields are equal but displaced

    Equal fields that are displaced in position characterise concomitant squint.

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 C, Its plotted field is smaller. In paralytic squint, the paretic eye plots a smaller field because its movements are restricted, while the sound eye shows a larger field from overaction of the yoke muscle (Hering's law).

Why is "Only the fixing eye is plotted" not the answer?

Both eyes are charted alternately, one while fixing and the other while fixing in turn.

Why is "Its plotted field is larger" not the answer?

The larger field belongs to the eye with secondary overaction, the non-paretic eye.

Why is "Both fields are equal but displaced" not the answer?

Equal fields that are displaced in position characterise concomitant squint.

What concept does this question test?

It tests Neuro-ophthalmology and pupils: Hess chart in Ophthalmology. In concomitant squint the two fields are of normal size but displaced.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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: Hess chart?

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.