Glaucoma: perimetry global indices: 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 · Glaucoma: perimetry global indices

Sample item

A patient with glaucoma also has a developing cataract. On automated static perimetry, which global index best reflects localised glaucomatous loss while being relatively unaffected by the diffuse depression from lens opacity?

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

The answer and the reasoning

D. Pattern standard deviation

Mean deviation falls with both diffuse and localised loss, so a cataract lowers it. Pattern standard deviation measures irregularity of the field relative to the age-matched normal hill, so it rises mainly with focal defects. Fixation losses and false responses only describe test reliability.

Option by option

  • A. False-positive rate

    False-positive rate is a reliability index of trigger-happy responses and does not measure field damage.

  • B. Mean deviation

    Mean deviation reflects the average loss, so a cataract depresses it and it cannot isolate focal glaucomatous loss.

  • C. Fixation loss rate

    Fixation loss rate is a reliability index and does not measure field damage.

  • D. Pattern standard deviation (correct)

    Correct. Pattern standard deviation rises with focal, uneven loss and is relatively insensitive to uniform depression from media opacity.

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, Pattern standard deviation. Mean deviation falls with both diffuse and localised loss, so a cataract lowers it.

Why is "False-positive rate" not the answer?

False-positive rate is a reliability index of trigger-happy responses and does not measure field damage.

Why is "Mean deviation" not the answer?

Mean deviation reflects the average loss, so a cataract depresses it and it cannot isolate focal glaucomatous loss.

Why is "Fixation loss rate" not the answer?

Fixation loss rate is a reliability index and does not measure field damage.

What concept does this question test?

It tests Glaucoma: perimetry global indices in Ophthalmology. Pattern standard deviation measures irregularity of the field relative to the age-matched normal hill, so it rises mainly with focal defects. Fixation losses and false responses only describe test reliability.

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 Glaucoma: perimetry global indices?

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.