Physiology: rod distribution: 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 · Physiology: rod distribution

Sample item

Rod photoreceptors reach their peak density at about how far from the fovea?

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

The answer and the reasoning

D. About 20 degrees

Rod density peaks in a ring around 20 degrees (about 5 to 6 mm) from the fovea. Rods mediate scotopic vision and peripheral fields. The optic disc has no photoreceptors and forms the blind spot.

Option by option

  • A. At the ora serrata

    Rod density falls towards the ora serrata.

  • B. At the foveola

    The foveola has no rods.

  • C. At the optic disc

    The disc has no photoreceptors at all.

  • D. About 20 degrees (correct)

    Correct. Rods are most dense about 20 degrees from the fovea.

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, About 20 degrees. Rod density peaks in a ring around 20 degrees (about 5 to 6 mm) from the fovea.

Why is "At the ora serrata" not the answer?

Rod density falls towards the ora serrata.

Why is "At the foveola" not the answer?

The foveola has no rods.

Why is "At the optic disc" not the answer?

The disc has no photoreceptors at all.

What concept does this question test?

It tests Physiology: rod distribution in Ophthalmology. Rods mediate scotopic vision and peripheral fields. The optic disc has no photoreceptors and forms the blind spot.

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 Physiology: rod distribution?

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.