Physiology: blood-retinal barrier: 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: blood-retinal barrier

Sample item

The outer blood-retinal barrier is formed by which structure?

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

The answer and the reasoning

C. Tight junctions between retinal pigment epithelial cells

The outer barrier is formed by the zonula occludens between RPE cells, and the inner barrier by tight junctions of retinal capillary endothelium. Breakdown of the outer barrier gives serous retinal detachment as in central serous chorioretinopathy. Breakdown of the inner barrier gives leakage seen in diabetic macular oedema.

Option by option

  • A. Muller cell end feet at the inner limiting membrane

    Muller cell end feet form the inner limiting membrane but not a tight junction barrier.

  • B. Tight junctions of retinal capillary endothelium

    This is the inner barrier, not the outer.

  • C. Tight junctions between retinal pigment epithelial cells (correct)

    Correct. RPE tight junctions form the outer blood-retinal barrier.

  • D. Bruch membrane

    Bruch membrane is an extracellular layer and not the barrier.

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, Tight junctions between retinal pigment epithelial cells. The outer barrier is formed by the zonula occludens between RPE cells, and the inner barrier by tight junctions of retinal capillary endothelium.

Why is "Muller cell end feet at the inner limiting membrane" not the answer?

Muller cell end feet form the inner limiting membrane but not a tight junction barrier.

Why is "Tight junctions of retinal capillary endothelium" not the answer?

This is the inner barrier, not the outer.

Why is "Bruch membrane" not the answer?

Bruch membrane is an extracellular layer and not the barrier.

What concept does this question test?

It tests Physiology: blood-retinal barrier in Ophthalmology. Breakdown of the outer barrier gives serous retinal detachment as in central serous chorioretinopathy. Breakdown of the inner barrier gives leakage seen in diabetic macular oedema.

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 Physiology: blood-retinal barrier?

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.