Anatomy: corneal endothelium regeneration: 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 · Anatomy: corneal endothelium regeneration

Sample item

A patient develops persistent corneal oedema after cataract surgery with a low endothelial cell count. Why is the oedema persistent?

AHuman corneal endothelial cells do not regenerate, and neighbours only spread to fill gapsBEndothelial cells divide only after age 60CEpithelial cells replace the endothelium after injuryDDescemet membrane actively pumps fluid and has failed

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

The answer and the reasoning

A. Human corneal endothelial cells do not regenerate, and neighbours only spread to fill gaps

Human endothelium is non-proliferative in vivo, so loss is made up by cell enlargement (polymegathism). Once density falls below a critical level of about 500 cells per mm2 the pump fails and the stroma swells. Endothelial keratoplasty is then needed.

Option by option

A. Human corneal endothelial cells do not regenerate, and neighbours only spread to fill gaps (correct)
Correct. Cell loss is permanent and the pump function eventually decompensates.
B. Endothelial cells divide only after age 60
Endothelial cells do not divide at any age in vivo.
C. Epithelial cells replace the endothelium after injury
Epithelium does not replace endothelium and cannot restore the pump.
D. Descemet membrane actively pumps fluid and has failed
Descemet membrane is acellular basement membrane and does not pump fluid.

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 A, Human corneal endothelial cells do not regenerate, and neighbours only spread to fill gaps. Human endothelium is non-proliferative in vivo, so loss is made up by cell enlargement (polymegathism).

Why is "Endothelial cells divide only after age 60" not the answer?

Endothelial cells do not divide at any age in vivo.

Why is "Epithelial cells replace the endothelium after injury" not the answer?

Epithelium does not replace endothelium and cannot restore the pump.

Why is "Descemet membrane actively pumps fluid and has failed" not the answer?

Descemet membrane is acellular basement membrane and does not pump fluid.

What concept does this question test?

It tests Anatomy: corneal endothelium regeneration in Ophthalmology. Once density falls below a critical level of about 500 cells per mm2 the pump fails and the stroma swells. Endothelial keratoplasty is then needed.

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 Anatomy: corneal endothelium regeneration?

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.