Retina: limits of pneumatic retinopexy: 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 · Retina: limits of pneumatic retinopexy

Sample item

A surgeon plans to repair a rhegmatogenous detachment with an inferior retinal break by injecting an intraocular gas bubble. Why is this approach unsuitable for the inferior break?

AInferior breaks never respond to laser retinopexyBThe gas bubble rises and cannot tamponade a break in the lower retinaCGas absorbs too slowly in the lower vitreous cavityDThe bubble cannot be placed through the pars plana inferiorly

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

The answer and the reasoning

B. The gas bubble rises and cannot tamponade a break in the lower retina

A gas bubble is buoyant and floats to the highest point of the eye, so it can only press on breaks in the upper retina. This is why pneumatic retinopexy is limited to superior breaks, usually within the upper eight clock hours. Inferior breaks need a scleral buckle or vitrectomy.

Option by option

A. Inferior breaks never respond to laser retinopexy
Laser and cryotherapy can seal inferior breaks, so this is not the limiting factor.
B. The gas bubble rises and cannot tamponade a break in the lower retina (correct)
Correct. The gas bubble floats upward and cannot hold an inferior break against the pigment epithelium.
C. Gas absorbs too slowly in the lower vitreous cavity
Gas absorption rate does not depend on the position of the break.
D. The bubble cannot be placed through the pars plana inferiorly
Access through the pars plana is possible at any quadrant and is not the issue.

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 B, The gas bubble rises and cannot tamponade a break in the lower retina. A gas bubble is buoyant and floats to the highest point of the eye, so it can only press on breaks in the upper retina.

Why is "Inferior breaks never respond to laser retinopexy" not the answer?

Laser and cryotherapy can seal inferior breaks, so this is not the limiting factor.

Why is "Gas absorbs too slowly in the lower vitreous cavity" not the answer?

Gas absorption rate does not depend on the position of the break.

Why is "The bubble cannot be placed through the pars plana inferiorly" not the answer?

Access through the pars plana is possible at any quadrant and is not the issue.

What concept does this question test?

It tests Retina: limits of pneumatic retinopexy in Ophthalmology. This is why pneumatic retinopexy is limited to superior breaks, usually within the upper eight clock hours. Inferior breaks need a scleral buckle or vitrectomy.

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 Retina: limits of pneumatic retinopexy?

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.