Question

Which one of the following conditions does NOT cause pseudoexophthalmos?

• A. High myopia
• B. Lid retraction
• C. Optic nerve glioma
• D. Facial nerve paralysis

Hint:

Think about which option truly pushes the eyeball forward instead of just changing how it looks.

Answer 1

The Correct Option is C

This question checks if you can tell apart a real forward push of the eyeball from a false look of bulging. Pseudoexophthalmos means the eye only appears to protrude, the globe has not actually moved out of its socket.

1. High myopia: A very long eyeball from myopia makes the eye look bigger and more prominent, but no mass pushes it forward. This is a false, pseudo picture.
2. Lid retraction: When the upper lid rides high, as in thyroid eye disease, more sclera and cornea are exposed, so the eye looks like it is bulging even though it sits in its normal place. Another pseudo picture.
3. Optic nerve glioma: This is a tumour growing right behind the eyeball inside the orbit. It takes up space and mechanically shoves the eyeball forward. That is genuine, true exophthalmos, not a pseudo finding.
4. Facial nerve paralysis: A weak facial nerve cannot close the eyelid properly (lagophthalmos), so the eye stays open and looks like it is staring or bulging, again without the globe moving forward. Pseudo picture.

Three of the four options only change how the eye looks without moving the globe, while the optic nerve glioma is a real space occupying mass that produces true proptosis.

Let's summarize:

• Pseudoexophthalmos looks like bulging but the eyeball stays in its normal position.
• True exophthalmos is caused by an actual orbital mass, like an optic nerve glioma, pushing the eye forward.

So the condition that does not cause pseudoexophthalmos is optic nerve glioma, since it causes true exophthalmos instead.