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

Step 1: Understanding the Question:
Pseudoexophthalmos (pseudoproptosis) means the eye looks like it is bulging forward, but the eyeball has not actually moved out of the orbit. True exophthalmos happens when a real mass or swelling behind the eye pushes the globe forward. We need to pick the option that produces a TRUE forward push of the eyeball, not just a false look of bulging.

Step 2: Key Formula or Approach:
Go through each option and ask: does this change the size of the eyeball or the position of the eyelid (a false look), or does it add a mass behind the eye that truly pushes it forward (true exophthalmos)?

Step 3: Detailed Explanation:
In high myopia, the eyeball itself grows longer than normal (axial length increases). This bigger globe makes the eye look like it is popping out, though it has not been pushed forward by any mass. This is a cause of pseudoexophthalmos.
In lid retraction (seen in thyroid eye disease), the upper eyelid sits higher than normal. More of the white of the eye and the cornea show, so the eye looks wider open and more prominent, again without any true forward push. This is also pseudoexophthalmos.
Facial nerve paralysis causes lagophthalmos, the eyelid cannot close fully over the eye. The eye stays partly open all the time, giving a staring, bulging look, though the globe itself has not moved forward. This too is pseudoexophthalmos.
An optic nerve glioma is a real tumour growing behind the eyeball, inside the orbit. As it grows, it physically pushes the eyeball forward out of the orbit. This is TRUE exophthalmos, one of the classic causes of true proptosis in children, not a false appearance.

Step 4: Final Answer:
Since high myopia, lid retraction, and facial nerve paralysis all give a false look of proptosis while the globe stays in place, and an optic nerve glioma actually pushes the eyeball forward, the condition that does NOT cause pseudoexophthalmos is optic nerve glioma.