Compare demyelinating optic neuropathy and compressive optic neuropathy in terms of onset, pain, and imaging features.

• A. Demyelinating optic neuropathy often presents acutely with pain on eye movement and may show optic nerve enhancement on MRI; compressive neuropathy tends to have progressive, painless loss and mass effect on imaging
• B. Demyelinating optic neuropathy painless; compressive neuropathy painful on movement
• C. Demyelinating optic neuropathy shows no MRI changes; compressive neuropathy shows enhancement
• D. Demyelinating optic neuropathy progressive painless; compressive acute with pain

Answer: (B)

A key distinction lies in how these two conditions typically begin, how they feel, and what imaging shows. Demyelinating optic neuropathy (optic neuritis) usually comes on suddenly or over a few days and is painful, especially with eye movements, because the inflamed optic nerve is tender as it moves. On MRI, you often see enhancement of the optic nerve, reflecting active inflammation and breakdown of the blood-nerve barrier.

Compressive optic neuropathy, from a surrounding mass or lesion pressing on the nerve, tends to progress gradually and is typically painless. Imaging reveals a mass effect— a lesion displacing or encasing the optic nerve, sometimes with bone remodeling or a distinct lesion, rather than primary nerve enhancement from inflammation.

So, the best match is acute onset with pain and possible nerve enhancement in the optic neuritis, versus a slowly progressive, painless course with a mass effect on imaging in compressive cases.