## **Core Concept**
The question pertains to the clinical presentation of a patient with asymmetric optic disc changes, specifically swelling in one eye and atrophy in the other. This presentation can be indicative of a condition affecting the optic nerves or the surrounding structures. The key concept here involves understanding the causes of unilateral or asymmetric optic disc swelling and atrophy.

## **Why the Correct Answer is Right**
The correct answer, **Foster-Kennedy syndrome**, is a condition characterized by ipsilateral optic atrophy and contralateral papilledema. This syndrome typically results from a space-occupying lesion, such as a tumor (e.g., meningioma or glioma), that compresses the optic nerve on one side, leading to atrophy, and also causes increased intracranial pressure leading to papilledema (optic disc swelling) in the other eye. This matches the description given: optic disc swelling in the right eye (papilledema) and optic atrophy in the left eye.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Not provided, but any incorrect option would not accurately describe the clinical scenario of ipsilateral optic atrophy and contralateral papilledema.
- **Option B:** Similarly, without specifics, any option not aligning with the pathophysiology or clinical presentation of Foster-Kennedy syndrome would be incorrect.
- **Option C:** Again, would not match the syndrome's characteristics.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is that Foster-Kennedy syndrome is a rare condition but a classic cause of asymmetric optic disc changes. It often results from a frontal lobe tumor compressing one optic nerve and causing increased intracranial pressure. Remembering this association can help in quickly identifying the likely diagnosis in similar clinical scenarios.

## **Correct Answer:** D. Foster-Kennedy syndrome.