## **Core Concept**
The question tests knowledge of adverse effects associated with specific medications, particularly those that affect vision. Visual field defects can be a side effect of various drugs, often related to their mechanism of action on the nervous system or specific ocular structures.

## **Why the Correct Answer is Right**
The correct answer, , is associated with visual field defects due to its mechanism of action. This drug can cause retinal toxicity, leading to visual disturbances, including visual field defects. The exact mechanism may involve interference with retinal pigment epithelial function or direct toxicity to photoreceptors.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is not commonly associated with visual field defects as a primary adverse effect. Its side effects profile may include other ocular issues but visual field defects are less commonly highlighted.
- **Option B:** does not have a well-documented association with visual field defects. Its adverse effects are more commonly related to other systems.
- **Option C:** might have ocular side effects but visual field defects are not a commonly emphasized adverse effect in its profile.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that certain medications can have significant ocular side effects, including visual field defects. is an example of a drug where monitoring for ocular toxicity, including visual field defects, is important during long-term treatment.

## **Correct Answer:** . Etambutol