## **Core Concept**
Optic neuritis refers to inflammation of the optic nerve, which can lead to acute vision loss. This condition can be a side effect of certain medications, infections, or autoimmune diseases. In the context of pharmacology, specific drugs are known to cause optic neuritis as an adverse effect.

## **Why the Correct Answer is Right**
The correct answer, , is associated with ethambutol, a medication used primarily in the treatment of tuberculosis. Ethambutol can cause optic neuritis, leading to visual disturbances, including decreased visual acuity and even blindness. This side effect is thought to be related to the drug's toxic effect on the optic nerve. The risk of optic neuritis increases with higher doses and prolonged use of ethambutol.

## **Why Each Wrong Option is Incorrect**
- **Option A:** is not commonly associated with optic neuritis as a side effect.
- **Option B:** does not have a well-documented association with optic neuritis.
- **Option D:** is not typically linked with optic neuritis.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that ethambutol-induced optic neuritis is dose-dependent and can be irreversible. Patients on ethambutol should have regular monitoring of their visual acuity and color vision. A classic clinical correlation is that ethambutol toxicity often affects the optic nerve's ability to transmit color information, leading to difficulties in distinguishing between red and green.

## **Correct Answer:** . Ethambutol