## Core Concept
Ethambutol is an antitubercular medication used in the treatment of tuberculosis. It belongs to the class of drugs known as diamines and works by inhibiting the synthesis of the cell wall of Mycobacterium tuberculosis. One of its notable side effects is related to vision.

## Why the Correct Answer is Right
The correct answer, optic neuritis leading to visual disturbances, is a well-known side effect of ethambutol. This condition can result in decreased visual acuity and even color blindness. The mechanism behind ethambutol-induced optic neuritis is not entirely understood, but it is thought to be related to the toxic effect of the drug on the optic nerve. This side effect is particularly concerning in children because it can be difficult for them to report subtle changes in their vision.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is blank and cannot be evaluated.
- **Option B:** This option is blank and cannot be evaluated.
- **Option D:** This option is blank and cannot be evaluated.

## Clinical Pearl / High-Yield Fact
A key clinical consideration with ethambutol use, especially in children, is the need for regular monitoring of visual acuity. This is crucial because children may not be able to report early symptoms of visual disturbances. The risk of optic neuritis necessitates caution and careful follow-up when using ethambutol, particularly in pediatric patients.

## Correct Answer: C. Optic neuritis leading to visual disturbances