Which TB medication is associated with a potential decrease in vision?

Ethambutol is associated with a potential decrease in vision due to its known side effect of optic neuritis. This condition can lead to visual disturbances, including blurred vision, changes in color perception, and even vision loss in severe cases. Ethambutol acts by inhibiting the synthesis of the mycobacterial cell wall, which is crucial for the bacterium's survival and replication. While it is a highly effective drug used in the treatment of tuberculosis, it requires monitoring for ocular side effects, particularly in patients receiving the medication for an extended period. Regular eye exams are recommended for individuals on ethambutol to catch any adverse effects early.

In contrast, isoniazid, rifampin, and pyrazinamide do not have visual side effects as a common or well-documented risk. While they can cause other adverse effects impacting different organ systems, their association with visual deterioration is not significant, making ethambutol the correct answer in this context.