What periodic diagnostic procedure should have monitored a patient's blurring of vision during DR-TB treatment?

During treatment for drug-resistant tuberculosis (DR-TB), monitoring for potential side effects of medications is critical, particularly regarding vision changes that may arise from certain drugs. The Snellen chart and Ishihara color vision test are specifically designed to assess visual acuity and color vision, respectively.

When patients report symptoms such as blurring of vision while on DR-TB treatment, it is vital to use the Snellen chart to measure visual sharpness and the Ishihara test to evaluate any changes in color perception. These tests can help identify toxic effects of medications, such as ethambutol, which is known to be associated with optic neuropathy, leading to vision changes.

The other choices do not directly address the issue of vision and are not suitable for monitoring these specific side effects. Blood chemistry examinations are important for assessing general health and kidney function, but they do not provide any visual assessments. Electrocardiography is useful for monitoring heart conditions and detecting drug-induced cardiac effects, and the Rinne and Weber tests are specifically for evaluating hearing, not vision.