Hello doctor,
Hello. I passed carefully through your question and reviewed your uploaded MRI (magnetic resonance imaging) report. (attachment removed to protect patient identity).  I would explain that these MRI findings (T2 hyperintensity in the optic nerve and the optic chiasm) are indicative of optic nerve inflammation (neuritis), which could be related to Ethambutol adverse effects. The troubles with vision are a clinical sign of optic neuritis too. So, considering that there is a correlation between radiological and clinical findings, I would conclude about optic neuritis and would recommend to stop Ethambutol as soon as possible in order to avoid possible blindness. I hope this helps.