We considered the influence of ethambutol therapy for lung TBC on the visual function of patients. Cases of toxic optic neuropathy caused by ethambutol therapy in patients hospitalized in the Ophthalmic Clinic in Rijeka within 5 years were presented. Results of the treatment of toxic optic neuropathy caused by ethambutol are influenced by risk factors such as: diabetes mellitus, renal insufficiency, alcoholism and in our opinion, atherosclerosis and very old age.