Ischemic Optic Neuropathy Caused by Iron Deficiency Anemia Accompanied by Ethambutol-induced Toxic Optic Neuropathy

ABSTRACT

Purpose@#To report a case of ischemic optic neuropathy caused by iron deficiency anemia (IDA) accompanied by ethambutol-induced toxic optic neuropathy.Case summary: A 64-year-old female patient presented with declining visual acuity. Four months prior, she had been taking ethambutol daily for tuberculosis. Corrected visual acuity was 0.3 in both eyes and a central visual field defect was revealed in visual field tests. In the color vision test, the right eye scored three and the left eye scored two. Ethambutol was stopped immediately under suspicion of toxic optic neuropathy; however, the corrected visual acuity gradually worsened to 0.05 in the right eye and the finger count was 50 cm in the left eye. The patient’s blood test showed signs of IDA. After 5 months of IDA treatment, the blood test results returned to the normal range and corrected visual acuity improved to 0.5 in both eyes. However, focal atrophy of the ganglion cell-inner plexiform layer was observed, requiring close monitoring of optical coherence tomography findings. @*Conclusions@#Ischemic optic neuropathy due to IDA may occur in a short period of time and may be difficult to diagnose if accompanied by ethambutol-induced toxic optic neuropathy. In the case of patients with progressive vision loss, prompt diagnosis and careful monitoring in follow-up evaluations are required.