Abstract
BACKGROUND: Veterinary antiparasitic drugs are widely used in countries and regions in which parasitic diseases are endemic, which leads to the risk of accidental ingestion and poisoning in humans. CASE PRESENTATION: A 40-year-old male patient with a history of cirrhosis sought medical attention on November 25, 2021, due to progressive vision loss. He had previously taken triclabendazole and bithionol and was diagnosed with toxic optic neuropathy on examination. Steroid, neurotonic, and high-pressure oxygen therapy were ineffective. CONCLUSIONS: Triclabendazole and bithionol have potential risk of optic neurotoxicity and should be considered for enhanced supervision and warning labels.