A Case of Paralytic Strabismus after a Snake Bite on the Toe

Abstract

Purpose: To report a patient who developed paralytic strabismus despite receiving antivenom injection after a snake bite on his toe and recovered following treatment with anticholinesterase.Case Summary: A 25-year-old man with no previous ophthalmological or neurological illnesses presented to our emergency room after viper bite on the left toe. Because there were no other symptoms without localized pain, he was discharged after antivenom. The next day, he returned to the emergency room with sudden onset binocular diplopia. The alternate prism cover test showed 12 prism diopters of exotropia and 5 prism diopters of hypotropia at distance fixation in his left eye. The ocular movement test and Hess screen test revealed hypodeviation and limitation of the upper and medial gazes of the left eye. Under the impression of left oculomotor nerve palsy due to venom toxin, he underwent brain imaging to rule out the presence of another lesion and it was normal. Therefore, the patient was prescribed antibiotics, hydration and anticholinesterase, daily for 3 days. Three days after treatment, his diplopia disappeared and eye position was orthotropic in all directions; this was maintained at the 6 months follow-up.Conclusions: A delayed onset of neurotoxin-induced paralytic strabismus may occur due to viper bite even after antivenom administration. Early anticholinesterase treatment needs to be considered unless contraindicated.