Teenager presents with new onset diplopia, ptosis

A 17-year-old white boy with myopia presented urgently to the pediatric ophthalmology department for new onset diplopia and ptosis of the left upper lid. He had developed binocular diplopia for 4 days before presentation, as well as left upper lid ptosis, which worsened in the last 2 days. He denied any other changes in vision but did complain of pain in the right eye with eye movement.Review of systems was positive for a mild headache, a 1-month history of upper respiratory infection symptoms and mild fatigue. He had mild paresthesias on the right side of his face. He also reported multiple erythematous ring-like lesions on his body, treated as tinea corporis with a topical antifungal. Medical history was significant for attention deficit disorder treated with Concerta (methylphenidate, Janssen Pharmaceuticals). Family history was unremarkable. He denied tobacco or alcohol use and had no known drug allergies. He lives in a heavily wooded area and has pulled ticks off his skin in the past.