Isolated Optic Neuritis Revealing Lyme Disease in an Adolescent: A Case Report and Literature Review.

Lyme disease, caused by Borrelia burgdorferi sensu lato, can occasionally involve the nervous system and lead to a variety of neurological manifestations. Ocular complications are uncommon, and optic neuritis (ON) represents one of the rarest presentations. We describe the case of a 17-year-old girl from Morocco who developed progressive visual loss and eye pain on the right side. Ophthalmologic evaluation revealed unilateral optic disc swelling and macular edema, and magnetic resonance imaging confirmed right optic nerve inflammation. Cerebrospinal fluid analysis demonstrated lymphocytic pleocytosis and elevated protein, while serological and intrathecal testing identified B. burgdorferi infection. The patient was treated with intravenous ceftriaxone for 21 days without corticosteroids and experienced near-complete recovery of vision. This case highlights the importance of considering Lyme disease in the differential diagnosis of ON, even in regions where it is rarely reported. Early recognition and antibiotic therapy can lead to excellent visual outcomes and prevent misdiagnosis as demyelinating disease.