To report an atypical case of ocular toxoplasmosis presenting as isolated unilateral papillitis.

A 53-year-old female presented with visual difficulty in her right eye that had begun 1 week previously. Best corrected visual acuity was 0.8 in the right eye and 1.0 in the left eye. On fundoscopic examination, optic disc swelling and focal edema with hard exudates in the nasal parapapillary retina were found in her right eye. Fluorescein angiography revealed marked leakage of dye from the swollen optic disc. There was no evidence of vasculitis and chorioretinitis. Pupillary light reflex and color vision were normal. Visual field (VF) showed generalized reduction in the right eye, and was normal in the left eye. Optical coherence tomography (OCT) revealed right optic disc swelling. Serology was positive for toxoplasma IgM and IgG. The patient was treated with oral steroids and antitoxoplasma antibiotics. Two months later, visual acuity was 1.0 in the right eye. There was no disc swelling on fundoscopy or OCT and VF was normal.

Ocular toxoplasmosis can present atypically as isolated papillitis without chorioretinitis and mimic idiopathic optic neuritis. A thorough serologic examination for toxoplasmosis along with proper treatment should be performed.