A Case of Branch Retinal Artery Occlusion With Concomitant Intraocular and Extraocular Toxoplasmosis Lesions in a Japanese Man

<b>Purpose:</b> The purpose of the study is to report a case of ocular toxoplasmosis with branch retinal artery occlusion (BRAO). <b>Case:</b> The patient was a 36-year-old man from Okinawa, Japan, who was generally healthy and had no medical history. He was referred to our hospital with a complaint of sudden loss of vision in the left eye. Best corrected visual acuity was 0.1 in the left eye at the initial examination, and intraocular pressure was 21 mmHg. Anterior segment slit-lamp examination showed a few cells of the anterior segment and anterior vitreous. Fundus examination of the left eye showed retinal vasculitis of the middle and large retinal vessels with occlusion of retinal arterioles in the macular area and edema in all layers of the retina, with dense posterior vitreous cells and flare. Magnetic resonance imaging (MRI) showed a mass shadow at the posterior part of the left eyeball near the macula in the orbit. On laboratory examination, toxoplasma serum IgM and IgG were positive. Based on these results, he was diagnosed with BRAO with concomitant intraocular and extraocular toxoplasmosis. He was then treated with clindamycin, sulfamethoxazole-trimethoprim, and steroids. The inflammation disappeared quickly, and visual acuity improved to 0.6. The inflammation had not flared up even 3 months after the initial visit with decreasing serum toxoplasma serum IgG levels, and the posterior eyeball shadow on the MRI disappeared. <b>Conclusion:</b> A case of BRAO with uveitis with concomitant intraocular and extraocular toxoplasmosis lesions was presented. In cases of unilateral retinal vasculitis with orbital lesions, concomitant intraocular and extraocular toxoplasmosis should also be considered.