Atypical Form of Unilateral Optic Neuropathy Caused by Ocular Toxocariasis

Purpose: To report an atypical form of ocular toxocariasis presenting as unilateral optic neuropathy.Case summary: A 75-year-old man was referred to our clinic owing to the recently developed visual difficulty in his right eye. The visual acuity of the right eye was 0.4, a relative afferent pupillary defect was positive in the right eye. On slit lamp biomicroscopy, anterior chamber inflammation and vitreous cells and haze were detected in the right eye. On fundus examination, optic disc swelling and focal retinitis around the optic disc were found in the right eye. Fluorescein angiography revealed focal retinitis along with leakage near the optic disc in the right eye. Serology was positive for Toxocara IgG. Under the suspicion of an atypical form of ocular toxocariasis, the patient was treated with local and oral steroids and albendazole. Subsequently, optic disc swelling and vitreous inflammation improved, but the final visual acuity was 0.125 with pale optic disc and central visual field defects in the right eye.Conclusions: In patients suspected of optic neuritis, when the anterior chamber and vitreous inflammation and uveitis are accompanied, ocular toxocariasis can present atypically and requires attention because may have a bad prognosis owing to irreversible optic nerve damage.