Abstract
A 59-year-old man who experienced severe visual loss in the right eye for two days following a febrile illness (high fever lasting for 15 days) presented to our center for a second opinion. On examination, his Snellen best corrected visual acuity (BCVA) was 1/10 in the right eye and 9/10 in the left eye. On fundoscopy, we observed a few track-like, cream-colored linear lesions in the superior fundus of the left eye and a small whitish foveal discoloration together with a temporally pallid disc in the right eye. On autofluorescence imaging, there were some scattered hyperautofluorescent patchy areas bilaterally and, most notably, several hyperautofluorescent track-like lines in the left eye. A complete systemic evaluation was carried out and a blood sample was sent via the Provincial Health Directorate for West Nile virus (WNV) polymerase chain reaction and immunoglobulin (Ig) M and G testing. IgM and IgG antibodies were detected by immunofluorescence assay. The diagnosis was bilateral WNV chorioretinopathy. Magnetic resonance imaging of the brain ruled out any central nervous system involvement. A right intravitreal ranibizumab injection was administered for the intraretinal edema. A month later, Snellen BCVA was 2/10 in the right eye 10/10 in the left. Hyperautofluorescent lesions were no longer detectable in either eye but the right optic disc still appeared pallid. Clinicians should suspect WNV horioretinitis in cases presenting with characteristic fundus lesions and a history of febrile illness.