Clinicopathologic Reports, Case Reports, and Small Case Series
December 01, 2005

Extensive Chorioretinitis and Severe Vision Loss Associated With West Nile Virus Meningoencephalitis

Author Affiliations



Copyright 2005 American Medical Association. All Rights Reserved. Applicable FARS/DFARS Restrictions Apply to Government Use.2005

Arch Ophthalmol. 2005;123(12):1754-1756. doi:10.1001/archopht.123.12.1754

West Nile virus is an arthropod-borne flavivirus that was first documented to affect humans in the United States in August 1999.1 Since that time, the infection has spread across North America, with 9862 human cases reported in 2003 alone.2 The majority of patients with these infections are asymptomatic, but approximately 20% develop an acute febrile illness accompanied by malaise, headache, myalgia, arthralgia, skin rash, and gastrointestinal symptoms lasting less than 1 week. Advanced age and the presence of diabetes mellitus have been identified as risk factors for severe neuroinvasive disease, including meningitis and encephalitis.1

The common intraocular manifestations of West Nile virus infection have been described in several recent articles.38 Bilateral, multifocal chorioretinitis with circular “target-like” lesions scattered in the midperiphery and often arranged in a radial linear pattern has been a consistent feature. Other intraocular findings include mild iridocyclitis, vitritis, occlusive retinal vasculitis, and optic disc edema. Although patients may suffer a significant decline in visual function initially, visual acuity tends to recover to near-baseline levels, and chorioretinal involvement is typically not extensive. We report a case of severe, widespread bilateral chorioretinitis and profound permanent vision loss in association with West Nile virus infection.

Report of a Case

A 68-year-old female Illinois resident had a fever (38.9°C-39.5°C), clear nasal discharge, headache, myalgia, fatigue, and dry cough for several days. Medical history was significant for non–insulin-dependent diabetes mellitus, hypertension, congestive heart failure, and coronary artery disease. Chest radiography revealed left lower lobe atelectasis, prompting admission to the hospital for intravenous antibiotics. Blood and urine culture results were negative. On hospital day 5, the patient’s mental status deteriorated, and she required intubation. Computed tomography and magnetic resonance imaging of the head showed normal results. Cerebrospinal fluid examination revealed West Nile virus IgM antibodies in addition to pleocytosis and elevated protein and glucose levels. Study results for St Louis encephalitis and other infectious causes were negative.

After 1 week of supportive therapy, the patient was extubated. She was oriented to person and place only. Bedside ocular examination revealed bilateral light perception visual acuity. The pupils were equal and reactive to light without afferent defects. Penlight and ocular motility examination results were normal. Fundus examination revealed discrete, multifocal, atrophic chorioretinal lesions of variable sizes scattered randomly throughout the macula and midperiphery of each eye. The vitreous was grossly clear, and the optic discs were pink and flat. Several small intraretinal hemorrhages were observed in each eye.

The patient’s health improved over the subsequent 5 months, but the visual function remained unchanged. Magnetic resonance imaging revealed T2 high-signal abnormalities in the deep frontal lobe white matter, which is consistent with prior encephalitis. Fundus examination and fluorescein angiography revealed extensive atrophic chorioretinal lesions throughout the macula and midperiphery of each eye, with mild segmental vascular leakage in the left eye (Figure). Ganzfeld electroretinography revealed a 50% reduction in rod responses, with cone responses of normal amplitude. Oscillatory potentials were reduced, and flicker responses were of marginal amplitude with a delayed time to peak.

Image not available

Composite fundus photograph of right eye (A) and left eye (B), 5 months following disease onset. Note the extensive atrophic chorioretinal lesions throughout the macula and midperiphery of each eye. C, Composite fluorescein angiogram of the left eye highlights atrophic lesions and shows mild leakage from vessels in the superior macular area. Widely scattered microaneurysms are likely related to mild nonproliferative diabetic retinopathy.

Eight months after initially developing these symptoms, the patient’s mental status had returned to baseline. The visual acuity remained hand motions in the right eye and light perception in the left eye. The fundus appearance was unchanged.


The chorioretinal lesions seen in our patient are similar to, but much more extensive than, those described in previous articles.37 We presume that the severity of both the neurological and the chorioretinal involvement in our patient is associated with immune compromise related to senescence and diabetes mellitus. In contrast to our patient, previously described patients with ocular involvement by West Nile virus have suffered less initial visual loss and have usually enjoyed visual improvement during disease resolution.38 The severity of the visual loss in the present case is clearly related in part to the degree of chorioretinal damage seen clinically and angiographically. However, the mild to moderate changes in electroretinography responses do not support visual loss to the light-perception level. In the context of such profound visual loss, the electroretinography findings, reactive pupils, and healthy-appearing optic discs suggest that retrogeniculate damage is likely a contributing morbidity. Because routine magnetic resonance image scanning has failed to show structural damage in this area, functional magnetic resonance imaging studies are planned.

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Article Information

Correspondence: Dr Johnson, Department of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, 1000 Wall St, Ann Arbor, MI 48105-0714 (

Financial Disclosure: None.

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