Ocular involvement in West Nile virus infection: a multimodal imaging study

To characterise the chorioretinal (CR) manifestations of West Nile virus (WNV) infection using multimodal imaging (MMI).

Retrospective cohort study including 37 patients with confirmed WNV infection hospitalised at a single centre (July-September 2024). All underwent comprehensive ophthalmological evaluations, including visual acuity, slit-lamp biomicroscopy, fundoscopy, and multimodal imaging: fundus photography, spectral-domain optical coherence tomography (SD-OCT), fundus autofluorescence (FAF), fluorescein angiography, and indocyanine green angiography when clinically indicated. Clinical characteristics and imaging findings were compared between patients with and without ocular involvement.

Ocular involvement was identified in 17 patients (46%); CR lesions were the predominant finding identified in 28 eyes of 15 patients. Those with ocular involvement exhibited significantly higher rates of neuroinvasive disease (94% vs. 60%, p = 0.017) and mechanical ventilation (35% vs. 5%, p = 0.024). Lesions displayed various distributions, including curvilinear patterns along the retinal nerve fibre layer (32%), scattered multifocal patterns (21%), or mixed (46%). MMI revealed a spectrum of CR lesions, from clinically invisible lesions detected only on FAF to clinically apparent lesions. Retinal pigment epithelium (RPE) involvement correlated with outcomes. Lesions limited to the outer retina resolved within 1-2 months, while RPE disruption led to scarring or atrophy. In six eyes, OCT demonstrated more extensive involvement extending to the inner retinal layers.

WNV-related ocular involvement is strongly associated with neuroinvasive disease. MMI, particularly FAF and OCT, identifies clinically invisible retinal lesions, extending the known spectrum of disease. Early retinal imaging in neuroinvasive WNV cases is essential for precise diagnosis and management.