The finding was reported in the March issue of the journal Clinical Infectious Diseases. OSU ophthalmologist Dr. William Anninger, lead author of the report, included in the article an alert to physicians diagnosing and treating patients with the infection that permanent eye damage can result.
“It’s a very rare consequence of West Nile infection, but there have been approximately 10 clear reports nationally that the virus had an effect on the eyes,” Anninger said. “This is the way medicine works – we start with case reports, and as more cases accrue, researchers can look for patterns and create protocols to make sure patients are getting appropriate care.”
In the case reported by Anninger, the patient’s vision diminished from 20/25 to 20/80 in the right eye and 20/40 in her left – enough to reduce her ability to read three lines on the standard eye examination chart. Within a year after recovering from the acute symptoms of the infection, she regained central vision in her left eye, but reports vision of 20/60 in her right eye and permanent loss to her peripheral vision.
Her symptoms at the time she was hospitalized with the infection included headache and fever as well as clouding in both eyes that she described as a “black fog.”
Anninger and colleagues suspect such eye damage occurs in patients whose West Nile virus infection progresses to meningoencephalitis, or infection of the brain.
“The optic nerve is an extension of the brain, and when patients get meningitis or encephalitis, that’s how the infection in the brain reaches the eye or can affect vision,” Anninger said. He said symptoms of such an infection in the eye could include soreness and redness, and an exam might reveal a prevalence of white blood cells within the eye.
Anninger said there currently is no treatment available to repair a damaged optic nerve, and more cases must be observed before patterns could be detected to predict which patients with West Nile virus infection are most likely to experience symptoms in the eye.
According to the Centers for Disease Control, the best currently available West Nile virus prevention is protecting against mosquito bites; infected mosquitoes’ bites can transmit the illness to humans. An estimated one in 150 people infected with West Nile Virus will develop the more severe symptoms associated with the disease, which to date has been reported in 45 states.
“The infection itself is still rare,” Anninger said. “I would just suggest that health care professionals keep this in the back of their mind, that someone with a more advanced West Nile virus infection could experience eye problems. It might be worthwhile to refer those patients to an ophthalmologist.”
Anninger co-authored the report with Dr. Martin Lubow, associate professor emeritus of ophthalmology at OSU Medical Center.