A report released this week by the U.S. journal New England Journal of Medicine (NEJM) described a case in which Ebola was present in the eye's aqueous humor -- the clear fluid in the front of the eye, between the lens and the cornea -- 10 weeks after the virus was cleared from the patient's blood.

　　Despite the presence of Ebola in the eye, the researcher were quick to note that samples from the patient's tears and conjunctiva, the surface of the eye and eyelids, tested negative for the virus, indicating that casual contact with Ebola survivors carries no risk.

　　The patient, identified by U.S. media as 43-year-old Ian Crozier, was diagnosed with Ebola in September, while working in an Ebola treatment unit in Sierra Leone as a doctor for the World Health Organization.

　　Ebola may persist in survivors eyeballs for months: <a href=http://www.hxen.com target=_blank class=infotextkey>study</a>

　　He was then transported to the United States and treated at Emory University Hospital's Serious Communicable Disease Unit for 40 days, including 12 days of mechanical ventilation and 24 days of renal replacement therapy.

　　After his blood and urine tested negative for the virus, Crozier was discharged home. A semen sample obtained on the day of discharge, however, tested positive, so he was advised to abstain from sex or to use condoms for at least three months, according to the NEJM report.

　　Shortly after discharge, Crozier found he had new symptoms, including low back pain. Two months later, he returned to the same hospital with an inflammation called uveitis and increased pressure in his left eye. The resulting swelling led to reduced vision, and surprisingly, the eye's color changed from blue to green.

　　So, his doctors stuck a needle in his eye and obtained an aqueous humor sample, which tested positive for the Ebola virus.

　　"It felt almost personal that the virus could be in my eye without me knowing it," Crozier told the New York Times.

　　Data on eye complications among survivors in the current outbreak are limited. Although 40 percent of participants in a recent survey of 85 Ebola survivors in Sierra Leone reported having "eye problems," the incidence of uveitis in this group was unknown, the NEJM report said.

　　Several studies of prior outbreaks, however, showed that Ebola infections often manifest in the eyes and can impact vision and cause blindness long after a systemic infection has cleared.

　　One study on survivors of the 1995 Ebola outbreak in the Democratic Republic of Congo found that three of 20 survivors later developed uveitis, which was marked by eye pain, light sensitivity, reduced vision and excessive tearing.

　　Lead author Steven Yeh, an ophthalmologist at the Emory Eye Center, believed that surveillance for the development of eye disease in the post-Ebola period is needed.

　　"The presence of viable Ebola virus in the eye could mean that other Ebola survivors may also be at risk for the development of uveitis," he said in a statement.

　　"The thousands of Ebola survivors in West Africa and health care workers in their home countries will need to be monitored for eye disease in the post-Ebola period," Yeh said.

　　The findings also pointed to a need for infection control precautions when Ebola survivors underwent invasive procedures involving the eyes, they said.

　　As for Crozier, he has experienced visual recovery following therapy for the uveitis. His eye color also returned to normal, but why his eye changed color is still a mystery.