The Ebola virus has been detected for the first time in an eye of a patient months after it vanished from his blood, researchers in the US said.
The announcement on Thursday said the virus reappeared in Dr Ian Crozier who was diagnosed with Ebola in September 2014 while working in Sierra Leone with the World Health Organization.
He was sent back to the US to Emory University Hospital's special Ebola unit in Atlanta, Georgia.
Crozier left the hospital in October when Ebola was no longer detected in his blood, the New England Journal of Medicine reported on Thursday.
But two months later he developed an inflammation and very high blood pressure in his left eye. It caused swelling and serious vision problems.
He returned to the same hospital where he had been treated, and an ophthalmologist, Dr Steven Yeh, removed some of the fluid and tested it for Ebola. It did in fact contain the virus, but it was not present in his tears or the tissue around his eye.
Doctors believed he did not pose a risk of infecting other people, but Yeh said the case shows that survivors of the deadly virus should be monitored for possible eye infection.
It is not known how long the condition can last.
The infection caused an inflammation of the inside of his eye.
Besides the problems with his vision, his iris changed colour, going from blue to green 10 days after the symptoms were first detected.
After undergoing treatment with a variety of medicines, Crozier began to recover his vision but it is still not complete. And his eye colour returned to normal.
Cases of eye inflammation had been reported among survivors of Ebola in previous, limited epidemics and among people with a virus known as Marburg, which is similar to Ebola. But such cases are rare, the medical journal said.
The worst ever outbreak of Ebola began in southern Guinea in December 2013 before spreading to Liberia and Sierra Leone.
The death toll now exceeds 11,000, the World Health Organisation reported this week.