ATLANTA — When Dr. Ian Crozier was released from Emory University Hospital in October after a long, brutal fight with Ebola that nearly ended his life, his medical team thought he was cured. But less than two months later, he was back at the hospital with fading sight, intense pain and soaring pressure in his left eye.

Test results were chilling: The inside of Dr. Crozier’s eye was teeming with Ebola.

His doctors were amazed. They had considered the possibility that the virus had invaded his eye, but they had not really expected to find it. Months had passed since Dr. Crozier became ill while working in an Ebola treatment ward in Sierra Leone as a volunteer for the World Health Organization. By the time he left Emory, his blood was Ebola-free. Although the virus may persist in semen for months, other body fluids were thought to be clear of it once a patient recovered. Almost nothing was known about the ability of Ebola to lurk inside the eye.

Despite the infection within his eye, Dr. Crozier’s tears and the surface of his eye were virus-free, so he posed no risk to anyone who had casual contact with him.

More than a year after the epidemic in West Africa was recognized, doctors are still learning about the course of the disease and its lingering effects on survivors. Information about the aftermath of Ebola has been limited because past outbreaks were small: no more than a few hundred cases, often with death rates of 50 percent to 80 percent. But now, with at least 10,000 survivors in Guinea, Liberia and Sierra Leone, patterns are emerging.