Patients who lose an eye may feel like they still 'see' light, color

Some patients who lose an eye to cancer surgery feel as if they can still see out of the missing eye, a phenomenon known as "phantom eye syndrome," according to a study published today.

The phenomenon is similar to phantom limb pain, in which people who lose an arm or leg continue to feel pain in the missing limb, said study co-author Bertil Damato, director of ocular oncology at the University of California-San Francisco.

About 28% of patients experienced "vision" in the missing eye — such as complex images of people — and half reported "visual sensations," such as colors or shapes, according to the study, published in Ophthalmology. One-quarter of patients had pain in the missing eye.

All 179 patients in the study had undergone surgery for a rare form of melanoma, uveal melanoma, that develops in the eye.

Some patients said they could see things like fireworks or kaleidoscopes with the missing eye. An 82-year-old man said he saw a figure walking at his side. A 77-year-old woman reported that she could see people when it's dark. A 70-year-old woman said she "awoke to find a person ... standing next to the bed."

Patients who had pain in the eye before surgery were more likely than others to report pain after the eye was removed, Damato said.

Doctors can't explain why people who lose an eye might still feel as if they can see, Mary Beth Aronow, an assistant professor of ophthalmology at the Johns Hopkins Wilmer Eye Institute, said.

During cancer surgery, doctors have to sever the optic nerve, which leads from the retina to the brain. Aronow compares the optic nerve to a bundle of wires made up of 1.7 million axons — the long, threadlike parts of nerve cells.

"When the optic nerve is severed, those connections are still firing," Aronow, who wasn't involved in the study, said.

These remaining parts of the nerve may be responsible for the visual sensations, she said.

Patients reacted differently to the images. About 20% found them disturbing, while 20% described the visual sensations as pleasant, researchers found. Patients who had pain in the missing eye were much more likely than others to experience depression or anxiety, the study said.

Doctors treating patients with uveal melanoma should warn them that these sensations could occur, and reassure people that they aren't hallucinating, Damato said.

Some patients said that darkness or fatigue caused their symptoms to flare up. Some found that they could make the visual sensations go away by resting, rubbing their eyes, blinking or distracting themselves, he said.

Between 1,500 and 2,000 Americans a year develop uveal melanoma, Damato said. The cancers develop almost exclusively in Caucasians, particularly in those with blue or gray eyes. There's no evidence that the cancers are caused by direct sun exposure to the eye. Doctors debate whether wearing sunglasses offer any protection from uveal melanoma, although they can protect the skin around the eye. Sunglasses also reduce the risk of cataracts, Damato said.