People who have lost an eye to illness sometimes report strange visual sensations and phantom images. Amputees have been sometimes known to feel sensations where an arm or leg used to be, a phenomenon known as 'phantom limb', but there exists another far more peculiar affliction that leaves patients with only one eye seeing visions in the eye that's no longer there.

Scientists at the University of Liverpool recently conducted the largest known study of Phantom Eye Syndrome (PES) in which they surveyed 239 patients who had lost one of their eyes to cancer.

The results suggested that a total of 60% of those queried had experienced symptoms ranging from pain and unexplained visual sensations to actual hallucinations observed by the missing eye.

These visions sometimes even included images of people standing in the patient's field of view.

"We can now tell whether certain kinds of patients are more likely to have phantom symptoms," said psychologist Laura Hope-Stone. "PES is more common in younger patients, and having pain in the non-existent eye is more likely in patients who are anxious and depressed."

The exact cause of these peculiar symptoms however continues to remain a mystery.