A rare surgery that involved implanting a man’s tooth into his own eye successfully restored vision that had been lost two decades earlier.

When Brent Chapman was 13, he experienced a horrific reaction after taking ibuprofen during a Christmas basketball game. The episode left Chapman burned all over his body and in a coma for 27 days. Chapman also lost his left eye to an infection and lost most of the vision in his right eye.

“For the last 20 years, I’ve been having close to 50 surgeries trying to save this eye, most of them cornea transplants,” Chapman said, per CNN.

“We would put a new cornea in. It would last sometimes just a few months or even up to years, but it would just kind of never heal.”

While Chapma’s body recovered, vision never fully returned. That is, until Dr. Greg Moloney, clinical associate professor of corneal surgery at the University of British Columbia, restored his sight using a rare and unusual procedure.

“I’m very happy and am just taking in the world again, appreciating the little things. It’s been kind of surreal and kind of a euphoric feeling to it,” Chapman said.

Known as a tooth-in-eye or osteo-odonto-keratoprosthesis, the procedure involves removing a person’s tooth, sewing a piece of it into the cheek, and placing the tooth’s structure into the eye. The tooth holds a plastic optical cylinder and eventually grows soft tissue around it.

Later, a hole is made in the front of the patient’s eye, and the tooth-lens complex is integrated with living tissue, eventually replacing the damaged cornea’s function. Tissue from the patient’s mouth is then used to cover the tooth part of the device.

Chapman’s terrifying health episode was caused by Stevens-Johnson syndrome. The rare and potentially fatal condition results in severe inflammation of the skin and mucous membranes, usually a reaction to medication. In certain instances, the immune system can attack the limbal stem cells that are necessary for maintaining a clear cornea. Without them, corneal tissue is scarred and keratinized, almost as if skin is growing over the cornea and preventing light from reaching the retina.