(NBC News) — Twenty people with diseased or damaged corneas had significant improvements in their vision after they received implants engineered out of protein from pigskin.

The patients, in Iran and India, all suffered from keratoconus, a condition in which the protective outer layer of the eye progressively thins and bulges outward. Fourteen of the patients were blind before they received the implant, but two years after the procedure, they had regained some or all of their vision. Three had perfect vision after the surgery. 

The research team behind the technology published its findings Thursday in the journal Nature Biotechnology.

“We were surprised with the degree of vision improvement,” said Neil Lagali, a professor of experimental ophthalmology at Linköping University in Sweden who co-authored the study.

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