A man has regained his eyesight after the successful transplant of a bioengineered pig cornea in Central China, youth.cn reported on Tuesday.

The man, surnamed Zhang, first experienced pain in his right eye three years ago. In June, he was diagnosed with necrotizing stromal keratitis, a disease that can require a cornea transplant.

About 4 million people have the condition in China, with figure rising about 150,000 a year, yet only 5,000 corneas are donated annually.

It meant Zhang, who was experiencing rapid deterioration in the eyesight in his right eye, faced a long wait for a donor.

Deng Zhihong, executive director of the cornea transplant center at Central South University’s Third Xiangya Hospital in Changsha, Hunan province, warned the patient that, if not properly treated, the disease would result in the removal of his eye.

Due to the urgency of Zhang’s situation, he received a bioengineered cornea transplant, which improved the range of vision loss in his right eye to “moderate”. It is expected to further recover to “mild”.

Bioengineered corneas are substitutes for human donor tissue, and were developed by Chinese scientists using medical technology to ease the shortage of donated corneas.

Deng said that pig corneas are processed using state-of-the-art technology. Patients who receive the transplants are required to use anti-rejection eyedrops for six months after the surgery.

Cheng Si contributed to this story.