China accounts for a fifth of the world's blind people: about 8m of its 1.4bn population.

Corneal disease is responsible for roughly half of these cases, and for many people the only hope is a transplant.

Owing to a lack of human corneas, last year the Chinese government gave the go-ahead for experimental use of pig corneas last year.

About 200 operations have now been carried out.

Wu Pinggui talks to the BBC after having an operation to transplant a pig's cornea into his eye.

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