How this pig helped a man to see again
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.
Read more: How China is super-sizing science
- From the section Magazine