When asked what she wanted to do now that she had regained her vision, she replied: "Before, my husband took care of me, but now I am able to see. I will take care of him."

"Her answer was simple, and her eyes were as pure as a child's," says Wang, adding that it consolidated his determination to carry on the program of providing eye care for people in Tibet.

In 2012, Wang led a medical team to Tibet for the third time. And they received a 3-year-old girl, Penchung, who was born with cataract.

"Congenital cataract is more complicated than age-related cataract. Congenital cataract surgery needs an enclosed environment," says Wang.