He donates to charities that research eye diseases and help to restore the eyesight of blind people.
On multiple occasions, Banksy has donated his art to help raise money for charities that work to restore sight and prevent eye diseases. On his website's FAQ, he responds to the request for money to charity with "What are you? Blind? In which case maybe. I mostly support projects working to restore sight and prevent eye disease. Or 'expanding the market' as you might call it."