[Buddha-l] blind Huineng

[Mitchell Ginsberg]

Hello all, I have found a reference to Huineng (Hui Neng) that described him as blind. 
I do not recall having heard of that before. 
Would anyone know if there are grounds one way or the other for thinking that Huineng (the sixth Chinese Ch'an Patriarch, I mean) was literally blind, unable to have any visual perception? 
Where can there more on this be found? 
Thank you. 
Mitchell