Why would Ben want to donate seven pounds of flesh?
Is the gift Ben gave to Ezra possible?
Not the entire eye, which would require attaching the transplanted eye to the existing optic nerve, which is medically impossible (so far). However, blind is a generic term for not being able to see. There are various conditions that can make a person blind, and some of these ARE curable through transplants, e.g., corneas.
So what's the big twist in this movie?
Before Seven Pounds was released in December 2008, the studio refused to reveal the details of the movie in the early trailers. Now that the movie is out, it's become common knowledge that Will Smith is playing a man who arranges to donate parts of his body ("seven pounds" of his flesh) to individuals in need of transplants. What still may not be widely known are two other twists, one that should be obvious and one that isn't. (1) Obviously, in order to donate parts of his body, Ben must kill himself, and (2) Will Smith's character Ben is not Ben at all. His name is Tim, and Ben is his brother.