He is blind, although it is not always obvious. This was particularly the case for me since I saw this movie on a plane, which had been edited (the movie, not the plane).
Some of the subtle clues to demonstrate he is blind:
- When he flicks the lighter open and flicks it, he moves his hand over the flame to prove to him it works because he's blind.
- He kept clicking the iPod even though it said battery low. If he could see, he'd realize the battery was low. Only after clicking like crazy did he realize it was low.
- He kicked the bottom stair before walking up the steps to the old folks house.
- He didn't see the no trespassing sign because he was blind.
- At the beginning of the movie, he shoots a hairless cat only when he hears it move.
- It is only after Eli is fired upon from the guy on the roof that Eli takes cover and fires back. And each time someone fires on him, Eli turns in that direction and returns fire. Eli accidentally shoots Carnegie in trying to shoot the guy running in Carnegie’s direction.
- When Solara first comes to seduce Eli she is obviously dressed for solicitation and she says "don't worry you don't have to pay." Eli replies "pay for what," since he can't see all the visual clues that Solara is giving him.
- Just before he cooks the cat, Eli searches the house he's in. While he does so, he touches the contents of a shelf in order to glean what its contents are.
