Eli: In all these years I've been carrying it and reading it every day, I got so caught up in keeping it safe that I forgot to live by what I learned from it.
Eli: People had more than they needed. We had no idea what was precious and what wasn't. We threw away things people kill each other for now.
Martha: George, what's wrong?
George: A whole company of armed degenerates, that's what's wrong! And they led them straight to us!
Martha: I just set out the good china.
George: Fuck the china!
Eli: Stay on the path. It's not your concern. Stay on the path. It's not your concern.
Answer: A large study was done after the atomic blasts in Japan in WW2 after the surrender on the effects to victims' eyesight. Over 70% of the people that indirectly looked at the light were not completely blind. They suffered from cataracts, and out of those studied over 50% could see during the day - mostly shades of black and shadows / silhouettes of people and objects. Those that survived became very keen to see movement as long as they were in bright light, also heightened since of smell and feeling vibrations. This would explain why Eli never traveled at night and was not totally blinded by a nuclear flash, if he was completely blind - night would give him a much larger advantage. You notice he always travels when the sun comes up so he can see silhouettes of people and objects moving. Also when Solara interred his room at Carnegie's hall she said "it's bright in here" Eli had all the lights on so he could see anyone entering the room / cell. Also he wears sunglasses because obviously he does not want his cataracts to get worse. If you watch the movie again there are many tells to support that he is only partially blind and had mild to moderate cataracts. You can also see his eyes on the boat to Alcatraz, showing his cataracts.
He was born blind, at the start he smells the hijackers and moves into the dark to level the playing field.
How would he know where the dark is?
He was not born blind. He was blinded during armageddon, but after finding the Bible was given his sight back in order to complete the task given to him by God. Once his task was completed he once again lost his sight.
Nope! He was given his sight back by God in order to complete the task he was given, only to lose it once again after it was completed.