Need help remembering the title of a film

• The film had to have been released before 2009 as I remember seeing it with my girlfriend at the time. If my memory is correct, we saw it in US theaters around 2007/2008.
• English language.
• It seemed very post-apocolyptic/dystopian, probably still in the 21st century.
• The main character was a woman, either white or tan skin tone.
• A significant detail was a very tall (50-foot, maybe 100-foot) concrete wall keeping something (monsters, zombies, infected people, lower-class people, I can't remember exactly what) out, and there were automated turrets that would shoot anything that moved.
• Either the main character or one of her supporting characters (rebel group, survivors, not sure) had a bionic eye that she/he throws somewhere for reconnaissance.

This has been bothering me for years; if you all can offer any suggestions on what this movie might've been, I'd greatly appreciate it.

EDIT: It was called Doomsday!