By lore, races such as dark elves and orcs do see better in the dark, which translates into a line of sight bonus inside dungeons (or is supposed to, not sure if it works) and a penalty under daylight, respectively. The Darkness you find in dungeons or create with spells is a magical sort of darkness. Bright light will penetrate it, but eyes alone won't work. At least not the eyes of one of the player races.