All birds have a dominant sense of vision. In most of them, the eyes are placed so far to the side of the head that they have monocular vision, that is each eye can scan a separate area. This is an essential feature shared by all hunting creatures who depend on their vision to beware of possible danger.
Birds of prey and owls have eyes set more to the front of the head, giving a more binocular vision to judge distances. Birds also have a third eyelid, which moves sideways across the cornea and keeps it moist without interrupting their vision.
Below Birds Vision info from Wikipedia (Read More):-
Vision is the most important sense for birds, since good eyesight is essential for safe flight, and this group has a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings".[1] The avian eye resembles that of a reptile, but has a better-positioned lens, a feature shared with mammals. Birds have the largest eyes relative to their size within the animal kingdom, and movement is consequently limited within the eye's bony socket.[1] In addition to the two eyelids usually found in vertebrates, it is protected by a third transparent movable membrane. The eye's internal anatomy is similar to that of other vertebrates, but has a structure, the pecten oculi, unique to birds.
http://en.wikipedia.org/wiki/Bird_vision
