having two eyes instead of just one is advantageous in at least six respects : the danger of blindness is decreased , the visual field is enlarged , stereoscopic depth perception is possible on the basis of binocular disparities , the position of the eyes relative to the head can be computed from the images of both eyes , visual obstacles in front of the horopter perceptually shrink , and the signal-to-noise ratio is increased .
C0018670
head
C0015392
eyes