The dimension of the smallest object seen at a specific distance is called visual acuity. It is very low in a small baby who lives in a world of vague shapes but he progresses rapidly and at about 6 months old has one fifth of an adult's visual acuity. This is done by both eyes, the images in each eye being being seen under different angles, which gives the brain a sense of depth perception. The brain merges both images to make a single image in normal binocular vision. If both eyes cannot look at the same point, there is strabism or squinting.
Binocular vision affords a wide field of vision.
The performance is far more limited with only one eye. If you close one eye, the vision is less good than with both eyes. The normal field of view is of 220 to 240 degrees in a horizontal direction, but the best visual acuity is right in the centre of the field of view. The child sees color by means of three different cells on the retina, one responding to blue, the other to green and the last to red. At present, there is no treatment available for color deficiency or color blindness.