What is the Purpose of the Retinal Image?

In some ways, the eye works like a camera obscura, as Kepler described in 1604. The lens of the eye forms an upside-down and backward, two-dimensional image of whatever you are looking at, on the concave inner back wall of the eye. A doctor can see your retinal image when she looks into your eye. But you can’t see your own retinal image, so what is the point of having it? And even if the retinal images were copied to the brain (which they are not), you still couldn’t see them. What are they for?