Since the visual images are projected in an inverted manner on the retina why don't we see things upside down?
As the crystalline lens is a convex spherical lens it forms inverted images on the retina (each converging lens forms inverted images). The inverted information follows by the optical nerves until the occipital cerebral cortex that having the visual area of the brain. In the brain the interpretation of the image takes place and the inverted information is reverted.