Upon viewing an object, the image created on the retina is

The human eye acts as a convex lens system. When an object is viewed, the light rays from the object pass through the cornea and the eye lens, converging to form an image on the retina.

Since the image is formed on a screen (the retina), it must be a real image. For a convex lens, a real image formed from an object placed beyond the focal point is always inverted.

Therefore, the image formed on the retina is real and inverted.