Why are images in the eye formed upside down?

Images in the eye are formed upside down because of the way light is refracted as it passes through the curved lens of the eye. When light rays enter the eye, they bend (or refract) to focus on the retina at the back of the eye, which is a flat surface. This bending causes the brain to interpret the incoming light as being inverted. However, the brain automatically corrects this inversion, allowing us to perceive the world right-side up.