Our eyes see an upside-down world—but our brain flips it for us. When light reflects off an object, like a tree, photons enter the eye through the cornea and lens, which bend (or refract) the light to focus it onto the retina. Because the lens is convex, it naturally inverts the image, projecting a real, upside-down version of the scene onto the retina's photoreceptor layer. From there, the optic nerve transmits this inverted information as electrical signals to the brain’s visual processing center—the primary visual cortex in the occipital lobe. It’s here that the brain performs an astonishing feat: it automatically reorients the image, correcting it so that we perceive the world right-side up. This seamless process of ocular refraction, neural transmission, and cortical interpretation happens continuously and instantly, forming the foundation of how humans visually interact with reality.
