When you rub your eyes too hard, you may see flashing lights and colors due to a phenomenon called pressure phosphenes. Rubbing your eyes generates mechanical pressure, which stimulates the retina—the light-sensitive layer at the back of the eye. This pressure can trigger the activation of retinal cells, causing them to fire and send signals to the brain. The brain interprets these signals as flashes of light and random colors, resulting in the visual sensations experienced when rubbing your eye