Why wont our eyes don't adapt completely to a repeated visual stimulus?

Our eyes do not fully adapt to a repeated visual stimulus due to a phenomenon known as sensory adaptation, which occurs in the nervous system. While the photoreceptors in the retina can become less responsive to constant stimuli, the brain continues to process and interpret these signals, leading to the perception of changes or fluctuations in the stimulus. This mechanism allows us to remain aware of our environment and detect new or important changes, ensuring we do not overlook significant visual information. Thus, while some adaptation occurs, it is not complete to maintain situational awareness.