After using our eyes for a long time, our eyes will feel tired. At this time, many people will involuntarily close their eyes, rub and relax. But have you ever noticed that when we rub our eyes too much, some strange patterns often appear in front of us. What's going on? Is it possible that we have spied on something? Stress can lead to hallucinations The strange patterns seen when rubbing the eyes can change the shape and move position at will without control. This phenomenon is called optical illusion in medicine. In other words, it is a subjective feeling of light or color when no light enters the eyes. There are many forms of optical illusion, among which the pressure vision illusion caused by pressing the eyeball with the eyes closed is the most common one. In addition, when the head is physically impacted, we will also produce motion light illusion, which is often referred to as "seeing Venus". In this way, optical illusion often appears in our lives. What is the scientific principle behind it? The reason why we can see objects is that when light enters our eyes, it will stimulate retinal cells to send out visual information. The neurons responsible for receiving information will convert the received signal into "electronic pulse", and then the complex processing of the brain can form the image we see. However, because retinal cells cannot distinguish the types of external stimuli, they can also be stimulated by pressure, not just light, to send out visual information. When we rub our eyes, we put some pressure on the cells in the retina to think that light is coming, so we have optical illusion - we can see those strange patterns. Artificial optical illusion may make the blind regain "vision" Rubbing the eyes is not the only way to cause optical illusion. Sometimes, when we suddenly open our eyes, optical illusion will also appear, and strange patterns will appear on the things in front of us; Optical illusion will also appear when we sneeze or cough violently. At this time, although the eyeball is not directly stimulated, it will also be oppressed, resulting in short-term ischemia of retinal vessels and stimulating the cerebral visual cortex to induce luminous illusion. In addition, hallucinations can also occur during migraines. Although scientists are not yet fully sure what causes hallucinations in migraines, it is likely to be caused by abnormal local discharges in the brain. At present, optical illusion has no special significance for people with normal vision, but it may be of great significance for people who are blind. Scientists have found that using electrodes to stimulate the brain's visual center can generate light spots at specific locations in the visual space, allowing subjects to see an understandable image composed of multiple halos, such as different letters. Researchers speculate that artificially creating optical illusions may really bring hope for blind people to regain their "vision". I would like to remind you, especially children, that although optical illusion is a wonderful experience and does no harm to our body, rubbing our eyes for a long time will let the bacteria in our hands enter our eyes or cause eye diseases. (Xinhua News Agency)