Our eyes are like a camera, the camera can leave a beautiful view of the lake and the mountains, and the eyes can see the colorful world. But the eye is much more advanced than any sophisticated camera, and its efficient, sensitive and precise functions are incomparable to any camera, so we can call the eye a super camera. The eye is composed of the transparent cornea, atrial fluid, lens, and vitreous humor from front to back of the refractive system of the eye, which is equivalent to a set of lenses of a camera. The outer shell of the eye is composed of the sclera, uvea and retina from outside to inside. The sclera and uvea play the role of the camera obscura, the retina is like the camera negative, the pupil in the center of the black eye can be as large or small as the camera aperture, and the lens and ciliary body work together to adjust the role as the focal length of the camera lens. Sudden power failure at night, surrounded by darkness! Turn on the flashlight we can not only see the light from the torch, but also see the objects in the area illuminated by the torch light. In shopping malls with clear windows, it is common for someone to be hit by a clear glass door with a bloody head! Therefore, to see objects, we need not only light, but also objects that reflect light, and the reflected light enters our eyes in order for us to see. For example, when reading a book there must be light shining into the book and reflected into the eye for us to see the contents of the book. Light hits an object, and after the reflection of the object, some of the light enters our eyes, refracted by the cornea, atrial fluid, lens, and vitreous humor, focused on the retina and imaged, the retina transmits the signal along the optic nerve to the optic center of the brain, triggering the judgment of vision, so we see the object.