The eye consists of two major parts: the wall and the contents of the eye, which are divided into three layers from the outside to the inside: the outer layer is the cornea and sclera, the middle layer is the pigment membrane including the iris, ciliary body and choroid, and the innermost layer is the retina. The contents of the eye are the atrial fluid, the lens and the vitreous humor in descending order. The eye is an important organ of vision, which obtains information from the outside world by “seeing”. Light from the outside world passes through the cornea, atrial fluid, lens and vitreous humor of the eye and can be focused and imaged on the retina, which then transmits visual information to the center through the optic nerve to form vision. In addition, the eye has an aesthetic role.