First, let’s look at the general composition of the eye. If we compare the eye to a camera, then the eye is a very sophisticated camera, in which the eyelid is opened and closed as usual under the lens cover, hiding the cornea and the lens two aspheric lens. The cornea is at the forefront of the eye, both to protect the eye and to play the role of a fixed-focus lens; the lens is inside the eye, hiding behind the pupil (equivalent to an iris) that can stretch freely, playing the role of a zoom lens. Unlike a camera, the two lenses of the eye have to work together and focus collaboratively in order to take in everything in sight. Speaking of the fundus, let’s understand the vast space between the lens and the fundus. This space is filled by a collagen fiber hydrate called vitreous humor, which is semi-solid and has a structure somewhat like a transparent jelly. The role of this vitreous body in the eye is, simply understood, to fill the eye, cushion the shock, and support the retina. Now let’s go to the very back of the eye and take a peek. The last side is the fundus of the eye, there is a fine structure called the retina, the normal retina is like the best imaging quality camera negative, eyelids blink between the wonderful collection of the retina. Behind the eye trails a thin optic nerve, which is so important that it acts as a data line for a digital camera, transmitting the information collected by the retina to the workstation in the cerebral cortex. The precise window of the mind needs to be well protected.