The eyeball is composed of the iris and sclera, with the pupil in the center of the iris. The cornea is a transparent membrane connected to the sclera. Behind the iris is the lens, which is connected to slender tendons, and behind it is the vitreous body.
The wall of the eyeball
The wall of eyeball can be divided into three membranes: outer, middle, and inner. The outer membrane is the cornea and sclera. The media is the iris, ciliary body, and choroid. The ciliary body is connected to the root of the iris and contains the ciliary muscle. The choroid is a structure rich in blood vessels and pigments that is close to the retina. The retina is the inner membrane of eyeball wall and contains a large number of photoreceptors and nerve connection cells.
The outside of the eyeball’s sclera
The outside of the eyeball’s sclera and the inside of the eyelids are covered with thin conjunctiva, and the outside of eyeball is connected to small muscles. Behind the eyeball is the optic nerve, which contains the blood vessels that supply blood to the eyeball.
Light transforms images
When the external image enters eyeball with light through the pupil, it stimulates the receptor cells on the retina. The cells transmit photoelectric signals to the surrounding connection cells. The processed nerve impulses are finally transmitted to the visual center of the brain via the optic nerve to form an image.
Pupil enlargement and constriction
The size of the pupil is controlled by the sphincter and dilator muscles in the iris. When the eyes are exposed to bright light, the sphincter muscles contract, and the pupils become smaller. On the contrary, when the light is dim, the dilator muscle contracts, causing the pupil to dilate.
Eye movement
The muscles of the eyeball are attached to different directions of the eyeball. When the oculomotor muscle in a certain place contracts, it will pull the eyeball to move in that direction. Sometimes complex eye movements require more than two oculomotor muscles to contract together.
In terms of prevention
Paying attention to eye hygiene is one of the important ways to prevent eye diseases. Do not overstrain your eyes, do not read in dimly lit areas, wear eye protection glasses when working under strong light, and do not abuse gauze to cover your eyes or Indiscriminate use of eye drops.
