The eye is the window to the human soul and the only organ through which we see and know the world. Eyes are so important to everyone, so we have to understand our eyes and treat our eyes kindly.
1. The cornea-the lens
The cornea is the first pass where light enters the eyeball. Its refractive power is about 42D, accounting for 1/6 of the surface area of the eyeball, with a diameter of 11.5 mm, a center thickness of 0.6 mm, and a side thickness of 1 mm. Commonly known as “black eyeball”, in fact, it is transparent and flawless, only because the other part of the eyeball wall looks like the camera’s dark box when people look into the dark eye through this layer of transparent tissue, it will feel black. The corneal tissue is divided into 5 layers. : Epithelial layer, pre-elastic layer, stromal layer, a posterior elastic layer, endothelial cell layer. The corneal epithelial layer has very sensitive sensory nerve endings, but it is not sensitive to cold, so there is a saying of “the general who is not afraid of cold”. If the corneal epithelium is damaged, it usually heals without leaving a mark within 24 hours. If the cornea is severely damaged, it will leave a scar after healing, which is severely porcelain-white, like mildew on the lens, hindering vision.
Lens-a fully automatic zoom lens, located behind the pupil iris, is a biconvex lens. Normal people can see both near and far, depending on the adjustment of the lens. When looking far away, the ciliary muscle relaxes, the suspensory ligament tightens, the lens becomes flat, and the refractive power decreases; when looking closer, the ciliary muscle contracts and the suspensory ligament relaxes, the lens becomes convex by its own elasticity, and the refractive power increases. Through this adjustment, the light can be focused on the macula of the retina. If the light cannot be focused on the retina through adjustment, there is a refractive error. Light focusing on the retina is called myopia; after focusing on the retina, it is called hyperopia; it cannot be focused on a point, called astigmatism. If the accommodative function of the lens is dysfunctional, as in old age, the lens cannot become convex, which is called presbyopia, that is, presbyopia; if the lens becomes cloudy, it is called a cataract.
The retina plays a light-sensitive function and looks like the film in the camera. The most sensitive part is called the macula. And the retina is extremely thin, the structure is extremely complex, divided into 10 layers, the most important light-sensitive cells are cone cells and rod cells. The cone cells are mainly responsible for photopic vision and color vision, and the rod cells are mainly responsible for scotopic vision. The choroid-the camera’s dark box. The important thing is composed of blood vessels, so it also has the responsibility of nourishing the eyeball. The development of the eyeball: the development of the eyeball from small to large, it is the last phase before 3 years old, that is, the development from 18 mm after birth to 21 mm; before 15 years old, it is a slow phase, and the eyeball progresses to about 23 mm, to puberty Progress slowed down, almost stable after the age of 25.
4. Iris-the leaves of the aperture
Iris-the leaves of the aperture. If the light is too strong, the pupil sphincter in the iris contracts, then the pupil shrinks; the light becomes weak, the iris dilator muscles shrink, and the pupil becomes larger. According to the different pigments contained in the iris, the iris shows different colors. The iris of white people is less pigmented, which is grayish blue; the yellow trace is more pigmented, which is
brownish-yellow; the black color is the most pigmented, which is black.
5. Sclera-camera case
The white and opaque protects the internal structure of the eyeball, with a thickness of about 1 mm, occupying about 5/6 of the entire eyeball. It is also known as the white of the eye, it is indeed the sclera near the cornea and the transparent bulbar conjunctiva above it.
The eyes are a very important organ of the body and children should take care of their eyes when they are young. When there is eye discomfort, you should take your child to the doctor as soon as possible. For your convenience, you can find the relevant eye clinic online to make an appointment so that you can see the doctor as soon as you arrive at the hospital