Is the lens transparent? How many parts are the visual organs divided into?

The difference between people lies in cognition. The same eyes, the same world, but everyone sees a different world. Why?

One world, different horizons.

In the era of attention economy, commercial conspiracies or public schemes are trying their best to attract people's visual attention. More and more people's eyes are locked by the screen, working on the computer screen, socializing, playing games, shopping, watching the news and staring at the mobile phone screen ... Our eyes are experiencing unprecedented challenges and torture. Eyes determine the world in front of us and also affect our future.

The eyes are the windows of the soul and the important organs to connect people with the outside world. Light or dark, wonderful or never seen, depends on whether you have a pair of healthy eyes.

Open the window and let the sun shine in. Only by loving your eyes can you feel this beautiful world. Research shows that 90% of the five senses of eyes, ears, nose, tongue and body come from eyes. Therefore, we need to know more about eyes.

First, the structure and function of eyeball

The eye is a spherical organ filled with transparent substances, so it is called eyeball. The eyeball is divided into three parts from front to back: refractive system, supporting system and photosensitive imaging system.

Structure and function diagram of eyeball

1, refractive system: including cornea, aqueous humor and lens.

Cornea: located in the center of the anterior pole of the eyeball, slightly protruding forward, it is the most transparent part of the eye and provides the greatest refractive power for the imaging of the eye. Cornea has no blood vessels, and can only get nutrition and oxygen through aqueous humor and tears.

Eye chamber: the cavity between the cornea and the lens, which is filled with aqueous humor. Aqueous humor is a colorless and transparent liquid, and its main functions are: (1) providing nutrition and oxygen to intraocular tissues and discharging its metabolites; (2) maintaining intraocular pressure; ⑶ It is one of the refractive stroma and has refractive effect.

Lens: Located between iris and vitreous body, it is a biconvex lens, which is composed of multiple layers of fibers, transparent and elastic. When the curvature of the lens is too large, the object image falls in front of the retina, forming myopia; When the curvature of the lens is too small, the object image falls behind the retina, forming hyperopia.

Because there are no blood vessels in the cornea and lens, the nutrient supply and metabolic waste discharge are realized through the circulation of aqueous humor, so the smooth circulation of eyeball microcirculation is very important for vision health.

2. Eye support system: vitreous body

Vitreous body is a colorless and transparent colloidal substance, which is filled in the eyeball frame behind the lens and supports the whole eyeball, and is covered with a transparent vitreous membrane. The vitreous body not only refracts light, but also supports the retina. Vitreous body is composed of 98.5% water, salt, a little fat and hyaluronic acid. There is no vascular tissue in it, and its nutrients and metabolites are exchanged through the outer glass membrane.

3. Photosensitive imaging system: retina

The eye wall consists of three layers of membranous tissue, the outermost layer is fibrous membrane, the middle layer is vascular membrane and the innermost layer is retina.

Fibrous membrane is composed of dense connective tissue, thick and tough, and is the shell of eyeball.

The middle layer is the vascular membrane, which is located between the fibrous membrane and retina. It is rich in blood vessels and pigment cells, which provide nutrition for the tissues in the eyeball and form a dark environment, which is beneficial to the sensitivity of the retina to light and color.

The retina is a transparent film, as sensitive as camera film. There are two kinds of visual cells in the retina: one is called cone cells, which can feel strong light and distinguish colors; The other is called rod cells, which can feel weak light. There is an area with a diameter of 1.5 mm in the central area of retina at the back end of eyeball, which is the most sensitive part and is called macular area. Macular area is composed of cone cells, which is the most concentrated place.

There are more than 1 100 million photoreceptor cells in the retina. After being stimulated by light, the photoreceptors undergo photochemical reactions, which are transformed into nerve impulses and introduced into the visual center of the brain. After comprehensive analysis, the advanced center produces vision. Any scenery we see is an image composed of photoelectric signals of more than 100 million visual cells.

Second, common eye diseases

The causes of ophthalmic diseases are various. This paper only discusses the common non-infectious and non-malignant visual system problems, such as visual fatigue, blood circulation disorder, visual malnutrition and so on. Please consult a professional ophthalmologist for other questions.

Cornea: dry eye, myopia, senile ring and other common problems.

Anterior chamber: glaucoma caused by water circulation disorder in the eye chamber, with elevated intraocular pressure;

Lens: The most common problem is cataract.

Cataract diagram

Vitreous body: the most common ones are blurred vision and floaters caused by vitreous turbidity;

Retina: The most common disease is macular degeneration. Typical symptoms are blurred vision, decreased vision, black shadow in front of eyes, distorted vision and finally blindness.

Third, the causes of common eye problems

For these common eye problems, people are often careless, and there are many misunderstandings in their understanding, which has caused great trouble to themselves. In fact, these eye problems can be prevented and recovered to a great extent, but more people do not take the initiative to assume their responsibilities.

Chronic eye diseases do not happen suddenly overnight, but are the result of long-term development and gradual accumulation. The causes of most eye diseases are concentrated in three aspects:

1, asthenopia, overuse of eyes. In today's information society. Work depends on the computer screen. When I go home to rest, I either watch TV or watch my mobile phone to play WeChat and games ... On average, people stare at the screen for more than 4 hours every day, and about 3 1% people watch their mobile phones for 5-8 hours. If the eye muscle spasm caused by visual fatigue is not relieved, the cornea and lens will be deformed, and the visual cell function of retina will also cause permanent damage;

2, systemic blood circulation disorder and eye microcirculation disorder. No matter the cornea, lens or vitreous body, there are no blood vessels to supply nutrition. When the body suffers from chronic diseases (diabetes, hypertension, hyperlipidemia, arteriosclerosis, etc.). ) cause systemic or ocular circulatory disorders, and the function of ocular tissues will be weakened due to insufficient nutrition supply, and the damage will not be repaired. At the same time, because the metabolic waste can not be removed in time, the related tissues will continue to be damaged and the structure will age, and eventually cataract, floaters, macular degeneration and macular degeneration will occur.

3. Visual malnutrition. Nutrients to maintain eyeball health include VC, VA, unsaturated fatty acids, lutein, anthocyanin and zeaxanthin, among which lutein, anthocyanin and zeaxanthin are essential nutrients for visual cells, which cannot be synthesized in vivo and must be fully supplied in diet to ensure the health of visual cells.