1, so that students can understand the causes of myopia and ways to protect their eyesight;
2. Correct students' bad eye habits and wrong eye exercises;
3. Educate students to develop good eye hygiene habits, do eye exercises seriously and exercise regularly.
Teaching essentials
1, look at the mystery of things.
2. Myopia and its mechanism.
3. The causes of middle school students' myopia.
4. Use your eyes scientifically to prevent myopia.
(A) to see the mystery of things
As the saying goes:? The eye is the skylight of the human soul. ? Eyes can make people get rich knowledge materials, enjoy the magnificent scenery of nature, express their inner feelings and reflect people's mental outlook. They are important organs for people to understand the objective world.
What do the eyes think? How do you see things?
The eye is like a camera, in which the cornea and lens are equivalent to the lens, the pupil is equivalent to the aperture, the choroid is equivalent to the black box, and the retina is equivalent to the negative. Eyes can turn objects in nature into images in the same way that objects in cameras form inverted images. Of course, the delicate eyes of the human body are many times more complex and precise than the camera, and it is not enough to tell the whole picture clearly in a few words. Here is a brief introduction to a process of human eye imaging.
Eyes see things entirely by the eyeball (that is, the eyeball). The white layer around the eyeball is called the sclera, which is the wall of the eyeball and is opaque. The transparent window in front of the eyeball is called cornea, from which light shines to the eyeball.
Looking in from the cornea, there is a black layer called iris, and there is a small hole called pupil in it to let light pass through. The iris acts like a curtain on a window. When the light strongly hurts the eyes, the iris is covered a little; When the light is not clear, open the iris a little.
After the light passes through the pupil, it continues to move inward and passes through the lens to reach the fundus. The lens is colorless, transparent, oblate, like a lenticular lens and a magnifying glass, and has a strong condensing effect, which can condense the light emitted by the object into an image. There is a thin film called retina in the fundus, which can feel the stimulation of light and connect with the optic nerve. After the light from the cornea passes through several channels and is concentrated into an image through the lens, the shadow light stimulates the retina, and the retina immediately reports the news to the brain through the optic nerve. People feel the light of this image and see the object clearly.
(B) the causes of myopia
1, normal eye accommodation. Normal eyes can not only see distant objects, but also see nearby objects through adjustment. When looking at distant objects, the eyes don't need to make any adjustments, and the objects are clear to the owner; When looking at nearby objects, only by adjusting, the lens becomes convex, thicker and the diopter increases can we see the objects clearly. The convex lens is caused by the contraction of the ciliary muscle, which relaxes the ligament of the suspended lens (that is, the lenslet).
2. Myopia and its mechanism. Myopia can clearly see near and near objects, but when looking at distant objects, because the objects fall in front of the retina, they can't see clearly. There are two kinds of myopia, one is called accommodative myopia, also called pseudomyopia, and the other is called axial myopia, also called true myopia. The lenses of primary and middle school students are elastic and adjustable. When an object (such as a book) is close to the eyes, it can be seen clearly. Because of their bad reading habits, or because of poor light and lighting conditions, they always put books near their eyes, and the ciliary muscles are always in a state of contraction. Over time, the ciliary muscles continue to spasm. Once you look at distant objects, the ciliary muscles can't relax and the lens can't return to its original plane state. This condition is accommodative myopia. Myopia of primary and secondary school students mostly belongs to this type.
At this time, if you pay attention to protecting your eyesight and eliminate the factors that cause accommodation tension, your eyesight can be improved or returned to normal.
3. Causes of myopia
(1) The distance between the eyes and the book is too close, the reading and writing posture is incorrect, and the eyes are used for too long. We know that the eyes need to be adjusted when looking at close objects, and the convexity of the lens should be increased to increase the refractive power. If you look at the object for too long, the lens will be in a state of high adjustment for a long time, causing fatigue of the ciliary muscle.
(2) The light is too weak or too dark, and the illumination is not suitable for eyes. Generally speaking, the illumination required for reading and writing should be no less than 100 lux.
(3) The reading posture is incorrect, or the reading place is inappropriate. Some children like reading while lying down, reading by car and walking. When reading while lying down, the light is often insufficient, the posture is skewed, and the book is not easy to put straight. In order to read the handwriting clearly, it is necessary to put the book closer, which will strengthen the adjustment of the eyes and increase the burden on the eyes. If you have this bad reading habit for a long time, it is easy to cause myopia.
(4) the existence of genetic tendency. Generally, high myopia (more than 6 diopters, commonly known as 600 degrees) is mostly caused by genetic factors. However, myopia caused by genetic factors accounts for a small proportion of total myopia.
(3) Scientific use of eyes to prevent myopia
Myopia is a common disease in primary and secondary schools, and it is also the main cause of poor eyesight. To prevent children's myopia, we must start from many aspects and take comprehensive measures to get results.
1, control reading time
Generally speaking, the younger you are, the shorter the continuous reading and writing time should be. Whenever you read and write for 40-55 minutes, you should rest for about 10 minutes, look at the clouds in the sky (during the day) or the stars (at night), look at the distant trees or buildings, or take a walk or play games outdoors to rest your eyes.
2. Keep correct reading and writing posture.
Children should develop correct posture when reading and writing. Sit up straight, don't stand up straight, and don't lie flat. It is best to make an angle of 30 -40 degrees with the desktop, so that the book is perpendicular to the line of sight. Keep the distance between the eyes and the book about one foot, and the distance between the chest and the edge of the table about one foot. Don't squint, don't write with your head tilted, don't read on your desk, and don't read in bed.
3. Adjust the reading light.
Parents and teachers should create good reading and writing conditions for their children. Fluorescent lamps should be used for collective evening self-study in classrooms. Personal self-study at night at home, the light bulb can not be less than 25 watts; It is best to use local lighting, such as installing a desk lamp, and the lamp mouth should be equipped with a lampshade to avoid the stimulation of white light to the eyes. The light should come from the left front to avoid being blocked or weakened by other objects. Reading and writing during the day should be done indoors, near the window, but not in direct sunlight.
4. Don't read while walking or riding a bike.
Walking or reading by car is one of the reasons for myopia.
5, strengthen nutrition and exercise, enhance physical fitness.
On the surface, it seems that strengthening nutrition, exercising and strengthening physical fitness has nothing to do with eyesight. In fact, this is one of the important measures to prevent myopia.
6, insist on doing eye exercises
Eye exercises are scientifically prepared by the principles of Chinese massage, acupuncture and acupoint massage. By massaging nearby acupoints, weak stimulation can cause conditioned reflex, thus eliminating the tension of eye adjustment and assembly, strengthening eye nutrition and tissue metabolism, improving and promoting blood circulation, and maintaining normal physiological functions of eyes.
7. Pay attention to protecting your eyesight when watching TV.
When watching TV, you'd better sit in front of it. If you sit on the side, the observation angle should not be less than 45 degrees. The distance between people and the TV should be 5-7 times the size of the TV screen, generally about 2 meters; The height of the TV should be the same as the horizontal line of the eyes; Keep the TV image clear and stable, neither too bright nor too dark; When watching TV, it is best to turn on a 3-watt or 5-watt fluorescent lamp indoors, and the position should be behind the audience so that the place will not be too dark; Every 40 or 60 minutes of watching TV, you should take a rest with your eyes closed, or take off your eyes and look around during the intermission of TV program exchange, get up and do other things, exercise and let your eyes rest.
8. Looking at green objects is good for your eyes.
After intense and busy study, when we look up at the green crops and trees outside the window or in the distance, our nervous nerves suddenly feel relaxed and our tired eyes feel very relaxed. This is not only because looking at the distance relaxes the adjustment of the eyes, but also because turquoise has a soothing effect on the eyes.
Students, try to see more green trees, green crops and green grass in class or homework, which is good for your eyes.
Teaching suggestion
1, explain in simple terms the importance of maintaining eyesight and the formation of myopia.
2, according to the students' eyesight or specific examples, correct bad eye habits and wrong actions of doing eye exercises.
3. In teaching, we should pay attention to the application of modern teaching technology, make teaching slides or videos, enhance the intuitive effect, improve students' interest in learning and ensure the quality of teaching.
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