We often hear words such as vision 1.0, 0.8 and myopia 100 degrees, 200 degrees in our daily lives, but in fact, vision 1.0 does not mean that there is no myopia, and vision 0.8 does not mean 100 degrees of myopia.
The relationship between vision and myopia is like the relationship between weight and obesity standards. If a person weighs 200 catties, it does not mean that he must be obese. We also need to judge according to his height-a person with a height of 2 meters is not fat at 200 catties. , But if a person of 1.5 meters is 200 catties, he is severely obese.
Therefore, when we look at our eyesight, we also need to analyze it in combination with personal factors. For example, a visual acuity of 0.8 for a 4 or 5 year old child is normal because the child has a certain reserve of farsightedness. Adults have mild myopia if their vision is 0.8.
True and false myopia
[True myopia] refers to the refractive error that occurs when the axis of the eye becomes too long.
[Pseudo-myopia] It can be said to be a kind of “accommodative myopia”, which is a state of eye fatigue, which refers to the accommodative spasm of the ciliary muscle after excessive use of the eye.
On the surface, pseudo-myopia also blurs the distance and clearly sees near, but there is no corresponding diopter change during mydriatic refraction. So why is it not clear from a distance? This is because the eyes are often used incorrectly, the ciliary muscles continue to contract and spasm, and they cannot get the rest they deserve, and the lens becomes thicker. In this way, the parallel light enters the eye, and after the thickened lens is flexed, the focus falls to the front of the retina, and it is natural to see things in the distance.
False myopia is relative to true myopia. In true myopia, the refractive system of the emmetropia is in a static state, that is, after the adjustment effect is released, the far point of the eye is located within a limited distance. In other words, myopia is due to congenital or acquired factors that cause the anterior and posterior diameter of the eyeball to become longer. When parallel rays enter the eye, they form a focal point in front of the retina, causing blurred vision. And pseudo-myopia, it is part of the adjustment effect when looking at distant objects.
If the pseudo-myopia stage is not paid attention to, it will further develop into true myopia. Pseudo-myopia is caused by the ciliary muscle over-regulating spasm and unable to relax. As long as the ciliary muscle is relaxed and the lens is restored, the myopia symptoms will disappear; true myopia is It is caused by long-term spasm of the ciliary muscles, which oppresses the eyeball, causing the eyeball axis to elongate, and the distant objects cannot be imaged on the fundus retina.
Myopia prevention and control requirements
The “Health Requirements for the Prevention and Control of Myopia in School Supplies for Children and Adolescents” was released. This new standard has been determined as a mandatory national standard and will be formally implemented on March 1, 2022.
The new standard will include textbooks, supplementary materials, learning magazines, schoolwork books, examination papers, learning newspapers, learning materials for preschool children, and general classroom lighting, reading and writing homework lamps, and teaching multimedia for children related to myopia prevention and control. School supplies for teenagers are all included in the management, which stipulates that -
The characters used in the first and second grades of elementary school should be no less than 3 characters, the Chinese characters should be mainly in italics, and the line space should be no less than 5.0mm.
The characters used in the third and fourth grades of elementary school should be no less than No. 4 characters. The Chinese characters are mainly in Kaiti and Songti, and gradually transition from Kaiti to Songti, and the line space should not be less than 4.0mm.
The characters used in the fifth to ninth grades and high school should not be smaller than the small 4th character, the Chinese characters should be mainly Song style, and the line space should be no less than 3.0mm.
The supplementary words used in the table of contents, notes, etc. can be appropriately reduced with reference to the words used in the main text. However, the minimum words used in elementary school should not be less than 5 words, and the minimum words used in junior high school and high school should not be less than 5 words.
The font size of preschool children’s books should not be less than 3, and italics are the main ones. The supplementary characters such as catalogues, notes, pinyin, etc. should be no less than 5th. The line space should not be less than 5.0mm.
Classwork books should be printed clearly and completely without obvious stains.
The learning newspaper should be uniform in ink color and consistent in depth; the imprints should be clear, and there should be no slurred characters that affect recognition; there should be no obvious watermarks.
Teaching multimedia should not show perceptible flicker, meet the blue light protection requirements, and the screen brightness should not be too large when used.
Family myopia prevention and control
The family is the main place for children and adolescents to live and study, and home lighting and lighting conditions are very important for children and adolescents’ eye hygiene.
1. Place the desk next to the window so that the long axis of the desk is perpendicular to the window. Natural light should enter from the opposite side of the writing hand when reading and writing during the day.
2. If there is not enough light when reading and writing during the day, you can place a lamp on the desk for auxiliary lighting, and place it in front of the opposite side of the writing hand.
3. When reading and writing at night, use the desk lamp and the room ceiling lamp at the same time, and place the lamp correctly.
4. Household lighting sources should use three-primary color lighting equipment, and the color temperature of table lamps should not exceed 4000K.
5. Naked lights should not be used for home lighting, that is, tubes or bulbs cannot be used directly, but tubes or bulbs with lampshade protection should be used to protect the eyes from glare.
6. Avoid placing glass plates or other items that are prone to glare on the desk.
Regardless of genetic reasons, some people say that the blue light of electronic screens can cause damage to the eyes, but in fact, blue light is everywhere in nature, and we do not damage our eyesight because of this. On the contrary, in an era without electronic products, many people still suffer from myopia. Therefore, the factors that really lead to the increase of myopia in adolescents are close and prolonged use of the eyes.
Use your eyes correctly and remember the “20-20-20″ formula: After looking at something for 20 minutes, divert your attention to an object 20 feet (6 meters) away, and hold it for 20 seconds.
Post time: Jan-26-2022