Guidelines for novel coronavirus pneumonia prevention during childhood and adolescence
During the novel coronavirus pneumonia epidemic, the use of electronic products increased and outdoor activities decreased, which increased the risk of myopia occurrence and progression. The novel coronavirus pneumonia prevention and Control Bureau was set up by the disease control bureau of the national health and Health Commission, Medical University Of Anhui School of health management, Beijing City Center for disease control, Shanghai Eye Disease Prevention and Treatment Center, and the center for eye sight. The situation of class resumption should be updated and adjusted in time.
1、 Prevention of myopia during online learning
（1） Electronic products use time requirements.
During online learning, the use time of electronic products for online learning should be limited.
1. Online learning time is no more than 2.5 hours per day for primary school students and no more than 20 minutes for each time; 4 hours per day and no more than 30 minutes for middle school students.
2. Reduce the video time except for online learning. In addition to the online education time arranged by the education department, the accumulated video time for other purposes shall not exceed 1 hour per day.
（2） Electronic product selection and placement requirements.
During the online learning period, special attention should be paid to eye hygiene, and electronic products should be reasonably selected and used to ensure scientific eye use.
1. Selection of electronic products
(1) Choose large screen electronic products as much as possible, and the priority is projector, TV, desktop computer, notebook computer, tablet computer and mobile phone.
(2) Electronic products with high screen resolution and suitable definition should be selected.
(3) When using electronic products, adjust the brightness to make your eyes feel comfortable. Do not over light or dark.
2. Placement of electronic products
(1) Electronic products should be placed away from the window and direct light, the screen side to the window to prevent the screen reflection from irritating the eyes.
(2) When using the projector, the viewing distance should be more than 3 meters; when using the TV, the viewing distance should be more than 4 times of the diagonal distance of the screen; when using the computer, the viewing distance should be more than 50 cm (about one arm length).
(3) When placing electronic products (such as computers), make sure that the upper end of the screen is level with the eye level line of sight.
（3） Reading and writing posture.
During the online learning period, children and adolescents should timely adjust their holiday learning arrangements to meet the following reading and writing requirements.
1. When listening on the screen, keep the shoulders relaxed, the upper back extended, the upper arm and forearm form a 90 degree angle, the wrist is relaxed, and breathe regularly.
2. When watching the video screen to write homework, the reading and writing posture should be "one foot, one fist, one inch": eyes are about one foot away from the book (about 30cm), the body is about one fist away from the desk, and the fingers are about one inch away from the tip of the pen.
3. Don't lie on the bed or sofa and Study on the screen.
（4） Relax your eyes.
During online learning, increasing active rest time can not only relax ciliary muscles, alleviate eye fatigue, but also slow down brain fatigue, improve learning efficiency and relieve tension.
1. Continuous video learning time more than 20-30 minutes, at least 10 minutes of active rest.
2. In the process of video learning, consciously close and open your eyes slightly, rotate your eyes up and down, and relax your eyes.
3. In addition to online learning, stretch your waist and arms, walk indoors, do gymnastics, squat exercises, sit ups, etc.; do eye exercises after cleaning your hands; stand in front of the window, balcony or door and look at the distance (more than 6 meters).
4. During the period of home isolation, you can take a bath of sunshine through the balcony, window edge or your own courtyard to get in touch with natural light.
（5） Lighting and lighting requirements.
During the epidemic period, the family is the main place for children and adolescents to live and study. The lighting and lighting condition of the family is very important to the eye hygiene of children and adolescents.
1. Place the desk beside the window so that the long axis of the desk is vertical to the window. When reading and writing in the daytime, the natural light should be from the opposite side of the writer.
2. If there is not enough time line for reading and writing in the daytime, desk lamp can be placed on the desk for auxiliary lighting, and the position is in front of the opposite side of the writer.
3. When reading and writing at night, desk lamp and ceiling lamp should be used at the same time, and the lamp should be placed correctly.
4. The household lighting source should adopt three primary color lighting equipment, and the color temperature of table lamp should not exceed 4000K.
5. The naked lamp should not be used in the family lighting, that is, the lamp tube or bulb can not be used directly, but the lamp tube or bulb protected by lampshade should be used to protect the eyes from glare.
6. Avoid placing glass panels or other objects that are prone to glare on the desk.
（6） Home desk and chair adjustment.
In order to ensure that children and adolescents can maintain correct reading and writing posture at home and reduce learning fatigue, parents should provide children with appropriate desks and chairs.
1. For families with adjustable desks and chairs, adjust the height of desks and chairs according to the principle of "sitting on the chair / stool with the thighs perpendicular to the lower leg, the upper arm sagging when the back is straight, and the elbow is 3-4cm below the table top".
2. For families without adjustable desks and chairs, adjust them according to the above principles. If the table is too high, use a higher chair as far as possible, and put a foot pad under the foot, so that the foot can be flat on the foot pad, and the thigh is vertical to the leg. When the table or chair is too low, cushion the table or chair.
（7） Arrange your daily life reasonably.
During the epidemic period, families should create a good atmosphere, and parents should help their children to maintain their learning and life rhythm, and ensure that their children have regular work and rest, adequate sleep and moderate physical activity.
1. Ensure enough sleep time every day. Pupils should have 10 hours, junior high school students 9 hours and senior high school students 8 hours.
2. When studying at home, we should avoid bad habits such as sleeping late and getting up late, so as to reduce the interference to the biological clock.
3. Parents should urge their children to keep their learning and life rhythm, carry out more interactive fun games and enhance parent-child communication.
4. Children and adolescents should help their parents to do a proper amount of housework every day, such as cleaning, cleaning the room, washing dishes, cooking, etc.
5. Parents can arrange their children to have outdoor activities in the community, such as rope skipping, racking, badminton, aerobics and other activities.
（8） Pay attention to hand hygiene and eye health.
Hand hygiene is an important factor to ensure eye health. Washing hands frequently can prevent virus and bacteria infection and effectively prevent eye infectious diseases.
1. Wash hands before and after meals and after going home. Use "7-step washing method" and ensure more than 20 seconds.
2. Don't rub your eyes.
3. If the eyes appear dry, foreign body feeling, burning, itching, photophobia, red eye, eye pain and other symptoms, should stop the video behavior. If symptoms cannot be relieved, go to the hospital if necessary.
4. When the symptoms related to myopia are found, such as crooked head vision, frequent squinting and eye winking, they should take timely rest and exercise, and go to the hospital if necessary.
2、 Prevention of myopia after returning to school
After returning to school, we should continue to cultivate and maintain good eye habits. With the gradual normalization of classroom teaching, schools should reduce the use of electronic products, restore eye health exercise system, provide good lighting conditions, timely adjust desks and chairs, and increase outdoor activities under natural light conditions.
（1） Develop good eye use behavior.
Good eye use behavior can reduce eye fatigue, reduce eye over adjustment, and continue to maintain good eye use behavior after returning to school.
1. Keep reading and writing posture of "one foot, one fist and one inch".
2. After 30-40 minutes of reading and writing time, take a 10 minute active rest and look into the distance.
3. Don't read books and mobile phones when walking, in direct sunlight or in the turbulent carriage.
（2） Reduce the use of electronic products.
Long term use of electronic products can cause eye discomfort and increase the risk of myopia. After returning to school, children and adolescents should reduce the use time of electronic products in time.
1. Teaching with electronic products should not exceed 30% of the total teaching time. In principle, paper homework should be used.
2. The use of electronic products for non learning purposes should not exceed 15 minutes at a time, and should not exceed 1 hour in total every day.
3. The younger children should spend less time using electronic products. Preschool children under 6 years old should avoid exposure to mobile phones, computers and other video environment as far as possible, and parents should play an exemplary role.
（3） Eye exercises.
It is of positive significance to carry out eye exercises regularly for the prevention of myopia.
1. Clean hands thoroughly before doing eye exercises.
2. "Eye relaxation exercise" and "eye love exercise" that do not contact the eyes can be selected.
（4） Classroom lighting.
Schools should provide good lighting conditions to ensure that students read and write enough time line.
1. The average illuminance of the desk top in ordinary classroom is not less than 300 LX and not more than 750 LX, and the illumination uniformity is not less than 0.7.
2. The blackboard of ordinary classroom shall be equipped with local lighting lamps, the average illumination shall not be less than 500 LX and not more than 1000 LX, and the illumination uniformity shall not be less than 0.8.
（5） School desks and chairs adjustment.
Desks and chairs should match the height of children and adolescents, and the desks and chairs in the classroom should be adjusted according to the standard of functional dimensions and technical requirements of school desks and chairs (GB / T 3976-2014).
（6） Increase outdoor activities under natural light conditions.
The most effective way to prevent and develop myopia is exposure to sunlight.
1. During the epidemic period, school physical education and 30 minute break should be carried out outdoors, with wrong time and peak, so as to increase the distance of students in sports activities.
2. Ensure more than 2 hours of outdoor activities every day, and advocate more than 3 hours of outdoor activities for myopia children and adolescents every day.
3. After returning to school, children and adolescents should go to and from school on foot, walk out of the classroom between classes, and finish homework after school in the afternoon to increase outdoor sunshine exposure time.