In today's society, the problem of myopia among teenagers is becoming increasingly serious and has become a highly concerned public health issue. Myopia not only brings many inconveniences to teenagers' learning and life, but may also have long-term impacts on their future career choices and physical and mental health. Therefore, understanding the causes of myopia in adolescents and taking effective preventive measures is of great significance.
1、 The causes of adolescent myopia
(1) Genetic factors
Genetic factors play an important role in the occurrence of adolescent myopia. If both or one parent is nearsighted, the probability of their child developing myopia will significantly increase. Research has shown that the genetic predisposition to high myopia (myopia degree greater than 600 degrees) is more pronounced. For example, if both parents have high myopia, the incidence of myopia in their children may be as high as 80% or more.
（2） Environmental factors
1. Long term close eye use
During the learning process, teenagers need to constantly adjust the focal length of their eyes by reading, writing, and using electronic devices for a long time, which puts the ciliary muscle in a tense state for a long time and can easily lead to myopia. For example, some students do homework and read books for several hours every day without paying attention to rest, and their eyes cannot relax, which eventually leads to myopia.
2. Poor eye posture
Improper sitting posture, reading on the stomach, playing with mobile phones while lying down, etc. can cause the eyes to be too close to the book or screen, increasing the burden on the eyes. For example, some children like to read books with their heads tilted, which can cause inconsistent adjustment of their eyes and easily lead to visual fatigue and myopia.
3. Lack of outdoor activities
The reduction of outdoor activity time is an important factor leading to myopia in adolescents. Sunlight can stimulate the retina to secrete dopamine, which can inhibit eye growth and prevent myopia. However, many teenagers nowadays spend more time indoors and lack sufficient sunlight exposure. According to a survey, teenagers who spend less than 2 hours a day outdoors have a significantly higher incidence of myopia compared to those who spend sufficient time outdoors.
4. Improper lighting
Excessive or insufficient light can cause damage to the eyes. Reading and writing in dimly lit environments requires more effort to adjust the eyes, which can easily lead to myopia. And strong light stimulation can also make the eyes feel uncomfortable and affect vision. For example, reading under streetlights or using electronic devices in strong light are not conducive to eye health.
（3） Dietary factors
1. Nutritional imbalance
Lack of vitamins A, B1, B2, C, as well as trace elements such as calcium and zinc, can affect the normal development and function of the eyes, increasing the risk of myopia. For example, vitamin A deficiency can lead to night blindness, while calcium deficiency can reduce the elasticity of the eyeball wall, making it easier to elongate the eyeball axis and form myopia.
2. Excessive intake of sweets
Excessive intake of sweets can consume vitamin B1 in the body, affect the development of the optic nerve, and also lead to a decrease in blood calcium, affecting the toughness of the eyeball wall and making the eyeball axis easy to elongate, thereby promoting the development of myopia.
2、 Prevention of myopia in teenagers
(1) Cultivate good eye habits
1. Maintain correct reading and writing posture
Achieve "one fist, one foot, one inch", that is, one fist away from the table, one foot away from the book (about 33 centimeters), and one inch away from the pen tip (about 3 centimeters) when holding the pen.
2. Control eye usage time
Follow the "20-20-20" principle, which means every 20 minutes of eye usage, look towards a distance of 20 feet (about 6 meters) for 20 seconds to give your eyes sufficient rest.
3. Avoid improper eye posture
Do not lie down to read or play with your phone, and do not read or use electronic devices while walking or riding.
（2） Increase outdoor activity time
Ensure at least 2 hours of outdoor activity per day to fully expose your eyes to sunlight. You can choose some outdoor sports such as running, playing ball, flying kites, etc.
（3） Improve the visual environment
1. Maintain sufficient and uniform indoor lighting
When reading or writing, choose a desk lamp with soft and stable lighting, and place it in the front left corner.
2. Choose appropriate tables and chairs
The height of the tables and chairs should match the height of the child to ensure a comfortable sitting posture.
（4） Reasonable diet
1. Balanced nutrition
Eat more foods rich in vitamins A, B1, B2, C, as well as trace elements such as calcium and zinc, such as carrots, spinach, fish, eggs, dairy products, etc.
2. Control the intake of sweets
Reduce the consumption of high sugar foods such as candies, cakes, and beverages.
（5） Regular vision check ups
It is recommended that teenagers undergo vision check ups every six months to promptly identify problems and take corresponding measures. If you are already nearsighted, you should wear appropriate glasses or undergo other treatments according to the doctor's advice.
3、 Summary
The causes of adolescent myopia are multifaceted, and genetic factors cannot be changed, but environmental and dietary factors can be improved through our efforts. Preventing myopia requires the joint attention and efforts of adolescents themselves, parents, schools, and society. Only by cultivating good eye habits, increasing outdoor activity time, and maintaining a reasonable diet can teenagers effectively prevent myopia and have a clear and bright future.