When I first came to Zhihu, I found that everyone was very concerned about children's eyesight. However, there are many factors involved in vision impairment, and no one can produce evidence according to real life scenes, let alone experimental data.
Until the other day, I finally saw a real-life experiment. That is, three medical staff from Zhejiang Eye Hospital (the optometry hospital affiliated to Wenzhou Medical University, the drafting unit of national standard logarithmic visual acuity chart) made an experiment with their own children.
Unfortunately, because of poor communication, not many people know about this experiment in 20 14. So I put the experiment here, hoping to help more parents. Finally, I will put a screenshot of the official news at that time, and you can search to confirm this experiment.
Ok, here's the experiment.
Experimenter:
Deputy director of optometry center of Zhejiang Eye Hospital, daughter Xi, 6 years old;
Zhang Yun, daughter Gaga, 6 years old, Department of Public Medicine, Zhejiang Eye Hospital;
Yang Jie, director of Zhejiang Eye Hospital Information Center, has a 6-year-old son, Guoguo.
experimental method
The naked eye vision of all three children is 5.0. In four days, the ophthalmologist asked three children to use and watch iPhone, iPad, 42-inch LCD TV and projector respectively.
By comparing the changes of children's diopter, tear film rupture time and blink times in one minute, we can judge the degree of damage to children's vision.
Special instructions
The changes in the vision of the three children are short-lived, and they can completely return to normal after a period of relief, which is absolutely safe for the children's eyes.
The final result of the experiment
IPhone and iPad are much more destructive to children's vision than TV and projection.
Test item 1: diopter
Detection method: Play iPhone for 20 minutes.
The first result: the average vision of three children is close to mild pseudomyopia.
Experimental details: diopter is often called myopia and hyperopia, which can directly reflect the visual level of the eyes. For four days, three children used an electronic product for 20 minutes every day. But before the experiment, all three children made a vision to keep their eyes relaxed. After continuous use of electronic products for 20 minutes, the diopter was detected immediately without any relaxation adjustment, and the results were as follows-
Dr. Chen Yan said: The degree of myopia increases by 50 degrees in a short time, which is considered as pseudomyopia. As long as your eyes are relaxed, adjust them immediately and your vision will recover immediately. But if 50 degrees often appear, it will become true myopia 50 degrees, and this myopia state cannot be restored.
Test Item 2: Tear film rupture time
Detection method: play ipad for 20 minutes.
The second result: the tear film rupture time is equivalent to that of dry eye patients.
Experimental details: After three children played electronic products for 20 minutes, the doctor immediately dropped some liquid medicine into their eyes to observe how long the tear film could last under the action of the liquid medicine. Generally speaking, the shorter the tear film lasts, the more tired the eyes are. The results are as follows-
Dr. Chen Yan said that the tear film is a thin film formed by tears in the eyeball, which can moisten the eyes and relieve fatigue. Tear film rupture time is an important index to reflect visual fatigue. Generally, the tear film rupture time is 8- 10 second. Below this value, it means that the eyes are in a state of tension and are prone to eye fatigue. "Clinically, if the eyes are tested in a relaxed state, the tear film rupture time is less than 5 seconds, which is an important basis for diagnosing patients with dry eye."
In the experiment, after three children played iPad for 20 minutes, the tear film burst within 5 seconds, which was significantly lower than the normal level.
Test Item 3: Blinking Times
Test method: How focused are you on playing iPad?
The third result: 1 minute only blinks 4 times, and the eyes are in a state of tension.
Experimental details: The number of blinks can reflect the stability of tear film function. Under normal circumstances, the blink frequency of normal people is 15-20 times/minute. Below this value, the eyes are in a state of tension, which easily leads to eye fatigue, dry eyes and decreased vision.
Before the experiment, doctors chatted with three children and secretly recorded the number of blinks when the children relaxed their eyes without their knowledge. Then, when children use electronic products, they record the number of blinks per minute. The results are as follows—
In this experiment, three children were surprised by the "concentration" of mobile phones and tablets-the number of blinks was significantly reduced by two or three times.
Clinically, the blink times can reflect the stability of tear film function. Under normal circumstances, the blink frequency of normal people is 15-20 times/minute. Below this value, the eyes are in a state of tension, which easily leads to eye fatigue, dry eyes and decreased vision.
Dr Chen Yan said that obviously, the iPhone and iPad are much more destructive to children's vision than TVs and projectors. Combined with clinical practice and this experiment, under normal circumstances, the eyeball fatigue of children watching mobile phones for ten minutes is equivalent to watching TV for thirty minutes.
According to the comprehensive data, the injury ranking (diopter, tear film rupture time and blink times) of display devices that affect children's vision is: iPhone & gtiPad & gt TV > projection.
Hou, deputy director of optometry clinic of Zhejiang Eye Hospital, said that apart from genetic factors, the main cause of myopia is the eye environment. This environment includes eye distance, time, posture, light and so on.
Related knowledge points:
1, and the viewing distance is preferably 3-5 times the diagonal of the electronic product screen. Take the iPad as an example, the diagonal of the screen is about 25 cm, so the viewing distance should be at least 75 cm. Although it is difficult, try to stay as far away as possible when you can see clearly.
2. In terms of viewing time, it is suggested that children (2 6 years old) should operate electronic video products for no more than 20 minutes at a time, and the cumulative time per day should not exceed 1 hour.
3. The computer screen is slightly lower than our horizontal line of sight 10- 15 degrees. The area of eyeball exposed to air is obviously increased, the time of tear film destruction is shortened, and visual fatigue is more likely to occur. (I understand that all kinds of screens are the same)
4, ambient light affects intraocular pressure, intraocular pressure increases, the eyeball will become larger, the easier it is to be nearsighted. So don't look at electronic equipment in a dark environment. For this product, you need to buy a product with higher real lumen.
The knowledge about eye protection is more * * * knowledge, and you can understand it yourself.
Original title: What is the difference between the destructive power of iPhone, iPad and TV on children's vision? -Metropolitan Express