Hello everyone, I'll start with the conclusion of the experiment: cell phone>iPad>TV>projector.
I just came to Knowledge and realized that everyone is concerned about children's eyesight. But there are many factors involved in impaired vision, and no one can come up with a shred of evidence based on real-life scenarios, let alone experimental data.
It wasn't until the other day that I finally saw a real-life experiment. That is, three medical professionals from the Zhejiang Provincial Eye Hospital (Wenzhou Medical University Affiliated Optometry Hospital, the national standard logarithmic visual acuity chart drafting unit), took their own children to do an experiment.
Unfortunately, because of poor dissemination, not many people are aware of this 2014 experiment. So I'm putting the experiment here in the hope that it will help more parents . At the end I will also put a screenshot of the official news at the time, so you can search for confirmation of this experiment.
OK, here is the experiment.
Experimenters:
Chen Yan, deputy director of the Optometry Center at Zhejiang Eye Hospital, daughter Hip Hip, 6 years old;
Eddie Zhang, Department of Public Welfare Medicine at Zhejiang Eye Hospital, daughter Gaga, 6 years old;
Yang Jie, director of the Information Center at Zhejiang Eye Hospital, son Gogo, 6 years old.
Experimental Methods
The 3 children had 5.0 visual acuity in both eyes, and over the course of 4 days, the ophthalmologists allowed the 3 children to use, and watch, the iPhone, the iPad, the 42-inch LCD TV, and the projector.
They determined how much damage they did to the children's vision by comparing the before-and-after changes in their refractive error, tear film breakup time, and number of blinks in a minute.
Special Note
The changes in vision for the three children were short-lived, and with a period of relief, they returned to normal, and were absolutely safe for the children's eyes.
Final results
iPhone and iPad are far more destructive to children's vision than TV and projection.
Test 1: Refraction
Test method: Playing iPhone for 20 minutes
Test 1 result: the average visual acuity of the three children is close to mild pseudomyopia status<
Experiment details: Diopter is often referred to as myopia, hyperopia, and can directly reflect the level of vision of the eyes. Over the course of 4 days, 3 children used an electronic device for 20 minutes a day. However, before the experiment, all 3 children did far-sightedness to keep their eyes in a relaxed state. After 20 minutes of continuous use of electronic products, the eyes do not do any relaxation adjustment, immediately test the refraction, the results are as follows ---
Dr. Chen Yan said: a short period of time myopia increased by 50 degrees, which is considered pseudomyopia, as long as the eyes immediately look away to relax the adjustment, the eyesight will be immediately The first time I saw this, it was a very good thing that I was able to see it. However, if you have a regular 50 degree, it will become a true myopia 50 degrees, this myopia state can not be restored.
Test 2: Tear film breakup time
Test: Playing iPad for 20 minutes
Test 2: Tear film breakup time is comparable to dry eye patients with dry eye.
Experiment details:
After the 3 kids played with the electronics for 20 minutes, the doctor immediately put some drops into their eyes to see how long the tear film would last before it broke down under the effect of the drops. In general, the shorter the tear film lasts, the more tired the eyes are. The results are as follows ---
Dr. Chen Yan said the tear film, which is a film formed by tears in the eye, can moisturize the eyes and relieve fatigue. Tear film rupture time is an important indicator of visual fatigue. The general tear film rupture time is 8-10 seconds, below this value, it shows that the eyes are in a state of tension, easy eye fatigue. "In the clinic, if the eyes do the test in a relaxed state, the tear film rupture time is within 5 seconds, is an important basis for diagnosing patients with dry eye."
And in the experiment, the tear film ruptured in 5 seconds for all three children after 20 minutes of iPad play, which is significantly lower than normal.
Test #3: Blink count
Test #2: How attentive are you to playing with the iPad?
Project three results: 1 minute blinking only 4 times, the eyes are in a state of tension
Experiment details: The number of blinks, which can reflect the degree of stabilization of the tear film function. Usually, the normal human blinking frequency is 15-20 times / minute, below this value indicates that the eyes are in a state of tension, which can easily lead to eyestrain, dry eyes, vision loss.
Before the experiment, the doctors talked to three children and secretly recorded the number of blinks under the state of eye relaxation without the children's knowledge. Then, they recorded the number of blinks per minute while the kids were using electronics. The results were as follows--
In this experiment, the three children were surprised at how much they were "focused" on their phones and tablets--the number of times they blinked was reduced by a factor of two to three.
Clinically, the number of blinks reflects the degree of stabilization of tear film function. Typically, normal blinking frequency is 15-20 times / minute, less than this value indicates that the eyes are in a state of tension, which can easily lead to eye fatigue, dry eyes, vision loss.
Dr. Chen Yan said, It is clear that the destructive power of iPhones and iPads on a child's vision is much higher than that of TVs and projectors. Combined with clinical and this experiment, in general, a child watching a cell phone for ten minutes of eye fatigue is equivalent to watching TV for 30 minutes.
The combined data shows that the ranking of display device damage that affects a child's vision (refraction, tear film breakup time, number of blinks) is: iPhone> iPad> TV> projection.
Hou Lijie, deputy director of the Optometric Diagnostic and Treatment Center of Zhejiang Provincial Eye Hospital, introduced that, genetic factors aside, the cause of myopia is mainly due to the eye environment. This environment includes eye distance, time, posture, light and so on.
Related Knowledge:
1, the viewing distance is preferably 3-5 times the diagonal of the screen of the electronic product, to the iPad, for example, the screen diagonal is about 25 centimeters, then the viewing distance should be at least 75 centimeters. It's hard to see, but the farther away the better.
2, viewing time, it is recommended that children (2 6 years old) should not operate electronic video products for more than 20 minutes each time, and the cumulative time per day is recommended to be no more than 1 hour.
3. The screen of the computer is slightly lower than 10-15 degrees below our horizontal line of sight. The area of the eye exposed to the air is significantly larger, the tear film destruction time is shortened, more likely to produce visual fatigue. (I understand that all kinds of screens are a reason)
4, the ambient light affects the eye pressure, the eye pressure increases, the eyeballs will become larger, the more prone to myopia. So be sure not to watch electronic devices in too dark an environment, projectors such as products, you need to buy real lumens higher.
Knowledge about eye protection is more **** knowledge, you can go to another understanding.
Original title: How much difference is there between the destructive power of iPhone, iPad, and TV on children's eyesight? --- Metro Express