Just one look caused permanent blindness

I was curious when I saw my classmates playing with laser pens. Just as I got closer, a beam of red light hit my eyes directly and I lost my sight in an instant. Half a month ago, Peng Zhihua, director of the fundus department of an ophthalmology hospital in Wuhan, treated a 10-year-old boy whose right eye was burned by a laser pen. This was the fourth child burned by a laser pen that he had treated this year. Unfortunately, without exception, these children suffer permanent vision loss.

"Most multimedia lectures now use laser pens, and the biggest fear is that they might accidentally shoot into the audience's eyes." At the National Eye Fundus Disease Prevention and Control Summit Forum held recently, Professor Li Xiaoxin, the country's top eye fundus disease expert, mentioned twice that he was "extremely nervous" when using a laser pen. Many top ophthalmologists at the scene called for: Please warn children not to use laser pens as toys to shine on each other!

The boy was exposed to the radiation for a few seconds and suffered permanent damage

Half a month ago, a 10-year-old boy named Pengpeng came to Peng Zhihua's clinic. "My classmate's laser pen shone on my eyes for a few seconds, and it was like a big round black dot blocked my eyes. I couldn't see anything." The boy said in a low voice with his head down.

Peng Zhihua's heart tightened and he quickly arranged for a check-up. The results showed: the visual acuity of the left eye was 1.2, the visual acuity of the right eye was only 0.2, and there was a round burnt scar on the macular area of ​​the right fundus. Pengpeng is a third grader in a primary school in Huangpi. During break, several boys in the class took out laser pens to play with them, competing to see who could shoot the farthest. Pengpeng thought it was interesting and just as he moved closer, a beam of red light shone directly into his eyes.

He was stunned for a few seconds and felt as if his right eye was blocked by a large round black spot. It was not until the next day when Pengpeng found that the black spots would not go away, and he told his mother in fear. "Laser damage to the macular area is permanent and irreversible, and modern medicine is powerless to cure it," Peng Zhihua told Pengpeng's mother regretfully.

"Last year, when laser pens just became popular, we encountered quite a few children whose eyes were burned by laser pens and caused loss of central vision." Cao Yang, a professor of ophthalmology at a certain hospital, said that although the eyes will instinctively close reflexively when encountering strong light, these few seconds are enough to cause irreversible damage to the delicate macula.

Central vision is irreversibly damaged

"When laser enters the eye, the first area to be injured is the macula." Peng Zhihua explained that when the eyes are looking at things, the macula is the first to "capture" the object, and focusing is also accomplished by the macula. The macula located in the center of the retina is the center of human vision and is also the area with the highest light sensitivity and the most vulnerable.

Once this area is burned by the laser, it will feel as if a large round black spot is blocking your vision. Peng Zhihua said figuratively that looking at things is like looking at a "total solar eclipse", with black in the middle and bright around the edges. The worst thing is that unlike the cornea and lens which can be transplanted and replaced, this kind of damage cannot be recovered through any surgery or treatment.

Fu Xuan'an, director of the ophthalmology department of a certain hospital, reminded us: "Often by the time we notice the glare and react by closing our eyes, the damage has already been done."

Laser has become an important diagnostic and treatment method in ophthalmology. Will this treatment damage vision? Liu Hengming, vice chairman of the Hubei Laser Medicine Association and professor of ophthalmology at a certain hospital, said frankly, "When we do laser treatment, the most important thing is to absolutely avoid the macular area. Not only the patient's macular area should be protected, but the doctor should also wear protective glasses."

A 1 milliwatt laser is enough to burn a child's eyes

In March this year, the General Administration of Quality Supervision, Inspection and Quarantine issued the "Product Quality Safety Risk Warning and Consumer Tips for Laser Pens and Children's Laser Guns", stating that it is not appropriate to buy laser pens for children to use as toys, and consumers should avoid shining laser pens on human eyes, skin, clothes and other places when using laser pens.

The document requires the implementation of a "grading system" for the sale of laser pens: the degree of hazard is ranked from low to high as follows: Class 1, Class 1M, Class 2, Class 2M, Class 3R, Class 3B, Class 4, and all types of laser pens must be marked with category. Among them, laser pens in toys should meet the Class 1 laser radiation power limit requirements, that is, the output power must be less than 0.4 milliwatts.

Professor Li Zhengjia from the School of Optics and Electronic Information at Huazhong University of Science and Technology has been researching medical lasers for nearly 40 years. He told reporters that laser is parallel light, has a long emission distance, a small divergence angle, and will "move forward courageously" after being emitted.

Under the action of the convex mirror of the eye, energy is quickly focused on the macular area, and the power of the focal point will be astonishingly large.

Laser pointers larger than 3 milliwatts can cause permanent damage to the macula of adults. Children's eye tissues are delicate and can withstand smaller amounts. A laser of about 1 milliwatt directly shot into the eyes is enough to burn a child's eyes.

How harmful are laser pointers to the eyes?

Laser pens are easy to carry, and some commercially available products have a light range of more than 50 meters, satisfying the curiosity of minors, and are therefore widely welcomed by primary and secondary school students. Laser pens in normal use are generally divided into four levels. Below level 2 (0.4 to 1 milliwatt), as long as the exposure time is not long, it will generally not cause harm to human eyes and skin; but laser pens above 3-5 milliwatts have higher power and can cause damage to the human body. At present, due to the lack of supervision, some laser pens sold around campuses have a power of up to 100 to 300 milliwatts, which can instantly ignite matches, firecrackers and paper, and even cause fires. In addition, primary and secondary school students lack the necessary self-protection awareness. When they are playing, prolonged exposure to sunlight can cause damage to the retina of the eyes and the surface of the skin, leading to permanent retinal damage and vision loss.

Depending on the degree of harm that the laser system may cause to the human body, its hazard level classification ranges from Class I lasers (no harm) to Class IV lasers such as 2000-watt carbon dioxide lasers (can cut thick steel plates). According to the EU EN-60825 standard and the relevant provisions of the General Product Safety Regulation 2005, ordinary civilian laser products can only be Class I or Class II. Class I laser products have no biological hazards, and Class II laser products have an output power of less than 1 milliwatt. Unqualified laser pens are marked as Class IIIA laser products with a power of less than 5 milliwatts. According to the hazard level classification of laser products, this type of laser product may cause blindness or other damage to the eyes under certain conditions. Obviously, laser products of this power level are not suitable for making ordinary civilian laser pens.

According to investigations by inspection and quarantine departments, laser pens currently sold on the Chinese market generally have the problem of over-power. Most products have a power between 1 and 5 milliwatts, and some are even greater than 5 milliwatts, posing a huge hidden danger to the public's vision safety. The main reason is that manufacturers, sellers and consumers generally lack safety awareness in using lasers. They only pursue the brightness of laser products but ignore the possible hazards caused by lasers. For this reason, the inspection and quarantine department reminds manufacturers of laser pens and other common civilian laser products not to ignore the dangers of product use in pursuit of product performance, but to control the power of laser products within a safe range.

After reading the detailed explanation above, do you know what will cause permanent blindness if you look at it once?

Do you already know that laser pens are beyond the "warning line" for children? I think you must know it. Today, the editor hopes that you can share with your friends what you have learned today about how harmful laser pens are to the eyes.