Lasers are something that we all come into contact with in our daily lives, such as laser beams at night, laser pens, etc. So what is a laser? Many people are not sure. LASER is an acronym for “Light Amplification by Stimulated Emission”, a light source invented artificially in the 1960s. Laser has high coherence, high directionality and high brightness. Because of the laser’s good collimation characteristics and the human eye’s sensitivity to green light, people can see the beautiful column of light from the green laser pointer in a dark environment and where it points. When it comes to laser damage to the human body, mainly eye damage is the most serious. The human eye is like a very sophisticated camera on the human body, the human body from the outside world to get 70% of the information from the eyes. Laser damage to the eye can be done to all parts of the eye. The wavelength of the laser varies, as does the degree of its effect on the eye and the consequences. One of the most serious consequences is permanent blindness. Lasers with wavelengths in the far-infrared range can cause damage to the eye primarily to the cornea. Because almost all laser light of this wavelength is absorbed by the cornea, the corneal damage is the heaviest, and patients often feel foreign body-like irritation in their eyes, fear of light, tearing, and loss of vision. At this time, the injured eye should be protected from infection and treated symptomatically. Laser light with wavelengths in the ultraviolet range can cause damage to the cornea and lens. This is because the lens strongly absorbs laser light in that wavelength range. If the radiation is received excessively, it can lead to cataracts. If absorbed by the cornea and conjunctiva, it can lead to keratitis, corneal epithelial detachment and conjunctivitis, such as electrophthalmia, which may also produce effects similar to snow blindness. Laser light with wavelengths in the visible and near-infrared light range has low absorption and high transmission in the refractive medium of the eye, while the focusing ability (i.e., focusing power) of the refractive medium is strong. Intensity of visible light or near-infrared light into the eye can pass through the refractive medium of the human eye and accumulate on the retina. At this time, the laser energy density and power density on the retina will increase to thousands or even tens of thousands of times, a large amount of light energy in the retina in an instant, resulting in a rapid increase in the temperature of the retinal photoreceptor cell layer, so that the photoreceptor cell coagulation, degeneration, necrosis and loss of light-sensitive role. The coagulation and degeneration of proteins caused by the overheating of laser light on the photoreceptor cells is irreversible damage, and if the focus is on the macula of the retina, the macula will be burned and cause blindness. The laser treatment we use for the treatment of fundus disease takes advantage of this characteristic of the laser. In the treatment, the laser used for macular disease is a special wavelength laser with a very low energy value of less than 100 mJ and an irradiation time of less than 0.1 second, and it also avoids the central concave of the macula and irradiates only the peripheral area. When the retina is damaged by laser, it can show congestion, edema and hemorrhage, resulting in vision loss and blurred vision; if the laser is focused on the macula directly, because the macula is non-renewable, once it is burned, it cannot be recovered, and it will lose fine vision, appear dark area and deformation in the central part of the visual field, although the macula will not be completely blind, but it will cause serious vision problems, which will have serious impact on future life and work. Although macular damage will not cause complete blindness, it will cause serious vision problems and will have serious impact on future life and work. In our daily life, the laser device we are most exposed to is the laser pointer. Although the laser pointer looks small and has low power, it can cause serious damage to human eyes. Scientists once tested a 0.5 milliwatt laser on the human eye and compared it with the energy of sunlight and found that the laser irradiated the retina 80 times more than sunlight. Such a large irradiance will, of course, cause retinal burns. Examples of blurred vision caused by direct laser pointer radiation on the eye and diagnosed with retinal damage and disruption of macular continuity are common. As you can see, shooting a laser pointer directly into the eye will have serious consequences. In the use of laser pointer must pay attention to the following issues: first, must strictly comply with the safety rules of operation. Such as handheld laser pointer work, the staff must not laser pointer directly into the eyes of people, if there are laser toys, children must be informed that they can not shoot directly into the human eye. Second, if needed should be equipped with laser protective goggles. Protective glasses can block most of the laser beam. Again, regular health checks should be conducted. Long-term exposure to the laser pointer staff should be regularly checked the fundus of the eye, in time to do a good job of protection.