In the laser injury, the most serious injury to the eyes in the organism. Wavelength in the visible and near-infrared light laser, eye refractive medium of low absorption, high transmission rate, and refractive medium of focusing ability (i.e., focusing power) is strong. High intensity visible or near-infrared light into the eye through the human eye refractive media, light accumulation in the retina. At this time on the retina laser energy density and power density progress to thousands to tens of thousands of times, a large amount of light energy in the blink of an eye in the retina, to the retina photoreceptor cell layer temperature rises rapidly, resulting in the photoreceptor cell coagulation degeneration and necrosis and the loss of photoreceptor role. Protein coagulation and denaturation caused by overheating when the laser focuses on the photoreceptor cells is irreversible damage. Once the damage is done, permanent blindness of the eye will be formed. Different wavelengths of laser light have different levels of effect on the eye, and the results are also different. Far-infrared laser damage to the eye mainly to the cornea, this is because of this kind of wavelength of laser light is simply all absorbed by the cornea, so the cornea damage is the most serious, mainly caused by keratitis and conjunctivitis, the patient feels eye pain, foreign body-like stimulation, fear of light, tears, eye congestion, visual acuity decline. Attack far infrared light damage should be covered to maintain the injured eye, to avoid the onset of infection, symptomatic treatment. Ultraviolet laser damage to the eye is mainly cornea and lens, this band of ultraviolet laser light is simply all absorbed by the lens of the eye, and the far and middle to corneal absorption is dominant, so the lens and cornea can be caused by clouding. Laser damage to the skin:
Human skin has a very sensitive touch, pain, temperature and other functions due to the physiological structure, constituting a complete maintenance layer. And the skin consists of multiple tissue levels, in each layer there are different cells. Laser light to the skin, such as its energy (power) is too large when it can cause skin damage, of course, the damage foci can be repaired by the organization, although the function of the landing, but does not affect the overall function of the structure, and the damage to the eyes to be much lighter. However, it should be highly emphasized. Laser damage to the skin threshold is also very high, the output energy of various lasers varies greatly, and the current range of high-power lasers is very common. The level of laser damage to the skin and laser illumination dose, laser wavelength, skin color depth, tissue moisture and skin stratum corneum thickness factors related to the previous three elements for the main. Laser dose and skin damage level:
A lot of theories, reflecting the skin when the use of laser power density (or energy density) the greater, the greater the damage to the skin, the two are positively correlated ratio. After the skin absorbs the laser energy beyond the safe threshold, the skin of the irradiated parts will present thermal erythema, blisters, coagulation and thermal carbonization, boiling, quenching and thermal vaporization with the increase of the dose in turn. Thus, the mechanism of laser damage to the skin is mainly caused by the thermal effect of laser. After the skin absorbs the laser energy, part of the skin temperature rises in a short period of time, and the level of temperature rise is different, and the damage formed is also different. Especially infrared laser is prominent, such as CO2 laser (vapor laser), the skin of such 10.6μm wavelength infrared laser absorption rate is very high, the transmittance rate is very low, the skin of the CO2 laser to produce intense absorption, so that the temperature of the skin portion of the rapid increase in the formation of damage is very easy. The severity level of laser damage to the skin is determined by the skin's absorption rate of the laser, and the skin's absorption rate of the laser is determined by the wavelength of the laser. The higher the absorption rate of the skin to a certain wavelength of laser, the more serious the damage is. If the absorption rate of skin to ultraviolet laser and infrared laser is very high, these two types of lasers are the main wavelength lasers that damage the skin. Infrared laser on the skin is the main role of thermal burns, such laser illumination of the skin, the power is comparatively small and lead to capillary expansion, skin redness and heat. As the laser power density increases, the level of thermal damage also increases. On the contrary, the role of ultraviolet laser on the skin is mainly light. In the ultraviolet laser illumination of the skin can cause skin erythema, aging, excess when serious carcinogenic. Harmful to the skin of the largest ultraviolet light waves in the 270 ~ 290nm, wavelength than 270 ~ 290nm larger or smaller than the level of its harm are relatively reduced. YAG infrared laser at a wavelength of 1.064um is less harmful to the skin.