???????The cornea (Cornea) and conjunctiva (Conjunctiva) of the human eye are not protected by the cuticle of the general skin, and are most vulnerable to light beams and other environmental factors. The intensity of the laser light is so high that the injury caused by the reflex action of the eyelid has a protective effect.
??????The damage to the eyes is related to the wavelength: IR-A in Visible light and Infrared affects the retina; UV-B, UV-C in Ultraviolet and IR-B, IR-C in Infrared Affect the cornea); visible light and short infrared (Near infrared; IR-A) will pass through the clear eye material and be absorbed by the retina, so if the beam is too strong, it will damage the retina. The high collimation of the laser light allows the light to converge on a very small spot, about 10 to 20 μm on the retina (thinner than the hair). Therefore, laser light between 400nm and 1400nm has a particularly high risk to the retina. This band is called the retinal hazard region (Retinal hazard region).
??????Due to the effects of heat flow and shock waves, the tissue surrounding the imaging area may also be damaged, with more serious consequences for the visual function. Because the repair ability of retinal nerve tissue is very low, this injury is generally permanent.
?????Electromagnetic waves outside the danger zone of the retina, including ultraviolet rays and long-wave infrared (Far infrared), may injure the front part of the eye. Some bands can damage the lens (Lens), and the radiation from 295nm to 320nm and 1μm to 2μm is particularly serious. Ultra-wide band ultraviolet rays and infrared rays with a wavelength greater than 1400nm may damage the cornea. When only the corneal epidermis is injured, it can be repaired within a day or two, and the vision is completely restored. If there is significant damage to the deeper parts of the cornea, corneal scars may be caused, leading to permanent blindness.
In the infrared penetration depth (Penetration depth), 1,440 nm (such as some semiconductor lasers), 1,540 nm (such as erbium-glass laser), 2,100 nm (such as holmium-Jacques laser) are all greater than 10,600 nm (carbon dioxide laser), Therefore, the risk of permanent injury caused by the first three is relatively high . The 308 nm xenon chloride (XeCl) laser beam will immediately cause cataracts in water crystals, so it also has additional dangers. Argon ion, Krypton ion, KTP double frequency, Copper vapor, Copper vapor, Gold vapor, Heliun-Neon, Nd: YAG Such lasers are potentially dangerous to the retina. Erbium-Jacques (Er: YAG), erbium-yttrium lithium fluoride (Er: YLF), holmium-Jacques (Ho: YAG), hydrogen fluoride (HF), carbon dioxide (CO2), carbon monoxide (CO) and other lasers There is danger.