The damage to the eye caused by light is mainly due to biological damage caused by temperature effects and photochemical reactions caused by the partial absorption of the light's energy by the eye -- that is, there will be damage when the energy reaches a certain amount. The predominant mode of damage depends on the wavelength of light and the exposed tissue. The harm of laser is mainly due to the tissue damage caused by high temperature caused by the absorption of light of different wavelengths by different parts, such as burns, perforations, and blood vessel ruptures.
The location of the eye injury is directly related to the wavelength of the laser radiation. Laser radiation entering the eye and its damage can be broadly classified into:
- Far ultraviolet (UVB) 280-315nm and (UVC) 100-280nm, most of the radiation is absorbed by the cornea. Ultraviolet rays can cause acute damage to the cornea and conjunctiva through photochemical action, causing protein coagulation and denaturation, resulting in shedding of the corneal epithelium. Among them, ultraviolet rays with a wavelength of 280 nanometers do the most damage to the cornea. In the early stage of the disease, people only feel a foreign body sensation and mild discomfort in both eyes. )wait. Such as repeated attacks, can cause chronic blepharitis and conjunctivitis, the formation of the so-called snow blindness and welding eye.
- Near-ultraviolet wavelength (UVA) 315-400nm, most of the radiation is absorbed by the lens of the eye, and the ultraviolet rays are absorbed by the lens after penetrating the cornea, resulting in cross-linking and coagulation of lens soluble proteins, causing the lens to age or become opaque, and eventually cataract occurs. The effects of UV light on crystals are cumulative, so the effects are delayed and may not be a problem after a few years.
- Most visible (400-760 nm) and near-infrared (760-1400 nm) radiation is transmitted to the retina, and overexposure may cause flash blindness or retinal burns and lesions. Retinopathy is based on the fact that when blood flows to the choroid layer, which is located between the retina and sclera, the thermal load on the retina cannot be regulated, and it causes thermal burns (lesions) of the eye, which burn blood vessels and cause secondary vitreous humor Bleeding, blurring vision beyond the field of vision. While minor damage to the retina can be repaired, major damage to the macular region of the retina (the area where vision is most acute) is one of the leading causes of vision or temporary or even permanent vision loss.
- Most of the radiation in the far infrared (1400 nm-1 mm) is transmitted to the cornea and overexposure to these wavelengths can cause corneal burns. Infrared rays with longer wavelengths also penetrate eye tissue and land on the retina, causing damage to the retina, especially the macula, leading to macular degeneration.