Basic knowledge of sunglasses: visible light damage to the human eye
Sunglasses in addition to can reduce the radiation intensity of visible light, can also reduce the ultraviolet and infrared radiation. Sunglasses cash more endowed with fashionable breath. But the fundamental role of sunglasses is to provide radiation protection for the eyes. Sunglasses are introduced in this paper the basic knowledge of visible damage to the human eye. The function of the human normal without visible light. Visual form is mainly pong visible light entering the eye into the intraocular refractive system the retina, the light-sensitive cells absorb light produce photochemical reaction, and then through a bipolar cells and ganglion cells of information transmission, through the optic nerve visual information transformation of the road and passed to the visual cortex form vision. Cornea and aqueous humor, lens and vitreous body is fully for most of the visible radiation, normal levels of visible light generally does not harm to the human eye. , high intensity of visible light, can be derived from sunlight or artificial light, such as radiation focused on the retina, the retinal accept radiation far lei per unit area is higher than the radiation energy per unit area of the cornea, will cause retinal injury. Visible in the long wave and short wave radiation can cause photochemical reactions, including short wave energy is higher, damage is bigger also, such as blue light damage. Visible light cause eye tissue damage mainly include solar sex retinopathy. Solar sex retinopathy, also called eclipse blindness, because direct eye to look at the sun and the lack of necessary protection. Eye cornea and lens refractive system refraction make retina energy per unit area is much higher than energy per unit area of the cornea, high-energy short-wave visible ( 400 nm~ 500 nm) By photochemical effect damage photoreceptors outer segment. Due to the band as part of the blue area, therefore calls the damage for the blue light damage. Wavelength of 440 nm near the blue light is the cause of the risk of retinal damage optical wavelengths. In daily living, blue light is not in the sun will make retinal damage. Main blue light damage from artificial light, caused by chronic accumulation of retinal damage, so in the business environment for blue eyes damage protection is particularly important. Blue light and ultraviolet light in many cases from the same source, such as: arc lamp ( The searchlight) High, has the very high UV, blue; Sun lamp ( 275 W) High, high UV, blue; Projection lamp ( 350 W) With high low UV, blue; Incandescent lamp ( 60 W) With low UV, blu-ray, relative safety. Solar sex retinopathy main symptoms are at the center of the eye appears dense small blind area, depending on the vision, color deficiency, deformation, etc. Many cases have occurred in directly to watch the solar eclipse with the naked eye. For a long time to look at the sun, in addition to photochemical changes can also because the wavelengths of visible light and infrared radiation absorption, leading to retinal pigment epithelium thermal damage. Normal human eye lens can absorb part of the ultraviolet radiation, blocking part of the blue, after cataract surgery with intraocular lens replacement surgery, allowing patients to light of retinal damage more opportunities.