The main purpose of wearing sunglasses is to block the damage of ultraviolet rays to the eyes. The corneas and crystals of our eyes are the most ocular tissues that are vulnerable to UV damage. After the eyeball is burnt by ultraviolet radiation, the eyes may have abnormal problems such as pain, dryness, tearing, foreign body sensation, redness of the eyelids, conjunctival congestion and edema, and serious eye diseases.
For example, eye diseases such as solar keratitis, cataracts, and pterygium are all related to ultraviolet rays. Ultraviolet light is divided into four bands according to wavelength: UVA, UVB, UVC and UVD. Among them, the UVC and UVD wavelengths are short and cannot reach the ground. Therefore, the UV rays we need to protect every day are only UVA and UVB. Professional sunglasses also need to be able to block UVA and UVB to protect the eyes.