<unk> , also known as eyeglasses or spectacles, are vision eyewear, with clear lenses mounted in a frame that holds them in front of a person's eyes, typically utilizing a bridge over the nose and hinged arms (known as temples or temple pieces) which rest over the ears.<unk>  are typically used for vision correction, such as with reading<unk>  and<unk>  used for nearsightedness; however, without the specialized lenses, they are sometimes used for cosmetic purposes. Safety<unk>  provide eye protection against flying debris for construction workers or lab technicians; these<unk>  may have protection for the sides of the eyes as well as in the lenses. Some types of safety<unk>  are used to protect against visible and near-visible light or radiation.<unk>  are worn for eye protection in some sports, such as squash.<unk>  wearers may use a strap to prevent the<unk>  from falling off. Wearers of<unk>  that are used only part of the time may have the<unk>  attached to a cord that goes around their neck, to prevent the loss of the<unk>  and breaking. The loss of<unk>  would be detrimental to those working in these conditions. Sunglasses allow for better vision in bright daylight, and may protect one's eyes against damage from excessive levels of ultraviolet light. Typical sunglasses lenses are tinted for protection against bright light or polarized to remove glare; photochromatic<unk>  are blacked out or lightly tinted in dark or indoor conditions, but turn into sunglasses when they come in contact with ultraviolet light. Most over the counter sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be made. People with conditions that have photophobia as a primary symptom (like certain migraine disorders or Irlen syndrome) often wear sunglasses or precision tinted<unk> , even indoors and at night. Specialized<unk>  may be used for viewing specific visual information, for example 3D<unk>  for 3D films (stereoscopy). Sometimes<unk>  are worn purely for fashion or aesthetic purposes. Even with<unk>  used for vision correction, a wide range of fashions are available, using plastic, metal, wire, and other materials for frames.
Glasses
Bioactive glass
Mustard gas
Chlorofluorocarbon
Methanol
Polychlorinated naphthalene
Alkylphenol
Soylent 