Description

Glasses, also known as eyeglassesorspectacles, are devices consisting of glass or hard plasticlensesmounted in a frame that holds them in front of a person'seyes,typically using a bridge over the nose and arms which restover theears. Glasses are typically used for vision correction,such aswith reading glasses and glasses used for nearsightedness.Safetyglasses provide eye protection against flying debrisforconstruction workers or lab technicians; these glasses mayhaveprotection for the sides of the eyes as well as in the lenses.Sometypes of safety glasses are used to protect against visibleandnear-visible light or radiation. Glasses are worn foreyeprotection in some sports, such as squash. Glasses wearers mayusea strap to prevent the glasses from falling off during movementorsports. Wearers of glasses that are used only part of the timemayhave the glasses attached to a cord that goes around their neck,toprevent the loss of the glasses.

Sunglasses allow better vision in bright daylight, and mayprotectone's eyes against damage from high levels of ultravioletlight.Typical sunglasses are darkened for protection against brightlightor glare; some specialized glasses are clear in dark orindoorconditions, but turn into sunglasses when in bright light.Mostsunglasses do not have corrective power in the lenses;however,special prescription sunglasses can be ordered. Specializedglassesmay be used for viewing specific visual information (suchasstereoscopy) or 3D glasses for viewing three-dimensionalmovies.Sometimes glasses with no corrective power in the lenses arewornsimply for aesthetic or fashion purposes. Even with glassesusedfor vision correction, a wide range of designs are availableforfashion purposes, using plastic, wire, and othermaterials.