Glasses, also known as eyeglasses or spectacles, are devices consisting of glass or hard plastic lenses mounted in a frame that holds them in front of a person's eyes, typically using a bridge over the nose and arms which rest over the ears.
Glasses are typically used for vision correction, such as with reading glasses and glasses used for nearsightedness.
Safety glasses provide eye protection against flying debris for construction workers or lab technicians; these glasses may have protection for the sides of the eyes as well as in the lenses. Some types of safety glasses are used to protect against visible and near-visible light or radiation. Glasses are worn for eye protection in some sports, such as squash.
Glasses wearers may use a strap to prevent the glasses from falling off during movement or sports. Wearers of glasses that are used only part of the time may have the glasses attached to a cord that goes around their neck, to prevent the loss of the glasses and breaking.
Sunglasses allow better vision in bright daylight, and may protect one's eyes against damage from high levels of ultraviolet light. Typical sunglasses are darkened for protection against bright light or glare; some specialized glasses are clear in dark or indoor conditions, but turn into sunglasses when in bright light. Most sunglasses do not have corrective power in the lenses; however, special prescription sunglasses can be ordered.
Specialized glasses may be used for viewing specific visual information, for example 3D glasses for 3D films (stereoscopy). Sometimes glasses are worn purely for fashion or aesthetic purposes. Even with glasses used for vision correction, a wide range of fashions are available, using plastic, wire, and other materials.
People are more likely to need glasses the older they get with 93% of people between the age of 65-75 wearing corrective lenses.
A contact lens, or simply contacts, is a thin lens placed directly on the surface of the eye. Contact lenses are considered medical devices and can be worn to correct vision, or for cosmetic or therapeutic reasons. In 2004, it was estimated that 125 million people worldwide use contact lenses, including 28 to 38 million in the United States. In 2010, the worldwide market for contact lenses was estimated at $6.1 billion, while the US soft lens market was estimated at $2.1 billion. Multiple analysts estimated that the global market for contact lenses would reach $11.7 billion by 2015. As of 2010, the average age of contact lens wearers globally was 31 years old, and two-thirds of wearers were female.
People choose to wear contact lenses for many reasons. Aesthetics and cosmetics are the main motivating factors for people who want to avoid wearing glasses or to change the appearance of their eyes. Others wear contact lenses for functional or optical reasons. When compared with spectacles, contact lenses typically provide better peripheral vision, and do not collect moisture (from rain, snow, condensation etc.) or perspiration. This can make them preferable for sports and other outdoor activities. Contact lens wearers can also wear sunglasses, goggles, or other eyewear of their choice without having to fit them with prescription lenses or worry about compatibility with glasses. Additionally, there are conditions such as keratoconus and aniseikonia that are typically corrected better with contact lenses than with glasses.
The size of the contact lens market is likely to grow due to the increasing occurrence of eye-related conditions such as astigmatism, hyperopia and myopia. The other drivers are increasing population, the desire to make fashion statements, and technological advancement. By the end of 2020, the value of the contact lens market is predicted to reach $13.5 billion.