Vision care
Eyewear is used for either protective, prosthetic or aesthetic purposes. Eyeglasses are provided with lenses that serve a purpose, such as correcting a wearer's vision, filtering sunlight, or preventing airborne objects from impacting the wearer's eyes. Eyeglasses, also commonly known as spectacles or glasses, comprise an instrument or device including lenses or prisms mounted in a plastic or metal frame to hold them in position in front of the eyes, for the purpose of aiding vision or compensating for various visual defects such as myopia or astigmatism for example. Often the lens may serve more than one of these functions, such as both filtering sunlight and providing impact protection, for example. Eyeglasses are roughly classified into two types, namely, those mounting thereon lenses for correcting eyesight and those mounting lenses for cutting out ultraviolet (so-called sunglasses). In addition to correcting visual defects, eyeglasses are also commonly worn to protect the user's eyes from harm caused by environmental or workplace hazards. The most common form of eyeglasses consists of a pair of glass or plastic lenses mounted within a metal or plastic frame resting the bridge of the nose that is and usually supported by a pair of nose pads for a nose piece shaped to provide a comfortable fit. While glasses are successful in correcting many vision problems, they are easily damaged, require repeated cleaning, tend to change the appearance of the wearer and are somewhat heavy and uncomfortable. The use of contact lenses to improve the optical properties of the eye and for reasons of appearance is continuously becoming more popular. Contact lenses have minimal mass and size, are easy to use, do not substantially change the user's appearance, and can correct vision problems without reducing field of vision. Contact lenses are generally used to correct various types of vision problems. Contact lenses may include either or both spherical correction or cylinder correction depending on the particular circumstances of the lens wearer's eyes. Generally, contact lenses include hard lenses formed from materials prepared by polymerization of acrylic esters, such as polymethyl methacrylate (PMMA); rigid gas permeable (RGP) lenses formed from silicone acrylates and fluorosilicone methacrylates; and gel, hydrogel or soft type lenses. Contact lenses having one or more colorants dispersed in the lens or printed on the lens are in high demand. Bifocal contact lenses generally are classified into two types, segmented and concentric. Segmented bifocal contact lenses have two or more vertically separated power zones. Concentric bifocal contact lenses have two or more annular power zones. Sunglasses, which suppress glare, may be made with films having moderate neutral polarizing efficiency. Sunglasses, which selectively filter transmitted light, may be made with multilayer thin-films, diffractive structures that selectively reflect light or dyes with chromatic absorption. The human eye is a sensitive organ. Because of its sensitivity and its constant exposure to the environment during every person's routine daily activities, the eye is perhaps more susceptible to irritation and injury than any other human organ. Safety eyewear products in the form of eye shields, goggles, facemasks and helmets with eye shields are well known and are effective for their protective purposes. Safety eyeglasses differ from ordinary eyeglasses in that the lenses must effectively resist being dislodged from the rim in the event that a shock or impact force is applied onto the front surface of the eyeglass lenses. Protective eyewear is available in the market place for both safety and recreational applications. Protective eyewear for use in industrial settings and for use in sports activities typically takes the form of eyeglasses and goggles. Eyeglasses include earpieces or temples extending rearward from the lenses to engage the sides of the user's head. Goggles include an elastic band connected at each end to the sides of the lenses and which will extend about the user's head.
Vision care categories
Contact lenses
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