lensesesOver 140 disposable million people contact in the United States wear lenseses. People lens whose eyes have refractive errors do not see clearly without glasses, because the light emitted from the objects they are observing does not come into focus on their retinas. for For people who are farsighted, images come into astigmatism and disposable focus behind the retina; contact for people who are nearsighted, images lens come into focus in front of the retina. Lenses for and astigmatism work by changing disposable the direction of light so that images come into focus on the retina. The greater contact the index of refraction of the lens material and the greater the difference in the curvature lens between the two surfaces of the lens, the greater the for change in direction of light that passes through it, and the greater the correction.Lenses can be unifocal, with one correction for all distances, or astigmatism they can be correct for more than one distance (multifocal). One type disposable and contact of multifocal, the bifocal, has an lens area of the lens (usually at the bottom) that corrects for nearby objects (about 14 in from for the eyes); the remainder of the lens corrects for astigmatism and disposable distant objects (about 20 ft from the eyes).

Preschool contact and lens and school-age for childrencontact are a significant improvement astigmatism over lenseses for children and adolescents who participate in sports or outdoor disposable and contact and lens activities.contact for are recommended astigmatism for most athletes who disposable need corrective eyewear. Often, a single pair of lenses is less expensive than the combined cost contact and lens and for of glasses and prescription goggles. Swimmers especially can benefit astigmatism and disposable from contact being able to see underwater lens while wearing regular goggles over their contact. Because contact tend to dry the eye, swimmers and all athletes should take care to blink several for and astigmatism and disposable times before contact and after an activity session in order to assure natural cleansing. If any pool water enters a swimmer''s eyes, the lenses should be thoroughly disinfected lens as soon as possible to remove pool contaminants. for Children who like spending time looking into a telescope, microscope, or binoculars may also prefer contacts over lenseses astigmatism.