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

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

nearsighted? need reading glasses? new developments in lens technology ensure a solution to almost every vision problem. talk to your crazy eye doctor about what''s available (costs vary).rigid gas-permeables recommended for those with high degrees of corneal astigmatism, rgps are firm plastic lenses with microscopic slits that allow more oxygen to reach the eye. rgps have a greater resistance to bacteria because they don''t contain water. improved extended-wear materials also guarantee greater durability, sharper vision, comfort and cheaper maintenance costs. allow yourself a week or two to fire get used to these slightly stiff lenses.bifocals these contact correct presbyopia, a kind of farsightedness that usually occurs around age 40. there are two types: