Kinds of Optical Lenses for Distance & Reading

An individual with reading induced headaches, or difficulty reading street signs while driving, likely has some sort of vision problem and needs optical lenses. Single lens glasses help people with either near-sightedness or far-sightedness, while biofocal and other multifocal lenses help individuals in need of multiple prescriptions for multiple degrees of vision problems. Some individuals need other optical lens correction, like prism and UV protection, as well.

Concave and Convex

• Near-sightedness, a condition where a person's vision focuses in front of an abnormally long eye, causes problems with distance sight. A concave lens corrects this problem by bending light rays outward, pushing the focal point back into the eye. Far-sightedness, a condition where vision focuses behind an abnormally shortened eye, causes a problem with reading and close range sight. A convex lens fixes this problem by bending light rays inward and drawing the focal point further into the eye.

Single Vision and Multifocal Lenses

• Single focus lenses have a single prescription and address a single eyesight problem, either near-sightedness or far-sightedness. Multifocal lenses, most commonly referring to bifocals and trifocals, have several prescriptions within a single lens, which addresses multiple vision problems by adjusting the focal point through the use of those various prescriptions. Standard multifocal lenses have a distinct line separating the various prescriptions, but progressive lenses gradually blend their multifocal sections together, thereby removing the visible segment lines.

Prism

• Some individuals have one near-sighted eye and one far-sighted eye, causing double-vision, one of many conditions where the eyes pull apart during use and no longer work together. For these individuals and others whose eyes have similar muscular imbalances, an optometrist often prescribes a lens with prism. The prism bends light rays in such a way that the eyes strain less and the two images align into one, causing the brain to think that the eyes work together.

Light Protection

• All eyes need protection from the sun's ultraviolet rays, but for individuals already wearing corrective lenses in the form of glasses, rather than contacts, standard sunglasses work ineffectively. These individuals usually need polarized clip-on sunglasses that attach to their regular lenses or polarized sunglasses specially made with their prescriptions. Moreover, polarized lenses block UVA and UVB rays, reducing glare, while sunglasses with regular lenses only decrease light intensity.

  Transition lenses provide an alternative option for individuals with corrective lens glasses. These lenses darken when exposed to UV light and turn clear when indoors, protecting the eyes from sunlight-induced harm.