NEARSIGHTED? NEED READING GLASSES? New developments in lens technology ensure a solution to almost every vision problem. Talk to your 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 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:

Originally, hard contact were made of a material called PMMA. Although still available, the more common types of contact are listed below:Rigid gas-permeable (RGP) daily-wear lenses are made of plastic that does not absorb water but allows oxygen to get from the atmosphere to the cornea. (This is important because the cornea has no blood supply and needs to get its oxygen from the atmosphere through the film of tears that moves beneath the lens.) They must be removed and cleaned each night. Rigid gas-permeable (RGP) extended-wear lenses are made from plastic that also does not absorb water but is more permeable to oxygen than the plastic used for daily-wear lenses.

contact The concept of corrective lenses that sit directly on the eyeball was developed in the ninth century, but it was not until the late 20th century that manufacturing and grinding techniques for contact were perfected. Originally contact were made of glass, then later of hard plastic, and still later of flexible, highly oxygen-permeable soft plastic. Today, the majority of lenses worn are of two basic types: rigid gas permeable (so-called "hard" lenses) and lenses. best lenses are smaller and more durable, but require a longer period of adjustment for the wearer. Hard contact can correct some vision problems, like astigmatism, that the lenses cannot. The lenses are slightly larger than best lenses. They are more comfortable and less expensive, but can be easily torn. The latest generations of contact are extended and disposable lenses. extended lenses are intended to be worn for several weeks at a time, while disposable lenses are thrown away every day or every few weeks, or in the newest versions, every day.