Contact Lens Material

Classified by material, there are three types of contact lenses:

1. Hard lenses are made from PMMA — also known as Plexiglas or Lucite. These lenses are virtually obsolete and rarely used.

2. Soft lenses are made from gel-like, water-containing plastics, and are most common. They're a bit larger in size than your iris (the colored part of your eye).

3. GP lenses, also known as RGP or "oxygen permeable" lenses, are made from rigid, waterless plastics and are especially good for presbyopia and high astigmatism. These lenses are usually about eight millimeters in diameter, which is smaller than your iris.

From the introduction of soft lenses in 1971 until relatively recently, most lens brands have been made from "hydrogel" plastics. Recently, new silicone hydrogel contact lenses have been introduced. They have become the contact lenses of choice for many eye care practitioners, because they allow more oxygen to pass through the lens to the eye, and they are less prone to dehydration.

By, Liz Segre