Contact Lens Materials

What your contact lenses are made of affects how they wear in many senses of the word, including how long they last, your comfort and their health impact. For many years contact lenses were made of glass. Today, fewer than 1% are, with the other 99% made from various types of plastic. The choices are predominantly some type of PMMA (polymethyl methacrylate), polycarbonate or silicon hydroxy gel.

Hard contact lenses introduced in the 1960s are made of PMMA and don’t allow oxygen to move directly through the lens, but some air does reach under it anyway. When a person blinks the lens moves slightly and some air diffuses through the tear solution that covers the eyeball.

Soft contact lenses, first introduced in 1971, were made of a polyacrylamide containing nitrogen (hydroxyethyl methacrylate or HEMA) which made them what is called ‘hydrophilic’. This ability to absorb water makes them flexible, and therefore more comfortable. At the same time, they are slightly more permeable to air than their older cousins.

RGP (Rigid Gas Permeable) lenses are midway between a truly hard lens, like glass or PMMA, and a soft lens. They combine PMMA with silicone and fluoropolymers that allow air to get to the eye. That increases your comfort and reduces the odds of health problems due to long-term wear.