Rigid Gas Permeable : RGP
Gas permeable (GP) contact lenses are also known as rigid gas permeables (RGP’s). Although today’s gas permeable lenses are made of a rigid material that is not flexible, they differ greatly from the original hard lenses of yesteryear. Hard contact lenses made of polymethylmethacrylate (PMMA), were introduced in the 1930’s. Considered innovative and technologically advanced for the time, these hard lenses were nearly rendered obsolete by soft lenses that debuted in the early 70’s.
A decade later, rigid gas permeable lenses appeared on the scene. For clarification, vision specialists refer to these contacts by several names: gas permeable (GP) or Rigid Gas Permeables (RGP’s). RGP’s are constructed of flourosilicone acrylate.
There are several reasons why RGP’s may be the right choice for some patients, including:
- Eye health
- Ability to diffuse oxygen (unlike hard lenses)
- Less likely to transmit infection
- Easily cleaned
- Unlike soft lenses RGP’s retain shape and do not dehydrate
- Long lasting
- Clearer vision
- Custom made for each patient
- Adaptability
- Affordability
It is easy for people with healthy eyes to take vision for granted, but the human eye is a remarkable organ. The makeup of the human eye and the series of natural occurrences within it, that allow a human being to see clearly, is at the very least, astounding. For instance, the cornea’s surface is clear and contains absolutely no blood vessels. It is unlike any other tissue in the human body that utilizes blood vessels for nourishment and protection. Gas permeable contact lenses, allow oxygen to flow to the eye and assist the cornea in defending the eye from infection and disease; protecting overall eye health.
Gas permeable contact lenses promote eye health
The overall health of the cornea is extremely important. The cornea or the window of the eye, in a combined effort with the sclera (white part of the eye), lashes and tears protect the internal eye from debris and germs. The five layers of the cornea must remain clear without any opacity. Oxygen is essential in the process and is necessary to keep the cornea healthy so that it may in turn, protect the rest of the eye.
The surface of a gas permeable lens is more resistant to deposits than soft lenses. In contrast, rigid gas permeable lenses are less sponge-like and will not soak up substances that can house bacteria. GP lenses are more durable than soft lenses and because they are obviously harder, they retain better shape.Gas permeable contact lenses play an important role, allowing the proper interaction of the eye with oxygen from the air. The cornea draws oxygen from the air as tears act as a dissolving agent. The tears dissolve the oxygen from the air and transport it through the cornea, mimicking the job of blood vessels in other parts of the body. A second gas, carbon dioxide, is a byproduct of the process and is eliminated by the cornea. Interruption of this complex process makes the eye vulnerable to maladies such as corneal scarring, loss of transparency, blood vessels, and corneal warping.
Initially, gas permeable lenses take a little more getting used to than soft lenses. Within a short amount of time, however, the eyes become accustomed to wearing rigid lenses. Whereas the adaptability to soft lenses is almost immediate, it could take up to a week or two before patients find gas permeables as comfortable.