Rigid Gas Permeable Contact Lenses
Rigid Gas Permeable (RGP) contact lenses are smaller than soft lenses. They are often called “hard” lenses, but this is not to be confused with the actual hard lenses that were made of a hard plastic many years ago. The older hard lenses did not allow air to pass through the lens, which could damage the cornea over time. Rigid Gas Permeable lenses do allow gas (in this case oxygen) to pass through the lens. Although these lenses are harder then soft lenses, they are not considered true hard lenses.
What types of prescriptions can use these lenses?
Near-sighted, far-sighted, and those with astigmatism can use RGP lenses. Those who need bifocals can try multifocal RGP lenses.
How does it work?
The rigid surface of the lens creates a basin for tears to fill in between the back surface of the lens and the front surface of your eye. Although there is power in the lens to correct your vision, many times the tears that fill in the gap between the lens and your eye can help correct your vision. Because the tears can fill in any gap, they correct irregularities in the corneal surface. Many people feel that they see clearer with RGP lenses versus soft lenses, but it does depend a lot on the fit of the lens.
How are they used?
RGP lenses can be used for almost any contact lens wearer. They are custom made to your prescription and eye shape, which is a big advantage on unusually shaped corneas or those with a lot of astigmatism. But they work very well on almost anybody. RGP lenses are not replaced as often as soft contact lenses. Some wearers are able to use the same pair of lenses for many years. Eventually the lenses become scratched or warped from cleaning them so much over time. Many people like RGP lenses because of the reduced cost over time since they do not have to be replaced as often.
How do they handle?
Because they are smaller diameter, they are easier for some people to insert into their eye.They can also be made into various handling tints, which make the lenses easier for some people to find when getting ready to put them in.
One disadvantage is that they lenses can break if stepped on, but they do not usually break routinely. Because they are made of a rigid plastic, you may have some initial lens awareness when you first start wearing them. This can be improved as your doctor makes lens design changes during your fitting process.
Cost over time is less than with soft contact lenses. They have a smaller diameter and are easier to handle. They are custom made for each individual, versus soft lenses which are pre-made by molds that come in a limited set of parameters.