Rigid Gas Permeable (RGP) Lenses: Everything You Need to Know

Rigid gas permeable lenses, also known as RGP lenses, permit oxygen to pass through them to get to the eye’s cornea.

RGP lenses must be custom fit to your eyes, and they fit more closely to the eyes than hard contact lenses.

These contacts are a good option if soft contact lenses don not improve your astigmatism. 

Intro

Rigid Gas Permeable lenses, also called RGP lenses, are rigid plastics that correct vision impairment but also allow oxygen to pass into the eye. You can use them as an alternative to eyeglasses and soft contact lenses. 

Unlike eyeglasses, you can place them directly on the eye. RGP lenses are permeable so that they can allow oxygen to get into the cornea, which needs oxygen to stay healthy.

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How Do RGP Lenses Work?

The material that makes up RGP lenses combines silicon, PMMA (polymethyl methacrylate, or Plexiglas or acrylic) and a porous plastic called fluoropolymer. Because of their rigid shape, the lenses must fit your eyes perfectly. Otherwise, they would irritate your eyes by wearing them.

Before requesting your custom design, your doctor will measure your eyes. Your unique eye shape determines the shape of the lenses.

Before the introduction of RGP lenses, people wore hard lenses. They did not allow oxygen to pass through them. Instead, they permitted tears to get in between them and the cornea.

The tears supplied oxygen to the cornea. Typically, hard lenses had to be smaller to allow tears to pass between them and the cornea.

On the other hand, RGP lenses can pass oxygen directly through the lenses. They can also do so by pumping tears inside the lens. RGP lenses are a bit larger and fit much closer to the eye than hard lenses. 

Conditions Treated

RGP lenses help to correct refractive errors, which occur when the cornea cannot focus light precisely on the retina. As a result, you may have problems like farsightedness (hyperopia), nearsightedness (myopia), and astigmatism. When you have these problems, images will appear blurry. 

RGP lenses help focus light on the retina, enabling you to see clear images. They also help prevent myopia progression by keeping the cornea in shape.

The cornea may fail to maintain its round shape. Instead, it adopts a corn shape, leading to a problem called keratoconus.

This problem is hard to correct using soft contact lenses and glasses. But RGP lenses help to reshape the cornea and restore vision. 

Corneal ectasia is an eye condition that occurs when the cornea becomes too weak after eye surgery. As a result, it starts to bulge out, leading to astigmatism. The RGP lenses help to correct this problem as well. 

Who Is an RGP Candidate?

Although RGP lenses are less used than soft lenses, they can be a perfect choice for you if:

• You have conditions like farsightedness, nearsightedness, presbyopia, astigmatism, keratoconus and corneal ectasia 
• You are willing to go through an adaptation period to achieve better vision 
• Soft lenses don not improve your astigmatism condition 

Apart from vision impairment, people wear RGP lenses for other reasons. For instance, some athletes wear them to improve their focus when playing sports. Others wear them to change the color of their eyes.   

How Are RGP Lenses Different from Soft Lenses?

RGP lenses are rigid and must be custom-made to fit your eye size. That means, they don’t change shape. On the flip side, soft contact lenses are flexible and can adapt to the shape of your eye. 

RGP Lenses Pros and Cons 

Pros

• They provide more sharp vision than soft lenses because they’re custom-made and have smooth contact with the eye
• RGP lenses allow more oxygen to pass to the eye.
• They last longer than soft lenses, making them cheaper in the long run.
• They can correct more vision impairments, including slowing down progressive myopia.
•  RGP lenses have a smooth surface that does not soak water, so they do not attract bacteria that may infect the eye.

Cons 

• They can be uncomfortable. You must wear the lenses a few hours a day until you can adapt to them.
• If you aggressively rub your eyes or participate in intensive sports, the lenses may come out due to their small size. 
• Since they don’t change shape like soft lenses, they may leave spaces for foreign materials like dust to enter underneath them.
• They are expensive to replace because a doctor must customize them for your eyes. 

Costs

RGP lenses vary in price, depending on the optometrist selling them. Some doctors include the cost of these lenses to the price of other services like eye examination. So you may want to ask for a breakdown of these fees.

RGP lens prices vary depending on durability and the evaluated visual impairment. For instance, contact lenses for astigmatism cost higher than those of nearsightedness and farsightedness. RGP lenses are more expensive than soft lenses and may cost between $75 to $325 per lens. 

FAQs 

What are RGP lenses used for? 

RGP lenses help correct visual impairment such as nearsightedness, farsightedness, and astigmatism. You can use RGP lenses as an alternative to eyeglasses and soft contact lenses. But unlike soft lenses, they’re rigid and permit oxygen to pass through them to the eye. 

Are RGP lenses the same as hard lenses? 

RGP lenses aren’t the same as hard lenses. The hard lenses are older versions that aren’t gas permeable. However, both have similar appearance and rigidity.

How long can you wear RGP lenses?

You should wear RGP lenses for at least 10 hours a day. These lenses can last for over a year if you maintain them well. You should have then checked after every six months. But you can keep using them provided they have a clear vision.

References

1. Rigid Contact Lenses. University of Illinois.

2. Ectasia After LSIK. (October 2021). American Academy of Ophthalmology.

3. Gas Permeable (GP) Contact Lenses. Hopkins Eye center.   

4. The Cost of Contact Lenses. (June 2020). Very Well Health.