Rigid Gas Permeable Contact Lenses

What Are Rigid Gas Permeable Contact Lenses (RGP)?

Rigid gas permeable (RGP) lenses are hard contact lenses, which are also known as GP (gas permeable) lenses or oxygen permeable lenses. 

The first plastic contact lenses were produced in the 1930s. They consisted of a material called polymethyl methacrylate (PMMA). One drawback of PMMA is that it does not allow much oxygen to pass through the lenses. 

Modern RGP lenses incorporate silicone, which allows more oxygen to reach your eyes. These lenses are much healthier for your eyes than older models of hard lenses.

How Do RGP Lenses Work?

RGPs are customizable lenses that correct refractive errors, including myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. They also correct presbyopia (age-related farsightedness). 

RGP lenses work by creating a smooth surface over your cornea (clear tissue covering the front of the eye), while your tears fill in the space between the lens and your eye. This surface allows you to see clearly and maintain sharp vision throughout the day. Each time you blink, the lens moves, allowing tears to circulate underneath the lens.

Other conditions where RGP lenses may be beneficial include:

• Keratoconus is an eye disease where the cornea (the clear tissue covering the eye) thins out and develops a cone-like shape. As a result of this corneal distortion, glasses and soft contacts often do not provide sufficient vision correction, so many keratoconus patients use RGP contact lenses.
• Corneal ectasia, a type of corneal thinning, is a rare complication of laser eye surgery. Like keratoconus, people with corneal ectasia may develop irregular astigmatism and find that eyeglasses do not adequately correct the vision. RGPs can improve the quality of vision significantly.
• Myopia progression occurs when the nearsighted correctionincreases steadily throughout childhood. Many parents are concerned with their children being highly nearsighted. One way to temporarily reduce nearsightedness and potentially slow myopia progression is with a type of RGP lens called orthokeratology (ortho-k) lens. They are worn while sleeping and temporarily flatten the cornea to provide some vision correction during the day.

Soft Contact Lenses vs. Rigid Gas Permeable Lenses

Although most people wear soft contact lenses, there are benefits to both soft and rigid contact lenses. Your eye doctor can determine which type of contact lens is suitable for you. 

Pros of RGP Contact Lenses 

Here are some benefits of RGP lenses:

• Sharper vision. The lens is rigid, which provides a consistent, smooth surface. This feature allows you to have clear vision all day. Soft contact lenses may change shape throughout the day as you blink and as the lenses dry out, which causes blurry and fluctuating vision.
• Suitable for high prescriptions. Some people prefer RGPs because they are not satisfied with their vision in soft contacts. These are often people with high prescriptions, particularly high astigmatism. Soft contacts are also limited in the prescription strengths they can correct. RGPs can correct a wider range of prescriptions.
• Highly customizable. Depending on your eye shape and prescription, your eye doctor specifies the power, diameter, curvature, tint, and other features of the RGP. The lens is custom made and sent back to your doctor. Once the doctor fits the RGP on your eye, they can determine if adjustments need to be made. 
• Durable. Most soft contact lenses only last a month or less. Because of the durable, rigid material, RGPs typically last a year or more with proper care. They do not tear like soft contact lenses, although they can scratch, chip, or crack if not handled properly.
• Cost-effective. Because RGPs last longer, they often cost less than soft contacts, which must be replaced frequently. However, they are more expensive to replace if you lose or break a lens.
• Avoid dehydration. Soft contact lenses tend to dry out on the eyes, causing discomfort and blurred vision. RGPs avoid these issues because the lenses do not dehydrate.
• Correct presbyopia. Bifocal and multifocal RGPs are available to correct your vision if you wear reading glasses.

Cons of RGP Contact Lenses

These are some disadvantages of RGP lenses:

• Initial discomfort. Many people choose soft contact lenses because they are much more comfortable the first time you put them on. Because of the hard material, RGPs cause more discomfort initially.
• Longer adaptation. RGPs take longer to adapt to, sometimes a few weeks or more. If you are looking to use contacts occasionally, soft contact lenses may be a better choice. With soft lenses, you do not have to worry about the adaptation period. RGPs are more suitable for those who plan on wearing contacts daily.
• Smaller size. RGPs are quite a bit smaller than soft contact lenses and have a higher risk of falling out of your eye. Eye rubbing or physical activities can make the lens more likely to dislodge. 
• Susceptible to contaminants. Because RGPs do not conform to the shape of your eye like soft contacts, foreign objects are more likely to get trapped underneath the lens. Exercise precaution when you are exposed to dust, sand, and other irritants. 

FAQs - Common Questions and Concerns

Here are some frequently asked questions about rigid gas permeable lenses: