What are Rigid Gas Permeable Contact Lenses (RGP)?
Gas permeable contact lenses (GP) or rigid gas permeable contacts (RGP) are hard contacts. They’re made of a firm plastic material that allows oxygen to pass through to the eye (oxygen-permeable lenses).
Old-fashioned hard contacts were made of polymethyl methacrylate (PMMA). One drawback of PMMA is that it doesn’t let much oxygen pass through.
Now, GP lenses incorporate silicone, which allows more oxygen to reach your eyes. Newer gas permeable lenses are much healthier for your eyes than older models of hard contacts.
Though still not as popular as soft lenses, rigid lenses offer many advantages to the modern contact lens wearer. Your eye care practitioner can determine which type of contact lens is suitable for you.
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Benefits of Gas Permeable Contact Lenses
Advantages of GP lenses include:
Breathability
Several factors make GP lenses more breathable:
- Permeable lens materials. The silicone in GP lenses provides more oxygen flow to your eyes. This reduces the risk of eye problems related to a low oxygen supply. However, newer soft lens materials with silicone hydrogel are comparable.
- Smaller diameter. GP lenses are smaller than soft contacts. This means they cover less surface area, which allows more oxygen to reach the eye.
- Rigidity. GP lenses maintain their shape, which allows them to move on your eye with every blink. When they do, fresh tears and oxygen move beneath the lens. Soft lenses conform to the shape of your cornea, allowing minimal movement.
Highly Customizable
GP contacts are customized to fit your eye shape and prescription. Your eye doctor specifies the lens’s power, diameter, curvature, tint, and other features.
This makes GP contacts an alternative for people who can’t wear soft lenses due to their eye shape. For example, if your corneal shape is irregular due to keratoconus, rigid contact lenses may be right for you.
Sharper Vision
Rigid materials provide a consistent, smooth surface. This 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. This can cause blurry and fluctuating vision.
Suitable for High Prescriptions and Astigmatism
GPs can correct many prescriptions, including very high astigmatism and presbyopia.
Durability
Because of the durable, rigid material, GP contacts can last a year or more with proper care. Unlike soft lenses, GP contacts don’t rip or tear.
Cost Effective
Because GPs 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.
Resist Buildup
Because of their smooth surface, GP lenses don’t absorb water. This makes them less prone to deposit buildup. Additionally, GP lenses are less likely to attract bacteria that may cause eye infections.
Limitations of Gas Permeable Contact Lenses
Rigid gas permeable lenses also have some disadvantages, including:
Adaptation Period
Many people choose soft contacts because they’re much more comfortable the first time you put them on. Because of the hard material, GP lenses require a period of adaptation to get used to. This can take a few weeks or more.
Soft lenses may be a better choice if you’re looking to use contacts occasionally. With soft contacts, you don’t have to worry about the adaptation period.
Increased Risk of Falling Out
Gas permeable contact lenses are smaller than soft contacts. This means they have a higher chance of falling out during contact sports or if you rub your eye too hard.
Susceptible to Dust
Because rigid lenses don’t conform to the shape of your eye, dust, and foreign objects are more likely to get trapped underneath the lens. You must be careful around dust, sand, and other irritants.
More Costly to Replace
Though GP contacts can be more cost-effective long-term, replacing a lost or damaged lens is more expensive. And because they’re custom-made, it can take up to a week to get a replacement.
It’s a good idea to purchase a backup pair of GP lenses to avoid this inconvenience.
Who is a Good Candidate for Gas Permeable Lenses?
Because gas permeable lenses are customizable, they can correct a range of refractive errors, including:
- Myopia (nearsightedness)
- Hyperopia (farsightedness)
- Presbyopia (age-related farsightedness)
- Astigmatism
Other conditions where RGP lenses may be beneficial include:
Keratoconus
Keratoconus is an eye disease where your cornea thins out and develops a cone-like shape.
As a result, glasses and soft contacts often don’t provide sufficient vision correction. Many people with keratoconus use GP contact lenses.
Corneal Ectasia
Corneal ectasia is a rare complication of laser eye surgery where your cornea is too thin.
Like keratoconus, people with corneal ectasia may develop irregular astigmatism. Glasses may not correct your vision completely. GPs can improve the quality of vision significantly.
Progression of Myopia
Myopia progression occurs when nearsighted correction increases steadily throughout childhood. Many parents are concerned with their children being highly nearsighted.
One way to temporarily reduce nearsightedness and slow myopia progression is with a GP lens called orthokeratology (ortho-k) lens. They’re worn while sleeping and temporarily flatten the cornea to provide some vision correction during the day.
Hybrid Contact Lenses
Hybrid contacts combine the optical clarity of a GP lens with the comfort of soft lenses. Hybrid lenses have a center of gas permeable material surrounded by an outer ring of soft lens material.
This type of specialty contact lens is considered the best of both worlds. Hybrid lenses were created to overcome discomfort, the primary barrier preventing many people from using GP lenses.
How Much Do Gas Permeable Contact Lenses Cost?
Rigid gas permeable contact lenses cost about $35 to $95 per lens. A yearly supply costs around $70 to $190 for a pair if you replace them annually.
Factors that may affect the cost include:
- Bifocal or multifocal lenses typically cost more than single vision
- Eye doctors usually charge more for GP lens fittings because they’re personalized
- Your insurance plan may cover some or all of the exam and lens costs
- Some contact lens retailers may offer lower prices
Summary
Gas permeable (GP) or rigid gas permeable (RGP) contact lenses offer many benefits compared to soft lenses. They also have some limitations.
GP lenses are made of durable plastic that allows more oxygen and moisture to reach your eyes. This offers clearer vision and a lower risk of eye infections.
Compared to soft lenses, GP contacts take more time to get used to. Hybrid contacts may be an option for people who could benefit from GP lenses but find them uncomfortable.
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