About Contact Lenses
Problems with Contact Lens
How long to wear contacts
Contact Lens for Astigmatism
Color Contact Lens
How to Choose Color contact
Bifocal and Multifocal Contact Lens
Disposable Contacts
Contact Lens for Extended Wear – Overnight Contact Lens
Contact Lens for Monovision
Gas Permeable Contact Lens
How to pick contacts
How to take care of Contact Lens
New advances in contact lens
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What are Gas Permeable Contacts?
Gas permeable contact lenses, also known as RGPs, rigid gas permeable, or oxygen permeable lenses.
Gas permeable contact lenses are rigid, but they shouldn't be confused with old-style "hard" contact lenses, which are now obsolete. Hard contact lenses were made of a material known as PMMA. Before 1971, when soft contact lenses were introduced, just about all contact lenses were made from PMMA.
The problem with PMMA lenses is that they are difficult to get used to and somewhat uncomfortable to wear. Also, PMMA does not allow oxygen to pass through it, and healthy eyes need plenty of oxygen.
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What are Gas Permeable Contact Lenses?
Gas Permeable contact lenses were first introduced in the late 1970s; they are actually a newer technology than soft lenses. Most Gas Permeable incorporate silicone, which makes them more flexible than PMMA. And silicone is oxygen permeable, so oxygen can pass through Gas Permeable lenses, resulting in greater comfort and better eye health. In fact, Gas Permeable transmit more oxygen to the eye than do traditional soft contact lenses (although some newer silicone hydrogel soft lenses are comparable to Gas Permeable in oxygen transmission).
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Gas Permeable can also provide better vision, durability, and deposit resistance than soft contact lenses. They can be easier to clean, and since they're long-lasting, they can be less expensive in the long term than soft lenses.
Benefits of Gas Permeable
Gas permeable contact lenses offer some outstanding benefits over soft lenses. For one, because an RGP is made of a stiff material, it retains its shape well when you blink, which tends to provide crisper vision than would a soft lens. |
Gas permeable contact lenses are extremely durable. Although you can break them (for instance, if you step on them), you can't tear them easily, like soft lenses. And they're made of materials that don't contain water (as soft contact lenses do), so protein and lipids from your tears do not adhere to gas permeable contact lenses as readily as they do to soft lenses. With a little care, they may last for years, as long as you don't require a prescription change.
Problems with Gas permeable Contact Lenses
Unlike soft lenses, to achieve maximum comfort with GPs, you need to wear them regularly (although not necessarily every day). If you don't wear your soft lenses for a week, they'll still be comfortable when you put them on a week later. But if you don't wear your GPs for a week, you'll probably need some time to get comfortable again.
Also, some people experience "spectacle blur" with GPs: when lenses are removed, vision is blurry, even while wearing glasses. This effect is temporary, but it can necessitate full-time GP wear. This can make GPs an all-or-nothing proposition, which some people will find inconvenient. |
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