Gas Permeable Contact Lenses

Last updated on June 8th, 2017 at 06:59 pm

Gas permeable contact lenses are stiff lenses made from long lasting plastic that transmits oxygen. These lenses likewise are called GP lenses, stiff gas permeable lenses, RGP lenses and oxygen permeable lenses.

GP contact lenses are rigid, however they shouldn’t be confused with old-fashioned difficult contact lenses, which are now essentially outdated. Tough contact lenses were made from a type of plastic called poly methyl methacrylate (PMMA). Prior to 1971, when soft contact lenses were introduced, practically all contact lenses were made from PMMA, which is also called acrylic or acrylic glass, as well being described by the trade names Plexiglas, Lucite, Perspex and others.

Rigid Gas Permeable Lenses Review

PMMA has excellent optical homes and was developed as a light-weight and shatter-resistant alternative to glass for many applications. But it is impermeable to oxygen and other gasses, and the clear front surface area of the eye (cornea) requires a significant supply of oxygen to remain healthy.

Given that oxygen can not travel through a PMMA contact lens, the only method for this crucial element to reach the cornea was for tears to wash underneath the lens with each blink. In order for this blink-induced, tear-pumping action to happen, PMMA lenses needed to be made relatively small in size. Likewise, there needed to be a considerable space in between the edge of the lens and the surface area of the cornea.

These style characteristics made many individuals very aware of PMMA lenses on their eyes or triggered discomfort that made wearing the lenses difficult. In many cases, these functions likewise caused problems with PMMA lenses popping off the eye, particularly during sports.

 

Gas Permeable Contact Lenses

What Makes Gas Permeable Lenses Different?

Gas permeable contacts were first presented in the late 1970s; they are really a newer innovation than soft lenses. A lot of GP lenses integrate silicone, that makes them more flexible than PMMA.

And silicone is oxygen permeable, so oxygen can pass straight through GP lenses to keep the cornea healthy without needing to rely entirely on oxygen-containing tears to be pumped under the lens with each blink.

In truth, modern stiff gas permeable contacts allow more oxygen to reach the cornea than the majority of soft contact lenses (although some silicone hydrogel soft lenses are similar to GP lenses in oxygen transmission).

Because gas permeable contact lenses permit oxygen to travel through them, GP lenses can be made larger than PMMA difficult contact lenses, and the edges of GP lenses can be fitted closer to the surface area of the eye. These design modifications make contemporary stiff GP lenses more comfy and much easier to obtain used to than old-fashioned tough contacts and also keep the lenses more firmly on the eye when used during sports and other activities.

RGP lenses likewise provide better vision, resilience, and deposit resistance than soft contact lenses. And due to the fact that they last longer than soft lenses, they can be less expensive in the long term.

Also read: Overnight Contact Lens: Ortho-K Lenses to Correct Myopia

Adjusting To RGP Lenses

So why doesn’t everyone wear gas permeable lenses? Mostly since soft lenses are instantly comfortable, and GP lenses need an adjustment period prior to they are as comfortable as soft contacts.

Some other drawbacks of RGP lenses are talked about below.

The Benefits Of RGP Lenses

Gas permeable contact lenses offer some impressive benefits over soft lenses. For one, because GP lenses are made from a firm plastic product, they maintain their shape when you blink, which tends to provide sharper vision than flexible soft lenses.

GP lenses likewise are exceptionally long lasting. 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 do not include water (as soft contact lenses do), so protein and lipids from your tears do not comply with GP lenses as easily as they do to soft lenses.

With a little care, gas permeable contact lenses can last for many years, as long as you don’t need a prescription change.

Niches Where GP Contact Lenses Excel

Though they are less popular than soft lenses, gas permeable contacts are the best choice for many people, including:

  • People who are very critical and want to go through a period of adjustment to get in touch with lens wear to accomplish the sharpest vision possible.
  • Some individuals with astigmatism for whom soft contacts do not produce the desired visual skill. [Check out contacts for astigmatism.]
  • Individuals with presbyopia, because GP lenses come in many bifocal and multifocal designs. Various bifocal designs work well for different individuals, so having numerous choices is a real plus. Likewise, many individuals discover that the best mix of near and range skill is obtained with GP bifocals.
  • Individuals who have a condition called keratoconus, where the cornea is cone-shaped and causes severe visual distortion.
  • People who need contact lenses after refractive surgery.

Gas permeable contacts also are used for ortho-k, where specially created GP lenses are worn during sleep to improve the cornea and enhance vision.

See also: Bifocal Contact Lenses

Limitations Of Gas Permeable Lenses

Unlike soft lenses, to achieve maximum convenience with gas permeable contacts, you need to wear them frequently (though not always every day).

If you don’t use your soft lenses for a week, they’ll still be comfortable when you put them on a week later on. But if you do not use your GP lenses for a week, you’ll probably need some time to get comfy once again.

Likewise, GP lenses are smaller in size than soft lenses, which indicates there is a higher risk of gas permeable lenses dislodging from the eye during sports or other activities.

And because gas permeable lenses are developed to move on the eye when the wearer blinks, there is a higher risk of dust and debris getting under the lenses, triggering pain or a possible abrasion to the cornea.

Finally, GP lenses do require care, given that they are reused for one year or more.

Hybrid Contacts: The Best Of Both Worlds?

Since convenience is the main barrier to greater popularity of gas permeable lenses, hybrid contact lenses are an outstanding option for individuals who desire the clearness of a GP lens and using comfort that more carefully looks like that of soft lenses.

Hybrid contact lenses have a main optical zone that is made from a gas permeable lens product, surrounded by a peripheral fitting zone made from silicone hydrogel or routine hydrogel soft lens material.

SynergEyes presently is the sole manufacturer of FDA-approved hybrid contact lenses sold in the United States. The company makes a variety of hybrid lenses sold under the Duette, UltraHealth and SynergEyes brands, consisting of progressive and multifocal hybrid lenses for the correction of presbyopia and styles for the correction of keratoconus and other corneal problems.

See also: Contact Lenses for Keratoconus, Astigmatism, Dry Eyes and Other Eye Disease

For additional information about gas permeable lenses, go to the GP contacts educational site supplied by the Contact Lens Manufacturers Association. Also, seek advice from your eye care specialist and ask if gas permeable contacts (or perhaps hybrid contact lenses) are the best option for your lifestyle and visual needs.

Dr. D.Roberts / author of the article
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Ophthalmology: Health of Your Eyes
Comments: 1
  1. Kenneth Spencer

    I have actually been using GP lenses for the last 16 years and I’ve not had any issues with them. They do handle a lot more abuse than soft lenses. It took me a few weeks to get used to them and at first they seemed like I had a swelling of brick dust in each eye. Now I wouldn’t lack them. They give a better level of correction than my glasses specifically with my level of short sightedness.

    I have to change my existing pair soon however I have had them for about three years now. Most likely a bit too long but I have not had any issues with them.

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