Rigid gas permeable (RGP) contact lenses, also known as oxygen permeable lenses, are today’s most state-of-the-art hard contact lenses.

Many of today’s RGPs are made with silicone, which makes a more flexible plastic than PMMA. Today’s new RGP materials also allow oxygen to pass to your eyes, something that did not happen with PMMA. In fact, RGPs transmit more oxygen to the eye than do most soft contact lenses. The result is that today there is a selection of more comfortable hard contact lenses that provide better eye health.

The Benefits of RGPs

On the other hand, there are some outstanding benefits offered by RGPs over soft lenses. For one, because an RGP is a stiff material, it retains its shape well when you blink, which tends to provide crisper vision than would a soft lens. Also, RGPs are extremely durable. With proper lens care, they may last years, as long as you don’t require a prescription change.

They’re also easier to care for than soft lenses, for two reasons: Because they’re rigid, they’re easier to handle. And, because they’re made of materials that don't contain water (as soft contact lenses do), protein and lipids from your tears do not bind to RGPs as readily as they do to soft lenses. For both RGPs and soft lenses these deposits, if not removed, will impede vision and can cause potentially serious eye conditions like a corneal abrasion.

Bifocal contact lenses are designed to give good vision to people who have a condition called presbyopia. The key sign that you're developing presbyopia is that you need to hold reading material, like a menu, further from your eyes to see it clearly.

Bifocal contacts are available in both soft and rigid gas permeable materials.

Today’s bifocal contact lenses are even available in a disposable or frequent replacement wear regimen. That means you can have the convenience of throwing the lenses out at specified intervals and replacing them with fresh, new lenses. Disposable bifocal contact lens first became readily available in 1999.

Bifocal contact lenses work much like bifocal eyeglasses:

They have two powers on one lens: one to correct distance vision, if that’s needed, and the other to correct near vision.

Some contact lens designs feature two "obvious" prescriptions, with the distance vision on the top of the lens and the near vision at the bottom, similar to a bifocal eyeglass with a line separating the powers. Other designs work more like progressive eyeglass lenses, where the different prescriptive powers are blended on different parts of the lens. Your eye learns to differentiate the proper power for the correct distance.

Disposable and frequent replacement contact lenses are designed to be worn for a specific period of time, thrown out and replaced with a fresh pair of lenses.

These types of lenses were brought on by advances in contact lens manufacturing that made lenses cheaper to produce in large quantities. Therefore, some of the disposable and frequent replacement lenses currently available are not actually new lens materials. Some are lenses that have been on the market for years but only recently have been packaged in multipacks for regular replacement.

Disposable and frequent replacement lenses have become quite popular because they make contact lens wear more healthy for your eyes and more convenient. They are available for a variety of replacement schedules including daily, weekly, biweekly, monthly, semi-monthly and quarterly. "Disposable" generally refers specifically to lenses that are replaced every two weeks or less; contacts that are replaced monthly to quarterly are "frequent replacement." The more often you wish to wear a new pair, the more lenses you’ll need and the higher the cost will be.

These contacts are still not meant to replace sunglasses. A contact lens only covers your cornea, not your entire eye. A sunglass with UV protection can cover more of your eye and the parts of your face that surround the eye, depending on the size of the sunglass lens. That’s why contacts with UV blockers are designed to complement sunglass use as an added protection.

These are the typical steps for good lens care:

1. Wash your hands, then dry them with a lint-free towel.
2. Remove your lenses and clean them. This usually involves putting some solution on the lens while it is in your hand, then taking the index finger of your other hand and gently rubbing your lens in the solution. The cleaning process removes dirt, other debris and mucous from the lens.
3. Rinse your lenses by running a small stream of solution over the lens in your hand.
4. Put your lenses in a lens case filled with disinfecting/storage solution. The disinfecting process gets rid of potentially sight-threatening organisms on the lens.
5. The next time you wear the lenses, remove them from the case, rinse them and insert.

Enzymatic Cleaners

Some eyecare professionals will also recommend using an enzymatic cleaner, either daily, weekly or monthly. These are particularly useful for people who tend to develop protein deposits on their lenses.

Enzymatic cleaners used to consist of a small tablet that was dropped into a solution with the lens. Today, there are one-bottle enzymatic cleaners, and you simply need to add a drop of the solution to your lens while it’s in the case filled with disinfecting solution.

In general, rigid gas permeable contact lenses (RGPs) are easier to care for than soft contact lenses. Because they are usually made of a combination of silicone and fluorine, they do not tend to attract proteins and other deposits as readily as do soft lenses. Hence, the cleaning process is designed to remove debris and dirt and soaking after cleaning is a conditioning procedure to keep them comfortable.

On the other hand, the older the RGP, the more difficult it can be to clean. (While RGPs can crack or chip over time -- which may require replacement -- if your typical cleaning regimen seems to stop working, you may be able to have your RGPs polished. Ask your eyecare professional about this option).

Use the care system that your eyecare practitioner recommends. Usually this will involve lightly rubbing a cleaning solution in the lens with your index finger, rinsing the lens and storing it in a contact lens case filled with a storing/conditioning solution. These steps ought to occur after you’ve thoroughly washed and dried your hands.

Water is not a replacement for a store-bought care system recommended by your eyecare professional. Water can compromise your lenses, causing them to become uncomfortable. Your eyecare professional may also recommend adding an enzymatic cleaner to your regular lens care regimen to help remove protein deposits.

Your entire cleaning system may be available in just one bottle that functions as a cleaning, disinfecting and storing solution -- two if you need an enzymatic cleaner. While your cleaning regimen will usually be required each day, if you have daily wear lenses (those that are removed every night), the enzymatic cleaner is usually only required once a week.

It’s also important to clean, rinse and air-dry your contact lens case after each use. Some practitioners recommend using the storage solution, not water, for this process.

Not all solutions designed for soft lenses are also designed for RGPs. Do not switch solutions or use a product that was not recommended by your eyecare professional. You could damage your lenses and/or your eye health.