CONTACT LENS BASIC

Contact lenses, like eyeglasses or LASIK, can correct your nearsightedness, farsightedness and astigmatism. Among Americans who need vision correction, about 20 percent wear contact lenses.

While some people enjoy making a fashion statement with eyeglasses, others prefer their appearance without them. Contact lenses can achieve this without irreversible refractive surgery. Contact lenses can also provide a full field of unobstructed vision, which is great for sports.

Contact lenses have been around for more than a hundred years. During that time, many advancements have allowed just about everyone to wear contact lenses. If you were told in the past that you couldn't wear contact lenses, odds are that's not true today. There are more convenient and healthy contact lens options than ever.

If you're new to contact lenses, your first step is to see an eye care practitioner. In the United States, contact lenses are a prescription item, just like pharmaceuticals. They must be prescribed and properly fitted by an eye care professional (ECP). Your ECP will evaluate your visual needs, your eye structure, and your tears to help determine the best type of lens for you.

The many types of contact lenses currently available can be grouped in various ways according to:

What they're made of

How long you wear them without removal

How often you dispose of them

The design of the lens​

Contact Lens Materials

Classified by material, there are three types of contact lenses:

Soft lenses are made from gel-like, water-containing plastics called hydrogels, and cover the entire cornea. Silicone Hydrogel Lenses are an advanced type of soft lens that transmit more oxygen to the eye than regular hydrogel soft lenses.

GP lenses, also known as RGP (Rigid Gas Permeable Contact Lenses), are made from rigid, waterless plastics and are especially good for Presbyopia and high astigmatism. GP lenses are smaller in diameter and often provide sharper vision than soft lenses.

Hard lenses are made from a rigid plastic material called PMMA that does not transmit oxygen to the eye. These lenses have virtually been replaced by GP lenses and are rarely prescribed today.

Also, hybrid contact lenses have an optical center made of a rigid GP lens material, surrounded by a zone of soft lens material for greater wearing comfort.

Silicone hydrogel contact lenses are the most popular lenses in the United States, accounting for 67 percent of new contact lens fittings and refittings in 2011. Regular soft lenses accounted for 24 percent, followed by GP lenses (8 percent) and hybrid lenses (1 percent).*

Contact Lens Wearing Time

Until 1979, everyone who wore contact lenses removed and cleaned them nightly. The introduction of "extended wear" enabled wearers to sleep in their contacts. Now, two types of lenses are classified by wearing time:

• Daily wear — must be removed nightly
• Extended wear — can be worn overnight, usually for seven days consecutively without removal

"Continuous wear" is a term that's sometimes used to describe 30 consecutive nights of lens wear — the maximum wearing time approved by the FDA for certain brands of extended wear lenses.

Disposal Intervals for Contact Lenses

Even with proper care, contact lenses (especially soft contacts) should be replaced frequently to prevent the build-up of lens deposits and contamination that increase the risk of eye infections.

Soft lenses have these general classifications, based on how frequently they should be discarded:                                                                 

• Daily disposable lenses — Discard after a single day of wear
• Disposable lenses — Discard every two weeks, or sooner
• Frequent replacement lenses — Discard monthly or quarterly
• Traditional (reusable) lenses — Discard every six months or longer

Gas permeable contact lenses are more resistant to lens deposits and don't need to be discarded as frequently as soft lenses. Often, GP lenses can last a year or longer before they need to be replaced.

Which Contact Lens Is Right for You?

First, your contacts must address the problem that is prompting you to wear lenses in the first place. Your contact lenses must provide good vision by correcting your myopia, hyperopia, astigmatism, or some combination of those vision problems.

Second, the lens must fit your eye. To do that, lenses come in tens of thousands of combinations of diameter and curvature. Of course, not every lens brand comes in every "size."

Your ECP is skilled in evaluating your eye's physiology, and your eyesight, to determine which lens best satisfies the two criteria above.

Third, you may have another medical need that drives the choice of lens. For example, your ECP might pick a particular lens if your eyes tend to be dry.

Finally, consider your "wish list" of contact lens features — colors, for example, or overnight wear.

When you and your ECP decide on the right lens for you, you'll be given a contact lens prescription. You'll be able to buy a supply of lenses from your ECP or from the many other outlets that sell contact lenses.

Contact Lens Wear and Care

Caring for your contact lenses — cleaning, disinfecting and storing them — is much easier than it used to be.

A few years ago, you would have needed several bottles of cleaning products, and perhaps enzyme tablets, for proper care. Today, most people can use "multipurpose" solutions — meaning that one product both cleans and disinfects, and is used for storage.

People who are sensitive to the preservatives in multipurpose solutions might need preservative-free systems, such as those containing hydrogen peroxide. These do an excellent job of cleaning contacts, but it's very important to follow the directions for using them. The solution should not come into contact with your eyes until soaking is complete and the solution is neutralized.

Of course, you can avoid lens care altogether by wearing daily disposable contact lenses.

Contact Lens Problems​

Trial and error often is involved in finding the perfect lens for you. People react differently to various lens materials and cleaning solutions.

Also, the correct "parameters" of your lens — that is, power, diameter, and curvature — can be finalized only after you've successfully worn the lens. This is especially true for more complex fits involving extra parameters, such as with bifocals or toric contact lenses for astigmatism.

If you experience discomfort or poor vision when wearing contact lenses, chances are that an adjustment or change of lens can help.

Today, more contact lens choices than ever are available to provide comfort, good vision, and healthy eyes. If your eyes or lenses are uncomfortable or you are not seeing well, remove your lenses and visit your eye care professional to explore available remedies for contact lens discomfort.

Buying Contact Lenses 

You can buy replacement contact lenses at many places, and some offer a better value than others. Find out more about where to buy contacts and buying contact lenses online.