All about contact lenses

In this section we bring you a basic introduction to contact lenses. Materials are taken from allaboutvision.com, we encourage you to browse trough their web to find more detailed answers to the questions you might have.

Don't forget that regular visits at your optometrist and knowledge of rules of lens care are necessary to ensure safe and comfortable experience of wearing contact lenses. They are necessary to avoid discomfort, inflammation, swelling, abrasion, or another problem that could result in eye tissue damage.

Contact lenses are used to correct your nearsightedness, farsightedness and astigmatism. If you were told in the past that you couldn't wear contact lenses, odds are that's not true today. If you're new to contact lenses, your first step is to see an eye care professional (ECP) who will determine what type of lenses you need. 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 two main types of contact lenses:

Soft lenses -

made from gel-like, water-containing plastics, and are most common. They're a bit larger in size than your iris.

GP lenses -

gas permeable, also known as RGP or "oxygen permeable" lenses, are made from rigid, waterless plastics and are especially good for presbyopia and high astigmatism. These lenses are usually about eight millimeters in diameter, which is smaller than your iris. From the introduction of soft lenses in 1971 until several years ago, most lens brands were made from "hydrogel" plastics. Then silicone hydrogel contact lenses were introduced. They have become the contact lenses of choice for many eye care practitioners, because they allow more oxygen to pass through the lens to the eye, and they are less prone to dehydration.

Contact Lens Wearing Time

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 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.

Contact Lens Designs

Many lens designs are available to correct various types of vision problems:

Spherical contact lenses -

are the typical, rounded design of contact lenses, which can correct myopia (nearsightedness) or hyperopia (farsightedness)

Bifocal contact lenses -

contain different zones for near and far vision to correct presbyopia [more about bifocal contacts]

Orthokeratology lenses -

are specially designed to reshape the cornea during sleep, providing lens-free daytime wear [more about ortho-k]

Toric contact lenses -

correct for astigmatism, as well as for myopia and hyperopia [more about toric contacts]

All of these lenses can be custom made for hard-to-fit eyes. Many other additional lens designs are available. Typically these are less common and fabricated for use in special situations, such as correcting for keratoconus.

More Contact Lens Features

Contacts for Dry Eyes -

certain soft contact lenses are specially made to reduce the risk of contact lens-related dry eye symptoms [more about contact lenses for dry eyes]

Colored lenses -

many of the types of lenses described above also come in colors that can enhance the natural color of your eyes - that is, make your green eyes even greener, for example. Or these lenses can totally change the eye's appearance, as in from brown to blue [more about colored lenses]

Special-Effect lenses -

also called theatrical, novelty, or costume lenses, these take coloration one step further to make you look like a cat, a zombie, or another alter-ego of your choice [more about special-effect contacts]

Prosthetic lenses -

colored contact lenses can also be used for more medically oriented purposes. People with disfigured eyes, as a result of accidents or disease, can use a custom, opaque colored lens to mask the disfigurement and match the appearance of their normal eye [more about prosthetic contacts]

UV-Inhibiting Lenses -

today, many contacts incorporate an ultraviolet blocker in the lens material, to cut down on UV light that can eventually cause cataracts and other eye problems. You can't see this blocker by looking at the lens. And since contacts don't cover your entire eye, UV blockers cannot substitute for traditional sun protection like good quality sunglasses.

Hybrid lenses -

one brand of lenses features a GP center with a soft outer skirt, providing wearers with both the crisp optics of a rigid lens and the comfort of a larger, soft lens

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.

Comparing different lens types

Lens Type	Advantages	Disadvantages
Rigid gas-permeable(RGP) Made of slightly flexible plastics that allow oxygen to pass through to the eyes.	excellent vision short adaptation period comfortable to wear correct most vision problems easy to put on and to care for durable with a relatively long life available in tints (for handling purposes) and bifocals	require consistent wear to maintain adaptation can slip off center of eye more easily than other types debris can easily get under the lenses requires office visits for follow-up care
Daily-wear soft lenses Made of soft, flexible plastic that allows oxygen to pass through to the eyes.	very short adaptation period more comfortable and more difficult to dislodge than RGP lenses available in tints and bifocals great for active lifestyles	do not correct all vision problems vision may not be as sharp as with RGP lenses require regular office visits for follow-up care lenses soil easily and must be replaced
Extended-wear Available for overnight wear in soft or RGP lenses.	Can usually be worn up to seven days without removal	do not correct all vision problems require regular office visits for follow-up care increases risk of complication requires regular monitoring and professional care
Extended-wear disposable Soft lenses worn for an extended period of time, from one to six days and then discarded.	require little or no cleaning minimal risk of eye infection if wearing instructions are followed available in tints and bifocals spare lenses available	vision may not be as sharp as RGP lenses do not correct all vision problems handling may be more difficult
Planned replacement Soft daily wear lenses that are replaced on a planned schedule, most often either every two weeks, monthly or quarterly.	require simplified cleaning and disinfection good for eye health available in most prescriptions	vision may not be as sharp as RGP lenses do not correct all vision problems handling may be more difficult

These tips can help you deal with everyday contact lens concerns.

Is My Contact Lens Inside Out?

A question many newbie wearers have is: "How can I tell if my contact lens is inside-out?"

The difference can be subtle, but before placing a contact lens on your eye, make sure it looks like half a ball, not a soup bowl with a rim. The trick is to place the lens on your finger so that a cup is formed. Then hold the lens up directly in front of your eyes so you're looking at the side of the cup.

If the lens forms a "U" with the top edges flared out, it's inside out. If it forms just a "U," it's in the correct position.

If you're wearing lenses with a handling tint, another way is to place the lens on your fingertip and then look down at it. The edge of a tinted lens should look very blue (or green, depending on the tint); that won't be the case if the lens is inverted.

 

Some contact lenses also have a laser marking, such as the brand name, on the edge to help you. If you can read it properly, the lens is not inside out.

Don't worry if you place a contact lens in your eye inside out. The lens will feel uncomfortable, but it can't do any damage.

Applying Your Contact Lenses

Make sure you wash your hands thoroughly before applying your contact lenses, but avoid scented or oily soaps that might adhere to the lens surface. Especially avoid using products containing lanolin and moisturizing lotions.

Some eye doctors say to always apply the first contact lens in the same eye, so you'll avoid the possibility of mixing up lenses for the right eye and left eye.

Other basic guidelines for contact lens application include:

• Gently shake your lens case containing the storage solution, to loosen the contact lens should it be stuck. (Don't try pulling at the lens with your finger, or you might damage it.)
• Slide the lens out of its case and into the palm of your hand. Rinse thoroughly with the appropriate contact lens solution.
• Place the contact lens on the tip of your index or middle finger, which should be dry or mostly dry.
• With the fingers and thumb of your other hand, simultaneously pull up on your upper eyelid and down on your lower eyelid.
• Position the lens on your eye while looking upward or forward, whichever you find to be easier. You also can apply the contact lens by placing it on the white of the eye closest to your ear.
• Gently close your eye, roll your eyes in a complete circle to help the lens settle, and then blink.
• Look closely in the mirror to make sure the lens is centered on your eye. If it is, the lens should be comfortable and your vision should be clear.

Removing Your Contact Lenses

Always wash your hands before removing contact lenses. If you are standing in front of a sink, use a clean paper towel to cover the drain where the contact lens might accidentally fall.

To remove soft contact lenses, look upward or sideways while you pull down on your lower eyelid. With a finger, gently maneuver the lens onto the white of your eye. There, you can very gently pinch the lens together with your index finger and thumb and lift it off the eye.

Until you master contact lens removal, you might want to keep your fingernails short to avoid accidentally scratching and damaging your eye.

Rigid contact lenses can be removed by holding out the palm of your hand, bending over, and then opening your eye wide. With one finger of your other hand, pull the skin between your upper and lower eyelid (just outside the lateral aspect of your eye) outward toward your ear with your eye wide open. Then blink. The contact lens should pop right out and into your open palm.

Devices for removing contact lenses, called "plungers," also are available from your eye doctor, and can be used to touch and directly remove a lens from your eye. Just make sure you touch only the lens and not your eye's surface with these devices.

While you might hear a myth or two about someone "losing" a contact lens in the back of the eye, this is actually impossible because of a membrane that connects your eye to the back of your eyelid.

Before we get started, understand that you should not switch care regimens without asking your eye doctor first. Some products are not compatible with each other, or with certain contact lenses. Using incompatible products can ruin your contact lenses or harm your eyes.

To make sense of all the bottles and boxes, it helps to know what steps are required to care for soft contacts.

It's particularly important to follow guidelines for safe handling of soft contact lenses in light of recent outbreaks of serious fungal eye infections associated with a popular (now discontinued) brand of contact lens cleaning/disinfecting solution.

The Basics of Soft Contact Lens Care: Clean, Rinse and Disinfect

1. Wash your hands so that you don't transfer dirt and germs to your eye. Try to avoid moisturizing soaps, as they are not good for contact lenses. Dry your hands with a lint-free towel.
2. Remove one lens and clean it with the recommended solution. Cleaning removes eye-produced buildup, cosmetics and other debris that impairs lens comfort. The FDA recommends that you rub the lens in the palm of your hand with a few drops of solution, even if you are using a "no-rub" product.
3. Rinse the lens again to remove the loosened debris, making sure to take as long as the package directs: Rinsing is an important step.
4. Place the lens in your clean lens case or lens holder and fill with fresh solution; don't "top off" your old solution. Disinfecting kills microorganisms on the lens. Disinfection time varies from product to product; check the package for details.
5. Repeat steps two through four for your other lens.

Beyond Clean, Rinse and Disinfect

Protein - depending on what kind of contact lenses you wear and how much protein your eyes deposit on your contacts, your doctor may recommend you use a product for protein removal.

While cleaning them does remove some protein, it can still build up on your lenses and make them uncomfortable. That's why the longer you wear lenses before replacing them, the more likely you are to need a protein remover.

For example, if you wear disposables, you probably won't need one; but if you wear the kind of lenses that are replaced only once or twice a year, you definitely will. Products for removing protein include enzymatic cleaner and daily protein removal liquids.

Eye dryness and irritation - use contact lens eye drops to lubricate your eyes and rewet your lenses.

Eye sensitivity and allergies - a small percentage of lens wearers develop an eye allergy to the chemicals present in contact lens solutions. If this is the case with you, you don't need an additional product: You just need to switch products to those marked "preservative-free."

Do

• Always wash your hands before handling contact lenses.
• Carefully and regularly clean contact lenses, as directed by your optometrist. If recommended, rub the contact lenses with fingers and rinse thoroughly before soaking lenses overnight in sufficient multi-purpose solution to completely cover the lens.
• Store lenses in the proper lens storage case and replace the case at a minimum of every three months. Clean the case after each use, and keep it open and dry between cleanings.
• Only fresh solution should be used to clean and store contact lenses. Never Re-use old solution. Contact lens solution must be changed according to the manufacturer's recommendations, even if the lenses are not used daily.
• Always follow the recommended contact lens replacement schedule prescribed by your optometrist.
• Remove contact lenses before swimming or entering a hot tub.
• Avoid tap water to wash or store contact lenses or lens cases.
• See your optometrist for your regularly scheduled contact lens and eye examination.

Don't

• Use cream soaps. They can leave a film on your hands that can transfer to the lenses.
• Use homemade saline solutions. Improper use of homemade saline solutions has been linked with a potentially blinding condition among soft lens wearers.
• Put contact lenses in your mouth or moisten them with saliva, which is full of bacteria and a potential source of infection.
• Use tap water to wash or store contact lenses or lens cases.
• Share lenses with others.
• Use products not recommended by your optometrist to clean and disinfect your lenses. Saline solution and rewetting drops are not designed to disinfect lenses.