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Contact lenses

Contact lenses

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Contact lenses

Contact lenses

Almost everyone can wear contact lenses. Lens types and materials have advanced remarkably in the past ten years. More people can wear comfortable contact lenses that fit their lifestyle and occupational needs. Contact lenses can correct myopia, hyperopia, astigmatism and presbyopia. People with more exotic prescriptions are more difficult but not always impossible to fit. Even children can wear contacts, particularly if they are active in sports. Contact lenses are great for people who golf or participate in other outdoor activities. They are fashionable, fun and can even change your eye color. Proper lens care is important for anyone who wears contact lenses.

A good candidate for contact lenses?

A Contact Lense for Almost Every Eye

There is a contact lens for almost every eye. So many different types of lenses are available that eye doctors (optometrists or ophthalmologists) can fit most people who have a simple prescription.

Contact lenses can correct myopia (nearsightedness), hyperopia (farsightedness), astigmatism (distorted vision), and presbyopia (aging eyes that need bifocals). Contact lenses can help people to focus properly after surgery to remove a cataract (cloudy lens) or correct the vision of someone with mild to moderate keratoconus (bulging cornea).

Because they have no frames and move when your eye moves, contact lenses offer a wider field of vision than eyeglasses. They don’t fog up in cold or rainy weather, obscure vision or get in the way of activities.

The ideal candidate for contact lens wear is someone with a moderate amount of myopia, average corneal shape and good healthy eye. But eye doctors (optometrists or ophthalmologists) can even fit people with irregular corneas and large corrections after a thorough eye examination.

For greater comfort and eye safety, contact lenses should be properly fit and periodically checked by an optometrist.

Getting fit

During contact lens fitting, the optometrist helps you to select the contact lens — the lens material and design — that’s right for you. More than physically fitting the lens on the eye, this evaluation determines what type of wear system fits your personal needs.

The answer is based on your prescription, corneal shape, lifestyle, vocation and budget.

For example, are you a better candidate for rigid gas permeable (RGP) or disposable soft contact lenses? How often will you clean your lenses? Do you prefer to wear contact lenses on a daily, weekly or monthly basis? Do you play sports or need UV (ultraviolet) protection?

These are just a few questions that your eye doctor will ask to help you to determine your needs.

Poor candidates for contact lenses

Most people who need vision correction can wear contact lenses, but some are poor candidates for successful lens wear. They include people with:

- frequent eye infections
- a dusty or dirty work environment
- eye health problems, e.g., chronic glaucoma
- other health problems, e.g., diabetes
- allergies

Eye too dry?

People who suffer from dry eye or allergies, such as hay fever, may be poor candidates for contact lens wear. Older people are more likely to have dryness problems, as are people who use certain medications, such as birth control pills.

These people are more sensitive to contact lenses. They may react to lens care products or develop a hypersensitivity to protein deposits that stick to contact lenses.

About 5% to 10% of people who try to wear contact lenses fall into this category. That means that about 1 in 20 people who seem to be good candidates for contact lenses may have problems – either because they’re too sensitive to lens care solutions or their eyes dry out too fast when they wear contact lenses.

People often don’t feel any dryness, until they start to wear contact lenses. Some people cannot even wear disposable daily soft lenses on a regular basis. However, they may be able to wear soft contact lenses on alternate days or adhere to a one-day-on, three-days-off wearing schedule. For that reason, it’s almost impossible to predict who will be an unsuitable candidate for contact lens wear.

No care, no wear

Today’s broader selection of disposable soft contact lenses and the introduction of multipurpose solutions have opened the contact lens field to people with no patience for complex lens-care regimens.

Despite these advances, noncompliance eliminates about 5% of patients from contact lens wear. Some people cannot afford daily disposable lenses, but they do not care for their lenses. Improper lens care may lead to hypersensitivity reactions or eye infections.

If you feel that caring for contact lenses is too much work, eyeglasses may be a better choice for daily eyewear.

Common problems

Most people who find it difficult to wear contact lenses complain of excessive tearing, eye itchiness, light sensitivity, a dry or burning sensation and, occasionally, blurred or distorted vision. Eye cosmetics may settle on the lenses, causing irritation. Most of these problems are caused by improper lens care.

Health precautions

Too often, people forget that contact lenses are a medical device.

A major U.S. study has found that overnight use of extended-wear contact lenses increases the risk of corneal ulcers (ulcerative keratitis). These wounds can scar the cornea, leading to vision loss. For that reason, extended-wear lenses have fallen out of favor with many eyecare professionals.

The U.S. Food & Drug Administration has reduced the recommended wear time for soft disposable contact lenses from 30 days to 7 days.

Smoking and contact lenses don’t mix. Smokers who wear contacts are 8 times more likely to develop corneal ulcers than nonsmokers who wear contacts, regardless of lens type.

Follow-up is important

Eye doctors (optometrists or ophthalmologists) usually see contact lens wearers for their first follow-up within 7 to 10 days of their initial fitting, then 2 to 4 weeks later, at 8 weeks, 12 weeks, and every 6 months. Establishing a long-term relationship with your eyecare professional is important, so he or she can observe how the cornea reacts to contact lens wear over time.

Small, plastic discs about the size of a dime, contact lenses float comfortably over the cornea (the eye’s window) on a natural layer of tears. They can correct myopia, hyperopia, astigmatism and presbyopia.

Over the past decade, a revolution in contact lens technology has created a host of new lens materials and wear options — from soft disposable lenses that contain anywhere from 36% to 74% water to rigid gas permeable lenses (RGPs) for almost all optical corrections. Some contact lenses even combine soft and RGP materials for specific fitting needs.

Basically, there are three types of contact lenses: hard, RGP and soft. Wear and replacement schedules vary for each type of lens.

The original contact lenses

Hard plastic (PMMA) lenses are the original contact lenses. These high-maintenance lenses are now considered obsolete. Hard lenses are non-gas permeable — little oxygen passes through them to the cornea. For this reason, they should not be worn for more than 12 hours. They usually require a long adjustment period.

RGP Lenses

About 17% of people who wear contacts have RGP lenses.

Rigid, gas-permeable lenses are more comfortable than hard plastic lenses and healthier for the eyes, because they "breathe". They allow oxygen to flow through the lens to the cornea. For this reason, they can be worn longer than hard lenses.

Two types of RGPs are available: daily wear (worn during the day and removed at night) and extended wear (can be worn continuously, including overnight, for a few days in a row).

Because RGPs have a low water content, they resist protein deposits and are less likely to harbor bacteria than soft lenses. They provide clearer, sharper vision than soft lenses. They are also easier to handle. Some RGPs come with a locator tint — a blue tint that doesn’t change eye color when worn — that make them easier to find and place in the eye. RGPs last up to a year or two before needing replacement.

RGP lenses are custom-fit by an optometrist to correct astigmatism, near- and farsightedness, and presbyopia. They require some adaptation time. They also require routine daily cleaning. Overall, they are less expensive and more durable than soft contacts.

Soft contact lenses

Most people wear soft disposable lenses. Soft contacts are made from a gel-like plastic. They contain from 38% to 79% water, so they are more comfortable to wear. Plenty of oxygen reaches the cornea through the soft, porous lens.

Vision is not as sharp as with RGPs, but most people are more than satisfied with soft contacts. They are meant for short-term wear only, as the high water content means that bacteria can be trapped in the porous surface if the lenses are not cleaned. Protein deposits also tend to build up on soft contacts, leading to discomfort.

Soft contacts are available in daily, weekly or monthly disposable packages. As with RGPs, soft contact lenses can be worn on a daily or extended basis.

If worn on a weekly or longer basis, soft contact lenses should be cleaned like other contact lenses.

If someone offered you a soft contact lens from a debris-encrusted case, would you stick it in your eye? Surprisingly, many people make this unhealthy choice on a daily basis.

Improper lens care accounts for the two most common problems of contact lens wear: lens discomfort and risk of infection. In extreme cases, infections from bacteria, fungi and other contaminants on dirty contact lenses can lead to vision loss.

Caring for your lenses

On the naked eye, tears cleanse the cornea by washing away a biofilm of microbes and protein. Sterile contact lenses are coated by this biofilm within seconds of placement in the eye. They too must be washed, except tears cannot free microbial debris trapped beneath the lenses. If improperly cleaned, the build-up of organisms can lead to eye infections.

Protein adheres to soft contact lenses at an alarming rate. Deposits are detectable after less than one minute of wear. On the microscopic lens surface, they resemble a miniature coral reef — one that greatly influences lens comfort.

There's a simple way to avoid lens discomfort and the risk of infection: start every day with a new pair of disposables. But many people can't afford this option. So, what's the best way to clean soft disposable and rigid gas-permeable (RGP) contacts for a healthy, comfortable lens-wearing experience?

Double, double, toil and trouble

For some people, lens care is like bad witchcraft — too much time and trouble for too little gain. The fact is that many people stop wearing contacts, because they can't be bothered with complex lens-care regimens. They literally shelve their lenses rather than remove uncomfortable protein deposits.

Over the last few decades, the lens-care industry has evolved to respond to consumer's demand for a simpler but safer lens-cleaning process. Manufacturers have invented “all-in-one” multipurpose solutions (MPS) and protein removers to win the war against noncompliance.

Simpler lens-care regimens may reduce the risk of infection and improve lens comfort.
Rub and rinse is the credo of all MPS. Simple digital cleaning — rubbing then rinsing the lens surface with solution — eliminates 90% of threatening microorganisms before disinfection.

Recently, the U.S. Food & Drug Administration (FDA) recognized that some people even avoid the rub-and-rinse step, so it introduced a new standard for lens care — the multipurpose disinfecting solution (MPDS).

This FDA standard requires lens care solutions to reduce bacteria, fungi, yeast and molds without a rub-and-rinse step. Fungi, yeast and mould can grow in improperly dried or dirty contact lens cases. From contaminated cases, they're transferred to contact lenses, then into the eye.

Lens care tips

Here’s a few tips for successful contact lens use and care.

- Wash your hands thoroughly before handling your contacts.
- Wash, clean and air-dry contact lens cases.
- Clean, rinse and disinfect contact lenses stored for more than 12 hours.
- Change contact lens cases monthly.
- After washing with cream soaps or using lotions, which can leave an oily film, avoid handling your contacts.
- Never spit on or wash contacts with tap water to avoid lens contamination with bacteria and other infection-causing microbes.
- Never use a home-made saline solution to clean your lenses, because of the risk of permanent vision loss.
- Replace your contacts regularly, as specified by the lens manufacturer.
- Never wear your lenses beyond their recommended wearing time.

Learning to wear multifocal contact lenses is a bit like marriage. The process requires commitment, compromise and a period of adjustment — but it’s incredibly rewarding.

Who wears multifocal contact lenses?

From 80% to 85% of people who ask for multifocal contacts are switching from regular contacts. The remainder are people who’ve just received their first prescription for presbyopia (aging eyes) or who want a part-time alternative to bifocal eyeglasses.

Lens materials and designs

The choices of multifocal lens materials and designs have never been so diverse. The sky’s the limit — whether you decide to wear traditional multifocal or progressive contact lenses.

Choosing a multifocal lens

When choosing a multifocal lens, there are four key factors to consider: personal preference, lifestyle, lens-care regimen and prescription needs.

Multifocal lenses are customized to fit your prescription and personal needs. Your eye doctor needs to know how you use your eyes — what distances you normally use for work and play. For example, if you are a great reader and don’t drive, you might consider a traditional "Ben Franklin" bifocal contact with a larger lower segment for close-up work. Someone who drives but doesn’t spend as much time on close-up work would choose a traditional lens design with a larger top segment for long-distance viewing.

It may take awhile to get used to multifocal contact lenses. Modern lens technology doesn’t have all the answers. Some compromise may be necessary to achieve the best visual function in all situations.

What are the options?

To correct presbyopia, you may choose to wear normal contact lenses with reading specs or choose monovision or multifocal contact lenses. The best way to decide is to explore these options with your eye doctor (optometrist).


With monovision, a person wears contact lenses that have different prescriptions. The dominant eye is usually corrected for far-distance; the other eye is corrected for near-distance. At first, monovision may seem confusing. In about 80% of people, the brain soon learns to pick up images from the clearly focused eye and ignore fuzzy images in the other.

Some monovision wearers have trouble with driving at night. If this problem persists more than a few days, it may be worthwhile to obtain an eyeglass prescription that corrects the near eye for distance.


Multifocal contact lenses are available in soft or rigid gas-permeable (RGP) materials.

Rigid gas-permeable (RGP) multifocal lenses fall into two design categories: aspheric and segmented translating. On aspheric lenses, the center is reserved for distance viewing. The patient sees near, far and intermediate distances simultaneously. It’s up to the brain to select the proper image. This focal pattern is often referred to as a “bull’s eye” design.

Computer users or other patients with intermediate visual demands should consider the aspheric design first. Aspheric RGPs are also a good choice for astigmatic corneas.

With near vision on the bottom and far on top, segmented translating RGPs are the counterpart of “Ben Franklin”-style, bifocal spectacles. When the person looks down, the contact rests on the lower lid, enabling close viewing. Ballast increases the weight and thickness of the bottom segment, so the lens holds its position better.

Segmented translating RGPs work best in people with smaller pupils. They fit flatter than regular contacts. Lower lid position is a crucial factor in proper fit.

Soft multifocal contacts are recommended for people who need small vision corrections for presbyopia. They are appropriate for first- and part-time wearers. Although more comfortable than RGPs, they provide less visual acuity. The manufacturing process is less stable for soft contacts, because it’s more difficult to produce custom-made prescriptions for multifocal distances consistently with soft lens materials.

Although less durable than RGP contacts, soft lenses are disposable and require little or no care if worn on a daily or one-week basis.

Soft multifocals are available in two designs: progressive aspheric and concentric. There are no soft segmented contact lenses. The progressive aspheric contact lens works on the same principle as the RGP design. In the concentric design, near is viewed in the center; far, at the edge. Each segment is distinct; no progressive corridor eases the shift between focal powers.

Soft concentric lenses have a technical advantage over soft aspherics. They can be made for people with higher prescriptions. But, if not well-centered, they can drive the wearer crazy as they shift around the eye.

Mix and match

Monovision and multifocal lenses are not mutually exclusive. Many eye doctors combine the two — a sort of modified monovision — to satisfy people’s needs. Here are a couple of examples.

After one week, a person may find that segmented RGPs are great for reading but poor for distance. In response, the eye doctor may leave the multifocal RGP in one eye, but switch the other to a single-vision lens corrected for better distance vision.

To provide computer users with three effective focal lengths, your eye doctor may prescribe a segmented RGP, skewed for reading and intermediate distance, for one eye, then fit the other eye with a normal distance lens.

Optical roulette

Thanks to technological improvements in manufacturing, over two dozen varieties of multifocal contact lenses are available. The choice and reliability of these products will continue to improve as market demands grow.

Each lens design has unique characteristics. Each manufacturer’s products differ slightly. Most multifocal lenses are made to order. Even slight variations in how your eye doctor prescribes multifocal lenses may affect the outcome.

In short, this is one type of contact lens that won’t be sold by mail-order distributors or at the local pharmacy.

About 45% of people who need visual correction have astigmatism. Toric contact lenses can effectively correct astigmatism (blurred or distorted vision) in many people.

That wasn’t always the case. In the past, contact lens technology was not sophisticated enough to enable contact lens manufacturers to design and consistently reproduce toric lenses to fit people with astigmatism.

Astigmatism is a visual distortion. It happens when the cornea (the eye’s primary focusing lens) has an irregular shape or the crystalline lens inside your eye refracts light irregularly.

When the corneal surface is oblong (cylindrical or toric) rather than round (spherical) – i.e., shaped like a rugby ball instead of a baseball – light rays bend unequally as they pass through it. Instead of a single focusing point, a person with astigmatism has two focusing points. So, images on the retina look blurred or distorted.

Since everyone has a different corneal shape, all toric lenses are different. If you cut a toric lens in half, then examine the cross-section, one part of the lens will probably look thicker than another. There are several reasons why.

Toric lenses are both round and oval at the same time. There are three main designs:

- Front surface toric: The cylinder correction (oval) is placed on the front of the lens. The back surface is round (spherical). This lens design is used for people with little corneal astigmatism (corneal irregularity) but a significant amount of refractive astigmatism (lens irregularity).

- Back surface toric: The cylinder correction (oval) is put on the back of the lens. The front surface is rounded. This lens design is used for people with corneal astigmatism. It also helps to stabilize the lens.

- Bitoric: The cylinder correction (oval) is ground on both front and back surfaces. This lens design is used when a person has significant corneal astigmatism and a toric-shaped cornea. This shape helps to prevent lens movement.

Contact lenses not only move up and down but rotate on the eye. Because of irregular corneal shape, toric lenses are more prone to rotation than normal, spherical lenses. This rotation must be controlled, so a toric lens can provide consistent vision correction. There are several ways to stabilize toric lens movement:

- prism ballast: extra thickness added to the lower portion of the lens helps to control rotation.
- truncation: the lower lens is trimmed to create a flat edge that is aligned with the lower eyelid, aiding stability
- dynamic stabilization: a thick, central zone is edged by thin top and bottom zones, which lie under the upper and lower eyelids for stability

Today, toric lenses are available in soft disposable or rigid gas-permeable (RGP) lens materials.

How do you decide when your child or teen is ready for contacts? The deciding factors are maturity and coordination, not age. Children and teens who follow instructions for proper lens handling and care are good candidates for contact lens wear.

A 3-year study by the Indiana University School of Optometry found that children from 11 to 13 years can handle contacts well and understand how to care for them.

Contact lenses are great for kids who are active in sports. For image-conscious teens, they are a fashionable, natural-looking alternative to eyeglasses. For self-expression, trendy tinted or theatrical contacts are popular options.

Contact lenses are also prescribed to correct some eye problems in children. For babies with vision problems, soft contacts may be preferable to eyeglasses.

Bargain-basement contact lenses are no deal. Often, they end up in the drawer because they don’t fit properly. If your child really wants contacts, take him or her to an eye doctor (optometrist) for a thorough eye examination and proper fitting. Afterwards, the eye doctor will explain and show your child or teen how to care for new contact lenses.

Avoiding problems

Without proper lens care, children and teens can develop common eye problems, such as infections, dry eye or corneal irritation. A few bad habits can cause a lot of lens discomfort. Here are a few important reminders about lens care for children and teens.

Follow the manufacturer’s wearing schedule. If you have daily-wear lenses, extending their wear overnight may endanger your eyes.

Throw-away lenses past their "expiry date". Wearing a lens beyond its time, e.g., keeping a daily disposable lens in your eye for longer than one day, is unhealthy for your eyes. Protein build-up may cause a great deal of discomfort.

Return to your eye doctor for follow-up exams. Contact lenses may subtly change the anatomy of your eyes, so it’s important for your eye doctor to examine your eyes regularly to ensure a proper fit.

Women and contact lenses

About 68% of contact lens wearers are women. Contact lenses complement an active lifestyle. They are functional yet fashionable, correcting vision without interfering with the line of sight. Unlike eyeglasses, they do not distort or hide the natural look of your eyes. And new advances in technology have simplified lens wear and care.

Because women are more prone to dry eye, some find it difficult to wear contact lenses. At certain stages of life, particularly during pregnancy and menopause, hormonal changes may cause dry eye. Contact lenses may feel gritty or scratchy on the eyes. These changes are temporary, but it may help to limit wear time and pay close attention to lens care.

When applying cosmetics, women who wear contact should take special precautions to avoid discomfort or eye infections:

- Insert soft contact lenses BEFORE putting on cosmetics.
- Insert RGP lenses AFTER putting on cosmetics.
- REMOVE contacts before cosmetics.
- Use oil-free moisturizers, which won’t smear your lenses.
- Hands bathed in creams and lotions can leave fingerprint smudges on your contacts.
- Blink often when blow-drying your hair to avoid lens discomfort.
- Eyelash cement, perfume and nail polish can damage your contacts.
- Use hairspray BEFORE inserting your contacts.
- Avoid lash-extending mascara, which contains fibers that may become trapped under or rub against contacts.
- Avoid waterproof mascara, which can stain soft contacts.

Contacts in sports: a competitive edge

In any sport, sharp, clear eyesight makes a difference — whether athletes are keeping their eyes on a target, a ball or the competition. For sports enthusiasts who need vision correction, contact lenses provide a competitive edge — whatever the sport.

Contact lenses give athletes:

- better depth perception
- better peripheral (side) vision
- better visual acuity

With contacts, athletes can judge distances between balls and boundaries more accurately than with eyeglasses. There are no frames to block peripheral (side) views of pursuing competitors. Vision is clearer and sharper, helping athletes focus on details and track their performance more easily. Contact lenses give athletes a clear view without changing the size of objects — a tremendous advantage for nearsighted athletes who see objects through eyeglasses as smaller than their actual size.

Contact lenses don’t fog or smudge in cold weather or get steamed when athletes break into a sweat. They don’t fall into the water at sailing regattas or clatter onto the court during basketball games.

Eye safety in sports is essential, but fitting protective eyewear over eyeglasses can be awkward. With contact lenses, athletes can wear safety goggles comfortably. And, there’s no risk of broken stems or glass.

For more information on contact lenses and sports, contact your eyecare professional.

Sand, water and snow reflect 85% of the sun’s ultraviolet (UV) rays. These rays can damage your eyes, leading to serious eye conditions, e.g., macular degeneration, cataracts, vision loss or photokeratitis (snow blindness).

Some contact lenses come with built-in tints that absorb harmful UV rays. Unlike sunglasses, these contact lenses completely filter UV rays, which are often reflected over the top or under the bottom of sunglass frames. These lenses absorb UV radiation without sacrificing brightness.

To protect their eyes, people with certain eye-health problems are often advised to wear ultraviolet-tinted lenses.

UV-tinted contact lenses are advisable for:

- vision correction after cataract surgery
- people on medications that increase light sensitivity, such as sulfonamides, tetracycline or oral contraceptives
- macular degeneration
- people who work outdoors
- skiers, snowboarders, mountaineers
- people active in water or beach sports
- people often exposed to UV-B rays at work, e.g., graphic artists, welders, electronics workers

Fun and fashion: painted contact lenses

Tinted contact lenses cover or enhance your natural eye color. All have a transparent central spot for clear vision. The colored part of contact lenses covers the eye’s iris (the colored part of the eye), not the pupil, so the tint does not affect the color of what you see. Tinted contact lenses are made for prescription and "plano" (purely cosmetic) wear.

Tinted soft contact lenses may be a better option than tinted rigid gas permeable (RGP) lenses, which are slightly smaller than the eye’s colored iris. Tinted contacts cost slightly more, but they have the same fitting needs, care regimens and health effects as normal contact lenses. You will need a thorough eye examination by an eye doctor (optometrist).

Enhancing or complementary tints add drama to existing eye color — make greens greener or tint them a slightly different shade. They come in a wide variety of hues, including aqua, blue, green, brown, amber and violet. These tints tend to look better on people with naturally light-colored eyes. People with a naturally dark-colored iris probably won’t notice much of a change in eye color.

Opaque tinted contact lenses cover the eye’s natural color. The eye takes on a completely different shade, e.g., a blue lens over a brown iris gives you blue eyes.

Painted contact lenses change your image. These contacts originated in the theater, where their striking designs and colors were custom-made as special-effects makeup for performers. Their look is startling: from white "ghost" eyes and red "wildfire" eyes to cats’ eyes and even billiard balls.

When caring for colored contacts, follow manufacturer’s instructions carefully, as hydrogen peroxide and chlorine cleaners can affect the lens color of RGP lenses.

Colored lenses do not affect night driving. The tints pose no danger of eye infection and do not change color perception.

One precaution: all contact lenses — whether clear, tinted or painted — are medical devices. Don’t wear someone else’s contacts. The shape of your eye and theirs could be radically different. Contact lenses that don’t fit correctly can damage your eyes.

For more information


Multifocal contacts. Visual Eyes, Nov 1998
Lenses and lifestyles. Visual Eyes, March 1998

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