Eye Health Library

Contact Lenses

Contact lenses free you from your glasses! They don't fog up in winter, or fall off during recreation activities, and provide excellent vision! Because contact lenses are inserted into the eye, they require more detailed design than a pair of spectacles. Contact lenses also require a higher level of care.

Some of the adverse responses to contact lenses do not produce symptoms, but may still harm the eye. For this reason, regularly schedule check-ups are recommended for all contact lens wearers.

Ask your optometrist if contacts are right for you!

Contacts For You?

The vast majority of people requiring vision correction can wear contact lenses without any problems. New materials and lens care technologies have made today's contacts more comfortable, safer and easier to wear. Consider the questions and answers below to help assess whether they're a choice you should consider.

Contact lens wear may be difficult if:

  • Your eyes are severely irritated by allergies;
  • You work in an environment with lots of dust and chemicals;
  • You have an overactive thyroid, uncontrolled diabetes, or severe arthritis in your hands; or
  • Your eyes are overly dry due to pregnancy or medications you are taking.

After a thorough eye examination, your suitability for contact lenses and the specific contact lens option that best meets your requirements will be determined.

What are the advantages of wearing contact lenses?

  • Many wearers feel that contact lenses show their eyes in a better light or don't like the appearance of eyeglasses.
  • Better vision correction due to the reduced obstruction from eyeglass frames.
  • They provide excellent peripheral vision.
  • No fogging up in warm rooms.
  • No splattering during rain showers.
  • Less hassle as they don't get in the way during sports and other recreational activities.

What are the disadvantages?

  • Contact lenses require getting used to. New soft lens wearers typically adjust to their lenses within a week. Rigid lenses generally require a somewhat longer adjustment period.
  • Except for some disposable varieties, almost all lenses require regular cleaning and disinfection, a process that, although requiring only a few minutes, is more than some people want to undertake. Some types of lenses increase your eyes' sensitivity to light.

What lifestyle do you lead? What kind of work do you do?

For those involved in sports and recreational activities, contact lenses offer a number of advantages. In addition to providing good peripheral vision, eliminating the problem of fogged or rain splattered lenses, and freeing you from worries about broken glasses, contact lenses also mean you can wear non-prescription protective eye wear. Looking sideways through the lenses of glasses leads to prismatic effects because you are not looking through their centers. Your eyes have to coordinate differently to cope with this. This does not happen with contact lenses because you always look through the centers of the lenses as they move with your eye movements.

Your occupation and work environment should also be taken into consideration. People whose work requires good peripheral vision may want to consider contacts. Those who work in dusty environments or where chemicals are in heavy use are likely to find spectacles more comfortable.

Do you like wearing glasses?

Do you like the way glasses feel? Do you like how you look in them? No longer is it really necessary to choose between either contacts or glasses. Some of today's contacts are so easy to wear that you can use them intermittently — for special occasions, while participating in sports or to match your fashions.

New single-use, one-day disposable lenses are comfortable and do not require cleaning. They may be easily interchanged with glasses.

How Contact Lenses Correct Vision

Contact lenses are designed to rest on the cornea, the clear outer surface of the eye. They are held in place mainly by adhering to the tear film that covers the front of the eye and, to a lesser extent, by pressure from the eyelids.

As the eyelid blinks, it glides over the surface of the contact lens and causes it to move slightly. This movement allows the tears to provide necessary lubrication to the cornea and helps flush away debris between the cornea and the contact lens.

Contact lenses are optical medical devices, primarily used to correct nearsightedness, farsightedness, astigmatism and presbyopia. In these conditions, light is not focused properly on the retina, the layer of nerve endings in the back of the eye that converts light to electrochemical impulses. When light is not focused properly on the retina, the result is blurred or imperfect vision.

When in place on the cornea, the contact lens functions as the initial optical element of the eye. The optics of the contact lens combine with the optics of the eye to properly focus light on the retina. The result is clear vision.

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Types of Contacts

Confused about contacts? Advances in contact lens technologies have created many options in addition to hard and soft lenses. Today, contact lenses are likely to be described in one or several of the following ways.

By their prescribed wearing period: The time that the lenses are left in the eyes.

  • Daily Wear (Up to 18 hours)
  • Extended Wear (For overnight use, up to seven days)

By their replacement schedule: The time interval for replacing lenses.

  • Planned - (Frequent replacement: 1 month, 1-2 weeks; daily disposable)
  • Unplanned, or Conventional Replacement - (No specific time schedule before lenses are replaced)

By the type of vision correction for which they are designed:

  • Spherical (For near- or farsightedness -- myopia or hypermetropia)
  • Toric (For astigmatism)
  • Bifocals (For presbyopia)

By the type of tint they have:

  • Tinted to improve handling only
  • Tinted to enhance your eye colour (For light-colour eyes)
  • Tinted to change your eye colour (Opaque tints for light or dark eyes)
  • Clear - without tints

Of course, contact lenses are also still described by the basic type of material of which they are made:

  • Soft (hydrophilic)
  • Rigid Gas Permeable

By Wearing Period

Daily Wear: Lenses prescribed for daily wear are to be worn only during waking hours, usually up to a maximum of 18 hours. Daily wear lenses are removed at night and cleaned and disinfected after each removal.

Extended Wear: Extended wear lenses may be worn on an overnight basis for up to seven consecutive days (six nights). You should wear your lenses on an extended wear basis only on the advice of your optometrist.

Extended wear lenses generally have a higher water content or thinner center thickness than other lenses and permit more oxygen to reach the eye. However, their use has been linked to a higher incidence of eye problems. Extended wear lenses need to be cleaned and disinfected at recommended intervals or discarded after use.

By Replacement Period

Contact lens are often prescribed with a specific replacement schedule suitable to your specific needs. Planned (or Frequent) Replacement contacts are disposed of and replaced with a new pair according to a planned schedule. Unplanned replacement lenses (often called conventional lenses) are not replaced according to a pre-determined schedule. They are typically used for as long as they remain undamaged, usually around 12 months for soft lenses.

Why replace lenses frequently?

Almost immediately after they are inserted, contact lenses begin attracting deposits of proteins and lipids. Accumulated deposits, even with routine lens care, begin to erode the performance of your contacts and create a situation that presents a greater risk to your eye health.

A specific replacement schedule helps to prevent problems before they might occur. Contact lens wearers, in turn, enjoy the added comfort, convenience and health benefits of a planned replacement program. Planned replacement lenses are generally a thinner design or are made of different, more fragile materials with a higher water content than unplanned replacement or conventional contact lenses.

Based on a complete assessment of your needs, a prescription for planned replacement lenses may call for replacement:

  • Quarterly,
  • Monthly
  • Every 1-2 weeks
  • Daily

Except for daily disposables, planned replacement lenses require cleaning and disinfection after each period of wear unless they are discarded immediately upon removal. Planned replacement lenses can be worn as daily wear -- removed before sleep -- or as extended wear, if recommended by your practitioner.

By Type of Vision Correction Required

Contact lenses may be identified by the type of refractive error they are designed to correct.

  • Spherical contact lenses for nearsightedness (myopia) and farsightedness (hypermetropia);
  • Toric contact lenses for astigmatism;
  • Bifocal lenses for presbyopia, the loss of ability to focus on reading or close-up activities.

As an alternative to special bifocal contact lenses, many practitioners use a system called monovision where one eye is fitted with a distance lens and the other with a reading lens. Approximately two-thirds of patients adapt to this type of contact lens wear.

By Type of Tint

Contact lenses may be described as clear or tinted. Tints are used to make lenses more visible during handling, or for therapeutic or cosmetic reasons. Tints can enhance eye colour, or change it altogether.

Three categories of tinted contact lenses are available.

  • Cosmetic enhancement tints are translucent and are designed to enhance your natural eye colour. They are best for light-coloured eyes (blues, greens, light hazel or grays). When wearing these tints, the colour of your eye is a blend of the lens tint and your natural eye colour and iris pattern.
  • Opaque or "cosmetic" tints change the colour of your eyes whether they are dark or light. The pattern on the lens, which is coloured, overlies the coloured part of your eye, resulting in a colour with a natural look.
  • Visibility tints are very pale, coloured just enough to make the contact lens visible while you are handling it. They usually have no effect on eye colour.
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Soft vs. RGP Lenses

Below is a brief comparison of Soft and Rigid Gas Permeable (RGP) contact lenses. A thorough eye examination and a better understanding of your specific vision requirements will help determine the best options for you.

Soft Contact Lenses

Advantages
  • Greater initial comfort than hard or rigid gas permeable (RGP) lenses.
  • Shorter adaptation period for new wearers.
  • Ideal for intermittent wear.
  • Less susceptible to the intrusion of foreign objects under the lens, such as dust.
  • Less sensitivity to light than with hard or RGP lenses.
  • Rarely fall out of the eye, making them ideal for sports, particularly contact sports such as football or basketball.
  • Available in tinted versions.
Disadvantages
  • Less durable than hard or RGP lenses.
  • May dry out, causing discomfort for some, especially under a hair dryer, in hot rooms, or in windy, dry weather.
  • More involved lens care, especially for conventional soft lenses.
  • Susceptible to more protein or lipid deposits, that reduce lens performance in the long term.
  • May absorb chemicals from the environment, which can cause irritation.

Rigid Gas Permeable (RGP) Lenses

RGP lenses are, as the name implies, rigid, but the plastics of which they are made are somewhat more flexible than hard lenses. Newer RGP lenses offer the advantage of allowing more oxygen to pass through to the eye. Sometimes they are referred to as "Oxygen Permeable Lenses". They are available in daily wear and extended wear options.

Advantages
  • Good vision.
  • Correct most corneal astigmatism.
  • Good durability.
  • Good handling characteristics.
  • Easier care.
Disadvantages
  • Less initial comfort than soft lenses.
  • Longer adaptation period required than soft lenses.
  • More easily dislodged.
  • Can scratch and break.
  • Intermittent wear less feasible.
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Presbyopia

As baby boomers reach middle age, the question looms large: How to avoid either of two telltale signs of aging -- bifocals or reading glasses?

Boomers have three contact lens options for correcting the close-up blurred vision that typically begins in middle age; a condition referred to as presbyopia. (One of the three options still calls for reading glasses, but they can be used discreetly.)

The three options are:

  • Bifocal contact lenses
  • Monovision
  • Contact lenses for distance vision with supplementary reading glasses slipped over the contacts for close work

Bifocal contact lenses

One of the two main categories of bifocal contact lenses may be suitable for you:

Simultaneous vision

With simultaneous vision bifocals, you look through both the reading and distance portions of the lenses all the time. This means that whenever you look at an object, you see two images of it. One will be clear (from the portion of the lens most matched to the distance at which you are observing). The other will be blurred (from the other portion of the lens). Your brain learns to ignore the blurred image so that you see the other clear image.

Translating

Translating bifocals are similar in concept to bifocal eyeglass lenses. They have a thicker lower edge, which, when you look down to read, rests on the lower lid. As your eye turns downward to read, it looks through the reading portion in the lower part of the lens. In fact, even though they "translate," a portion of vision through this type of bifocal is of the simultaneous type.

If you wear bifocal contact lenses, they will normally perform optimally in bright conditions. Because bifocal lenses divide the light into two images, each of which will use about half of the available light, you may find that, in dimly lit conditions, seeing is more difficult with bifocal contacts. Driving at night may present more difficulty, for example.

Monovision

Monovision is an option in which one eye is fitted with a lens for seeing things at a distance and the other eye is fitted for seeing close-up. After a period of adjustment, the brain switches to the eye that is giving the clearest image at the time.

While many people successfully use monovision, others find adapting difficult. Mildly blurred vision, dizziness, headaches and a feeling of slight imbalance may last for a few minutes or for several weeks as you adapt. Generally, the longer these symptoms last, the more unlikely it is that you will adapt successfully. Approximately two-thirds of patients eventually adapt to a monovision correction.

Adjusting to demanding conditions

If you are new to monovision you may benefit from avoiding visually demanding situations at first, and instead to wear their new lenses only in familiar situations. For example, it may be better to be a passenger, rather than a driver, in a car. In fact, you should only drive with monovision correction if you can pass your driver's license eye examination while wearing it.

Coping in special situations

Some people are uncomfortable in situations with low illumination, such as night driving. If that is your concern, ask us about prescribing an additional lens to correct both eyes for distance for those times when sharp distance vision is required. An alternative is a pair of glasses with additional power in the reading eye so that the combined power of your contacts and the spectacles match your distance prescription.

If you require very sharp near vision, you might want to ask about an additional lens to correct both eyes for close-up work. Or, to occasionally have the clearest vision for critical tasks, you may want to request supplemental glasses to wear over your monovision correction, converting the distance eye to a reading prescription so that you can use both eyes at near distance.

Contacts for distance; reading glasses for near vision

The final option for correcting presbyopia is this: Wear contact lenses for distance, then slip some reading glasses over them for close-up work. Perhaps not the perfect answer, this option enables you to avoid the dreaded bifocal glasses. And that can still be a definite plus.

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Wear & Care Tips

The information below is intended as a supplement to the training and instruction you receive as part of a contact lens fitting program.

How to insert your lenses

  • Wash your hands with a mild soap, rinse completely and dry with a lint-free towel. A wet finger may cause a soft lens to flatten. Avoid using fingernails to handle your lenses.
  • If you're working near a sink, close the drain.
  • Get in the habit of always working with the same (right or left) lens first to avoid mix-ups.
  • Pour the lens and storage fluid from the case into your palm.
  • Inspect the lens for particles, deposits or tears.
  • Place the lens, cup side up, on your dry forefinger. Determine if the lens is right side out. If it is right side out, the lens' edge will appear almost straight up. If inside out, the edges will flare out slightly. Another test is to place the lens on a crack in the palm of your hand and then cup the hand slightly. This will flex the lens. If the edge of the lens curls inwards, it is the correct way out; if the edge curls outwards and wraps onto the palm of the hand, it is inside out. If it is inside out, reverse it.
  • To Insert.
    • Hold the upper lashes (or lids) to prevent blinking.
    • Pull the bottom eyelid down using your middle finger.
    • Look up so the white part of your eye shows.
    • Place the lens onto the exposed white part of your eye.
    • Or, instead of looking up, look straight ahead at the lens and gently place it in the center of your eye.
    • Remove your finger and let go of the lids, bottom lid first, and then top.
  • Look downward to help position the lens, then close your eyes momentarily.
  • Apply one or two drops of lens lubricant (eye drops) if your lenses feel dry or if blurry vision occurs during wear.
  • Follow the same steps to insert the other lens.

How to remove your lenses

  • Wash and dry your hands and close any nearby drains.
  • With your head straight, look upwards as far as you can.
  • Place your middle finger on the lower eyelid of your right eye and pull the eyelid down, then touch the lower edge of the lens with the tip of your index finger.
  • While still looking up, slide the lens down to the white part of the eye with your index finger.
  • Still looking up and holding the lens under the index finger, move your thumb so that you can compress the lens lightly between the thumb and the index finger. Then gently remove the "folded up" lens from the eye.
  • If you have difficulty removing the lens, place a few comfort drops in the eye, wait moments and try again.
  • Remove the left lens following the same procedure.

Follow Professional advice

  • Wear your contacts only for the length of time recommended, even if they feel comfortable.
  • Remove, clean and disinfect your lenses at the intervals prescribed.
  • Have regular check-ups.
  • Don't sleep or nap while wearing your contacts unless specifically indicated.
  • Don't use any eye medications without consulting the doctor.
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Teens & Contacts

Oh, the pressure! Get great grades, excel in at least one sport, play a musical instrument, work part-time, hang out with friends -- and always, always look cool. If you're a teenager today, much is expected.

But what to do if suddenly you can't make out the writing on the blackboard, you can't see the ball until it's practically in your hands, or you have to squint to read the notes?

What to do -- and still look cool? Try contact lenses. Not that glasses can't be fashionable. But for today's active teenagers, contacts are a perfect fit. What your parents may not know is that today's lenses are more comfortable and easier to care for than those of a decade ago. Plus, there are more types of contacts, from disposables to toric (especially for people with astigmatism), from which to choose. In other words, there are almost certainly lenses to fit your individual needs.

When can you begin wearing contact lenses?

Even pre-teens can handle contacts. A three-year study* conducted by the Indiana University School of Optometry found children ages 11-13 able to handle contacts well and understand the use of their care systems to maintain clean, comfortable lenses. When to begin contact lens wear can only be determined in conjunction with your eye care practitioner.

What are the advantages of contact lenses over eyeglasses? Glasses can get in the way, especially in sports, cheerleading, dance or other exercise. Not contact lenses. Nor are there rims to interfere with your side, or peripheral, vision.

When you're active, contact lenses don't steam up or slide down your nose. Plus, they eliminate that annoying pressure behind your ears.

"Will Young Children Comply and Follow Instructions to Successfully Wear Soft Contact Lenses?" by P.S. Soni, D.G. Horner, L. Jimenenz, J. Ross, J. Rounds; CLAO Journal, April 1995.)

Fiction or fact? Truths about contact lenses

FICTION:
Teen eyes are not "mature enough" for contacts.
FACT:
Most eye care professionals agree that by age 13, even as early as age 11, most eyes are developed enough for contact lenses. An eye exam will confirm whether contacts can be worn or not.
FICTION:
Contacts fall out a lot.
FACT:
They fell out more often when the only ones available were hard lenses. Soft lenses conform to the shape of the eye, are larger in diameter and are tucked under the eyelids, so they usually don't move out of place or fall out. Plus, they're usually more stable than glasses, especially for sports.
FICTION:
Contact lenses are expensive.
FACT:
Not! The price of contact lenses is comparable to that of an average pair of eyeglasses.
FICTION:
Contact lenses are hard to care for.
FACT:
Not at all. Today's lens care systems are easy and quick to use. Contacts can be ready to wear in just five minutes.
FICTION:
Contact lenses are not safe to wear for sports.
FACT:
Except for water sports, contacts are very safe. They can't be broken or knocked off the face and they provide unobstructed peripheral vision.

Ask your parents to make an appointment to assess your ability to wear contacts. If he or she gives thumbs-up, then try a pair. Wearing lenses is the best way to find out if you and contact lenses were made for each other.

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Lens Care Solutions

When you are fitted for contact lenses a particular lens care system is recommended -- a group of products to clean, disinfect and make your lenses safe and comfortable for wear.

Since different systems use different types of chemicals, it is not advisable to mix or substitute solutions from other systems. Doing so could lead to discoloured lenses, eye discomfort or eye injury. In particular, rigid lens solutions should not be used to clean or disinfect soft lenses as the chemicals can damage the soft lens material.

Soft Contact Lens Care Systems

Regardless of how they are packaged, most lens care systems include products that perform six different functions. Some systems combine two or more functions into one product while others keep them separate. The functions required are dependent upon the type of lens regimen and your eyes and will be discussed with you as part of a contact lens training program.

The six different functions performed by soft lens care systems are:

Daily Cleaning to remove debris accumulated and adhering loosely to the lens. This debris, if not removed, can eventually make the lenses uncomfortable, interfere with vision and reduce the ability of the disinfecting solution to kill potentially harmful microorganisms. In addition, the cleaning solutions perform the first step in the disinfection process.

Disinfecting to kill growing forms of microorganisms (bacteria, fungi, and viruses) on the lenses.

Rinsing and Storing requires the use of an ophthalmic isotonic saline solution or may be performed with some types of disinfectant solution. Most saline solutions are not suitable for storage of lenses, as they do not contain anything to kill or prevent the growth of microorganisms.

Comfort or Lubricating Drops are used to provide refreshment for dry eyes, in conditions of low humidity or for added comfort near the end of the wearing day.

Protein Removal removes stubborn protein deposits and, with daily cleaning and disinfection, helps restore a clean, fresh contact lens surface. Protein removal is generally not required for planned replacement lenses, which are replaced before the deposits can cause difficulties.

Rigid Gas Permeable (RGP) Contact Lens Care Systems

RGP lenses must be cleaned and disinfected for safe and comfortable wear. The lens care system recommended will include a group of products designed to work together to clean, rinse, disinfect and remove protein deposits and to re-wet your eyes if they become dry during contact lens wear.

It is important to use only those systems designed specifically for rigid gas permeable lenses. They are formulated with disinfectants and preservatives proven to work best with the material of which your lenses are made.

If you wish to change your lens care regimen or to try a new lens care product, it is best to discuss this first, even if only by telephone, to ensure that you select products that are compatible with your eyes and will work well.

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Coloured Contacts

Contact lenses aren't just for seeing better. They're for looking better too. In fact, some people who don't even need vision correction wear tinted contact lenses as a way to change their look.

Today's tinted lenses allow you to enhance your natural eye colour -- making the blue bluer or the green greener -- or change it altogether.

Three categories of tinted contact lenses are available:

  • Cosmetic enhancement tints are designed to enhance your natural eye colour. These translucent lenses are best for light-coloured eyes (blues and greens, hazels and grays). When wearing these tints, the colour of your eye becomes a blend of the lens tint and your natural eye colour.
  • Opaque, or "cosmetic," tints change the colour of dark eyes. The pattern on the lens, which is coloured, overlies the coloured part of your eye. The result is a natural look.
  • Visibility tints are very pale, but are coloured enough to make the contact lens visible during handling without any effect on eye colour.

With tinted lenses you accomplish two goals at once: Seeing better and looking better.

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