Contact lenses for adults
Are contact lenses right for me?
Many people requiring vision correction can wear contact lenses without any problems or complications. New materials and lens care technologies have made today’s contact lenses more comfortable, safer and easier to wear. Consider the following to help assess whether they’re a choice you might consider.
How do 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, covering the front of the eye. As a secondary measure, they stay in place 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 myopia, hyperopia, astigmatism and presbyopia. These conditions prevent an image from focusing properly on the retina, the thin layer of tissue that lines the inner posterior portion of the eye. It consists of fine cells called photoreceptors, or rods and cones. These cells transmit light from the eye to the brain where it is perceived as vision. 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 source of vision. 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.
Would you like an alternative to wearing glasses?
Are there special occasions when you would prefer not to wear glasses? Contact lenses can be used irregularly for special occasions, while participating in sports or to match your fashion style. Single-use, daily disposable contact lenses are comfortable and easy to use. They do not require cleaning, you simply throw them away after each use.
Contact lens wear may not be recommended if:
• Your eyes are severely irritated due to ocular allergies.
• You work in an environment with lots of dust and chemicals.
• You have an overactive thyroid, uncontrolled diabetes, or severe arthritis in your hand.
• Your eyes are overly dry due to a medical condition, pregnancy or medications you are taking.
After a thorough eye examination performed by your optometrist, your suitability for contact lenses and the specific contact lens options will be determined.
What are the advantages of wearing contact lenses?
• Wearing contact lenses allows people to see your eyes better. Some people don’t like their appearance in eyeglasses.
• Contact lenses may allow better vision correction due to the reduced obstruction from eyeglass frames.
• They provide excellent peripheral vision.
• They don’t fog up.
• They don’t get in the way during sports and other recreational activities.
What are the disadvantages?
• Contact lenses require adaptations. New soft lens wearers typically adjust to their lenses within a week. Rigid lenses generally require a longer adjustment period.
• Except for some daily disposable varieties, almost all lenses require regular cleaning and disinfection. Although contacts only require a few minutes a day, it is more than some people are willing to undertake.
• Contact lenses have to be inserted and removed on a daily basis.
Your optometrist will need to know:
What kind of lifestyle you lead?
For those involved in sports and recreational activities, contact lenses offer a number of advantages. In addition to:
• Provides good peripheral vision, contact lenses
• Eliminates the problem of foggy or rain splattered lenses
• Frees you from worries about broken glasses
• Allows you to wear non-prescription protective eyewear
What kind of work do you do?
People whose work requires good peripheral vision may want to consider contacts. Looking sideways through the lenses of glasses leads to unnatural vision because you are not looking through their optical centers. Your eyes have to coordinate differently to cope with this. This does not happen with contact lenses because you always look through the optical center of the lenses as they move with your eye movements.
Those who work in dusty environments or where chemicals are in heavy use are likely to find spectacles more comfortable and safer.
Types of Contact Lenses
Contact lenses are a practical option for active people, athletes, and those who prefer the freedom from eyeglasses. Your optometrist has the training and qualifications to specify the proper lens material, fitting design, and care regime that will work best for your eye condition and lifestyle. Contact lenses are generally described by their wearing period, replacement schedule, correction style or tint.
By wearing period:
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, cleaned and disinfected after each removal.
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 and discarded after the predetermined use period.
By replacement period:
Contact lenses are often prescribed with a specific replacement suited to your needs and the design of the contact lenses.
Planned (or frequent) replacement contacts are disposed and replaced with a new pair according to a planned schedule, usually daily, biweekly or monthly.
Unplanned replacement lenses (often called conventional lenses) are not replaced according to a predetermined schedule. They are typically used for as long as they remain undamaged, but should be replaced every 12 months. These lenses are used less frequently and are usually reserved for special circumstances.
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 contact lenses and creates greater risk to your eye health.
A specific replacement schedule helps 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 generally have a higher water content or thinner center thickness than other lenses and permit more oxygen to reach the eye. They are less protein and lipid resistant, and need to be replaced more frequently as they become dirty more easily. Based on a complete assessment of your needs, a prescription for planned replacement lenses may call for replacement:
• Biweekly (2 weeks)
Except for daily disposable (they are discarded immediately upon removal), planned replacement lenses require cleaning and disinfection after each period of wear. Planned replacement lenses can be worn as daily wear (removed before sleep) or as extended wear (only when recommended by your optometrist).
By type of vision correction required:
Contact lenses may be identified by the type of refractive error they are designed to correct. There are three main types of contact lenses:
• Spherical contact lenses for nearsightedness (myopia) and farsightedness (hyperopia)
• Toric contact lenses for astigmatism
• Multifocal lenses for presbyopia (the loss of ability to focus on reading or close-up activities).
As an alternative to multifocal contact lenses for presbyopia, some practitioners use a system called monovision. This is where one eye, (the patient’s dominant eye) is fitted with a distance lens and the other eye, (the non-dominant eye) is fitted with a reading lens. Your eye care practitioner will identify which contact lens type is best for you and your needs.
By type of tint or colour:
Contact lenses may either be clear or tinted. Tints are used to make lenses more visible during handling, or for therapeutic or cosmetic reasons. Tints can also enhance or change eye colour. Three categories of tinted contact lenses are available:
• Cosmetic enhancement tints. These are translucent and designed to enhance your natural eye colour. They are best for light-coloured eyes (blue, green, light hazel or gray). When wearing these tints, the colour of your eye becomes a blend of the lens tint, your natural eye colour and iris pattern.
• Opaque or cosmetic tints. These lenses change the apparent colour of your eyes whether they are dark or light. The pattern on the lens, which is coloured, covers the coloured part of your eye (the iris), resulting in an eye colour with a natural look.
• Visibility or handling tints. These lenses are pale and coloured just enough to make the contact lens visible while you are handling it. They usually have no effect on eye colour and are often a pale blue or green.
Cosmetic contact lenses (coloured contact lenses)
Your optometrist has the training and qualifications to choose the proper contact lens material, fitting design, and care regime that works best for your eyes. Although contact lenses are mainly used for seeing better, tinted cosmetic lenses allow you to enhance your natural eye colour. Three categories of cosmetic (or coloured) contact lenses are available:
These are translucent and designed to enhance your natural eye colour. When wearing these tints, the lens tint and your natural eye colour blend together. These contacts usually work best with lighter-coloured eyes such as:
• Light hazel
These have a more solid pattern to cover the iris (the coloured part of the front of the eye), changing its apparent colour, whether they are dark or light.
Visibility or handling tints
These lenses are very pale and coloured just enough to make the contact lens visible while you are handling it. They usually have no effect on eye colour and are often a pale blue or green.
With tinted lenses you accomplish two goals at once: seeing better and achieving a specific look.
Remember that all contact lenses sold in Canada, whether used for vision correction or cosmetic reasons, are medical devices that must meet Health Canada’s safety, quality and labelling standards. Cosmetic contact lenses that do not correct eyesight have the same risks to eye health as prescription contact lenses if improperly fitted or used. The most serious complication is a corneal ulcer, which can lead to permanent vision loss.
If you are interested in enhancing or changing your eye colour, see your optometrist for a contact lens exam and any recommended follow-ups. This will determine your eligibility for contact lenses and which ones are most appropriate for you.
Contact Lens Solutions
There is a large amount of contact lens solutions in the market. The problem with selecting a random product is that all solutions react differently on the contact lens material, leaving the patient susceptible to eye irritation or, in rare cases, corneal ulcers.
All the contact lens solutions on the market today are very effective at killing bacteria and other pathogens on contact lenses. However, some brands of solutions are much better suited for a particular type of contact lens.
An optometrist will assess the compatibility of a contact lens on a patient’s eye by examining the corneal staining pattern (mild abrasions) with a biomicroscope. If a patient has a high percentage of corneal staining, then they typically would experience an increase in lens awareness and irritation. This leaves the individual more open to infection or inflammation. The chance of developing a corneal ulcer also increases.
Research shows some contact lens solutions can cause degrees of corneal staining depending on the contact lens brand. These findings stress the importance of using the correct brand of contact lens solution recommended by your optometrist.
Of particular concern is the use of private label solutions supplied by larger Big Box chain stores. They typically have more compatibility issues. The incompatibility of contact lenses with solutions could potentially lead to a toxic reaction, commonly caused by the preservative in the solution. When this occurs, alternative contact lens solutions or daily disposable contact lenses should be considered. Toxic reactions can also occur by using expired contact lens solution. It is always best to talk with your optometrist and ensure your contact lens solution is suitable for use with your contact lens brand.
Wear & Care for Contact Lenses
The information below is intended as a supplement to the training and instruction you receive from your optometrist as part of a contact lens fitting program. As part of the program, your optometrist will make several recommendations. This may include:
• Wearing your contacts only for the length of time recommended, even if they feel comfortable.
• Removing, cleaning and disinfecting your lenses at the intervals prescribed.
• Only using the cleaning and disinfecting system prescribed by your optometrist.
• Having regular eye examinations.
• Not sleeping or napping while wearing your contacts unless specifically indicated.
• Not using any eye medications or eye drops without consulting your optometrist.
How to insert and remove soft contact lenses
Soft versus 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 your optometrist determine the best options for you.
Soft Contact Lenses
Soft contact lenses are made of flexible plastic polymers. When fitted properly, they form to the cornea (the front surface of the eye). They are the most common type of contact lens worn.
• Greater initial comfort
• Shorter adaptation period for new wearers
• Ideal for non-continuous wear.
• Less susceptible to foreign objects (e.g. dust) getting under the lens.
• Less sensitivity to light.
• Rarely fall out of the eye, making them ideal for sports (e.g. football and basketball).
• Available in tinted versions.
• Flexible wear schedules (i.e. daily disposables that eliminate the need for lens cleaning all together).
• Not as durable as RGP lenses.
• May dry out, causing discomfort for some, especially for those in offices with forced air circulating, in hot rooms or in windy, dry weather.
• Susceptible to more protein or lipid deposits. This reduces long-term lens performance.
• May absorb chemicals (e.g. chlorine) from the environment, which can cause irritation.
Rigid Gas Permeable Lenses
Rigid Gas Permeable (RGP) lenses have been around since the 1960s. Newer RGP lenses offer the advantage of allowing more oxygen to pass through to the eye. They are often referred to as oxygen permeable lenses and are available in daily wear and extended wear options.
• Clear, crisp vision
• Good at correcting astigmatism
• Good durability
• Easier to handle
• Less initial comfort than soft lenses
• Longer adaptation period required
• More easily dislodged
• More susceptible to foreign objects (e.g. dust) getting under the lens
• Can scratch and break
• Flexible wear schedule is less feasible because re-adaptation is required if a person takes an extended break from use
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