Contact Lenses

What Are Contact Lenses?

Contact lenses were invented more than 100 years ago as an alternative to eye glasses. Though they were originally made from glass and later hard plastic, contact lenses today are made from soft plastic. They are small, thin disks specially designed to be placed directly onto the surface or cornea of the eye. While they are most commonly used to correct vision problems such as nearsightedness, farsightedness and astigmatism, they may also be used to treat certain eye conditions and diseases. For example, contacts often are used by individuals who have had cataract surgery but did not receive lens implants.

Can anyone wear contact lenses?

While not everyone who wears glasses wants to wear contacts, nearly 90 percent of those wishing to wear them can be accommodated. Contact lenses may not be appropriate, however, for persons who experience repeated eye infections, suffer from allergic reactions, do not produce sufficient or appropriate lubrication, or who are exposed to extraordinary amount of dust, dirt or smoke. Persons who have specific vision problems or require special lenses may not be able to wear contacts.

What Are the Different Types of Contact Lenses?

There are two primary types of contact lenses: hard and soft. Hard contact lenses come in two forms: non-gas permeable and gas permeable. Gas-permeable lenses allow oxygen to reach the corneal surface, are more flexible than the non-gas permeable lenses, and are the most commonly used form of hard contacts.

Soft contact lenses also come in two forms: daily wear and extended wear. Both lenses are made from thin, flexible, plastic material. The daily-wear lenses require daily removal, cleaning and storage. Extended-wear lenses are designed to be worn overnight; however recent studies say extended-wear lenses should be worn for the shortest practical period, ideally for one day, because of the increased risk of infection associated with these lenses. This recommendation eliminates overnight wear.

What are the advantages and disadvantages of each lens?

Non-gas permeable hard lenses offer crisp vision, have a life span of up to 10 years, can correct major vision problems, are available in bifocal, and are relatively inexpensive. However, non-gas permeable lenses require longer adjustment periods, are less comfortable than soft contact lenses, may not be worn for extended periods of time (more than 12 hours), and should not be worn during vigorous physical activity such as sports because they can fall out more easily.

Gas-permeable hard lenses offer many of the same advantages as non-gas permeable lenses, as well as provide greater comfort since they permit oxygen to pass through the lens to the cornea of the eye. They also may be worn for longer periods of time and require minimal care, but they have a slightly shorter life span (five years). Similar to the non-gas permeable lens, gas-permeable lenses should not be worn during vigorous physical activity.

Daily-wear soft lenses provide the maximum amount of comfort and require a brief adjustment period. Soft lenses are pliable, absorb significant amounts of water, and permit oxygen to pass through the lens to the cornea of the eye. Soft lenses may be worn for more hours during the day, are easy to remove and insert, may be worn during vigorous physical activity, and are available in tinted colors. However, soft lenses are more expensive than hard lenses, may not offer crisp vision, cannot correct a severe astigmatism, require special care, are easily torn and have a much shorter life span (one or two years).

Extended-wear soft lenses offer the same advantages as the daily-wear lenses. These lenses may be worn for an extended period up to seven days by persons who have conditions that make frequent insertion and removal of contact lenses difficult. However, due to the risk of infection associated with extended use, daily removal and cleaning is recommended.

What’s the adjustment period?

The adjustment period varies depending on the type of lens and the individual. Hard contact lenses usually require several weeks to two months before they can be worn comfortably for any length of time. Soft contact lenses usually only require several days to a week. Initially, contact wearers may experience some irritation, redness, tearing, sensitivity to light and some occasional blurred vision. Persons with dry eyes may experience greater difficulty in adjusting to and wearing contact lenses, and may be at greater risk of eye damage.

What is the Proper Method of Caring for Contact Lenses?

Appropriate care and cleaning of contact lenses varies depending on the type of lenses. All lenses require regular, thorough cleaning and storing. It is especially important that daily-wear and extended-wear users follow the recommended regimen of lens cleaning, rinsing, disinfecting, enzymatic cleaning and lens case cleaning. With all lenses, only commercially prepared sterile solutions are recommended. Self prepared salt solutions are dangerous and should never be used. Your eye care professional can provide information and instructions regarding the most effective method for caring for your contact lenses.

Are there any risks involved?

Any time a foreign object or material is placed in the eye there is an increased risk of problems. It is important that you carefully follow the instructions of your eye care professional regarding care and cleaning of your lenses. If you experience any of the following problems, remove your lenses and contact your eye care practitioner:

• unexplained eye discomfort or pain
• redness of the eye
• watering eyes
• vision change

If not quickly diagnosed and treated, many of these problems may lead to serious eye diseases and infections that may result in permanent damage or vision loss. Most of these problems can be avoided with proper and thorough care as prescribed by your eye care professional.