Contact lenses

Millions of people around the world wear contact lenses–more than 24 million in the United States alone.

Depending on your lifestyle, your motivation and the health of your eyes, contact lenses may provide a safe and effective alternative to eyeglasses when used with proper care and maintenance.

What are contact lenses?

Contacts are thin, clear disks of plastic that float on the tear film that coats the cornea, the curved front surface of the eye. The health of the corneal surface and tear film are very important to your comfort and the clarity of your vision when you are wearing contacts.

Contact lenses are used to correct the same conditions that eyeglasses correct :

• myopia (nearsightedness);
• hyperopia (farsightedness);
• astigmatism;
• presbyopia.

What are the different types of contact lenses?

Many different plastics are used in the manufacture of contact lenses, but basically there are two general types of lenses: hard and soft.

Hard lenses include the PMMA contacts that were first developed in the 1960s but are rarely used today; and rigid gas–permeable, or RGP, contacts. RGP contacts combine plastics with other materials such as silicone or fluoropoly–mers to produce a lens that holds its shape, yet allows the free flow of oxygen through the lens to the cornea. These lenses are more "wettable," easier to adjust to and more comfortable to wear than the old PMMA hard lenses.

RGP lenses may be the best choice when the cornea has enough astigmatism (is shaped like an egg instead of an orange) that a soft lens will not provide sharp vision. They may also be preferable when a person has allergies or tends to form protein deposits on his or her contacts.

• Soft lenses are the choice of most contact lens wearers for their comfort as well as for the great number of options available in soft contacts. These options include:

• daily wear. These lenses are the least expensive, are removed nightly and are replaced on an individualized schedule. They should not be used as an extendedwear lens.

• extended wear. These lenses are worn overnight but are removed at least weekly for thorough cleaning and disinfection. They are being recommended less frequently, since there is a greater risk of corneal infection with any overnight wear of contact lenses.

• disposable wear. These lenses are more expensive, but convenient. They are removed nightly and replaced on a daily, weekly or monthly basis. Disposable lenses are sometimes recommended for people with allergies and for those who tend to form deposits on their lenses. Colored and toric lenses can be disposable as well.

• colored contacts. These lenses can change the appearance of your eye color to varying degrees.

• toric contacts. These lenses can correct astigmatism, although sometimes not as well as RGP lenses. They usually cost more than other contact lenses.

As one ages, correction for near vision is often necessary because the lens of the eye can't change shape as easily as it once did. This common condition, called presbyopia, can be corrected in one of three ways:

• wear your distance correction in the contacts, and wear reading glasses when needed;

• wear one contact for distance vision, and one for near vision. This option is called "monovision," and it works well for many people but not for everyone. You may need a trial period to decide if monovision is for you;

• wear bifocal contacts, which are designed to allow both distance and near vision. These lenses are somewhat more expensive to fit and may not provide satisfactory vision for all people.

Special uses for contact lenses include "bandage" lenses, to cover the corneal surface and provide comfort after injury or surgery; lenses for infants; RGP lenses, for people with very irregular corneas due to injury or disease; and painted contact lenses, to change appearance or reduce glare after eye trauma.

What does the price of contact lenses include?

When comparing the price of contact lenses, it is important to consider what services are included. Does the fitting include a complete eye examination and follow–up? Can you exchange lenses during the initial fitting, and is insurance for lost lenses available?

If you need treatment for an eye condition not directly related to the contact lenses, such as inflamed eyelids or dry eyes, there may be additional charges.

What are the risks of wearing contact lenses?

Lenses that are not properly cleaned and disinfected increase the risk of eye infection. Lenses that are old or not properly fitted may scratch the eye or induce blood vessels to grow into the cornea. Because a lens can warp over time, and the cornea can change shape, the fit of the contact lens and the power should be re–evaluated on a regular basis. Your return visits will be scheduled depending on the condition of your eyes and visual needs.

Any eyedrops can interact with all types of contact lenses. It is best to avoid the use of eyedrops while wearing lenses, except for wetting drops recommended by your eye doctor.

What is proper care of contact lenses?

Any lens that is removed from the eye needs to be cleaned and disinfected before it is reinserted. Your doctor will discuss the best type of cleansing system for you, depending on the type of lens you use, any allergies you might have and whether or not your eye tends to form protein deposits.

Care of contact lenses includes cleaning their case, since it is a potential source of infection. The case should be rinsed with water, wiped and allowed to dry.

Daily wear lenses should not be worn while sleeping.

Homemade saline (salt water) solutions have been linked to serious corneal infections and should not be used.

Who should not wear contact lenses?

You may not be a good candidate for contacts if you have :

• frequent eye infections;
• severe allergies;
• dry eye that is resistant to treatment;
• a very dusty work environment;
• an inability to handle and care for the lenses.

Are contacts for you?

Choose an eye care professional who is experienced with contact lenses and with whom you can discuss your needs and expectations. Your eye care professional should diagnose and treat any eye problems that may hinder healthy lens wear and be able to correct problems that arise during lens wear.

You should examine your own motivation for wanting contacts and your commit–ment to the care and timely replacement of contacts for the optimal health of your eyes.