Contact lenses can effectively correct the three main eye disorders: farsightedness, nearsightedness and astigmatism.
Approximately 20 percent of the American adult population who require some type of vision correction wear contact lenses. The use of contact lenses can provide accurate correction of vision disorders without the need for refractive eye surgery. Contact lenses are particularly useful when participating in sports as they give the wearer an unobstructed field of vision.
Contact lenses have actually existed for over a hundred years. In that time span, major advancements have made it so almost everybody can wear contact lenses successfully. Previously, your eye doctor may have said that you were not a good candidate for contact lenses, or you may have experienced problems when you tried to wear them. Today, this may is longer the case as there are far more convenient contact lens types than there were in the past.
If you have never worn contact lenses before, the very first thing you need to do is to make an appointment with an eye doctor. In the U.S., contact lenses require a prescription and must be fitted properly by an eye care professional. Your doctor will determine your specific visual needs, the structure of your eyes as well as your tear production. These determinations help decide the best kind of contact lenses for you to wear comfortably.
Many different types of contact lenses are available on the market today. They can be categorized according to:
- Wearing time
- Frequency of disposal
- Lens design
- Additional features
There are three types of contact lens materials: soft lenses, GP lenses, and hard lenses. Accounting for over 65% percent of new contact fittings, soft hydrogel contact lenses are the most popular lenses purchased in the U.S.
- Soft Lenses: Made from water containing gel-like plastic known as hydrogel, soft lenses completely cover your cornea. An advanced soft lens type, which transmits more oxygen to the eye than regular soft lenses do, is called silicone hydrogel contact lenses.
- GP Lenses: These are also called “oxygen permeable” lenses. Made from a waterless, rigid type of plastic, these lenses are particularly suited for those who have a high degree of astigmatism or presbyopia, an age related condition where the lens does not change shape as easily. Smaller in diameter, GP lenses typically give sharper vision than soft lenses.
- Hard Lenses: Comprised of a rigid, plastic material, hard lenses do not transmit oxygen to the eyes. Therefore, they are very rarely prescribed anymore.
Prior to 1979, all contact lens wearers had to remove and clean their lenses every night before going to bed. Eventually, “extended wear” contacts allowed wearers to sleep with their contacts still in their eyes. Today, thee lens types are categorized according to wearing time: daily wear, extended wear and continuous wear.
- Daily Wear: These have to be taken out before bedtime.
- Extended Wear: This type allows for overnight wear, generally for seven consecutive days before removal is necessary.
- Continuous Wear: This describes lenses that can be worn for thirty consecutive days. This is the maximum wearing time that is given FDA approval.
Frequency of Disposal
Even with appropriate care, contact lenses need to be replaced on a frequent basis to avoid eventual build-up of deposits and contamination of the lenses. These two factors greatly increase the chances of eye infections. Soft lenses are generally classified according to how often they need changed.
- Daily Disposable Lenses: Replace after wearing for one day.
- Disposable Lenses: Replace after two weeks of wear or even sooner.
- Frequent Replacement Lenses: Replace monthly or every three months.
- Traditional (Reusable) Lenses: Replace after six months or perhaps longer.
Various designs of lenses correct different kinds of vision problems. All contacts can be custom made to satisfy your individual needs. Several other lens designs are also available but are used for less common eye conditions like keratoconus, an eye disorder where the cornea cannot maintain its rounded shape. The four main lens designs include spherical, bifocal, orthokeratology and toric.
- Spherical: These lenses are the common rounded lenses that effectively correct farsightedness (hyperopia) or nearsightedness (myopia).
- Bifocal: These contacts have different areas for far and near vision to correct presbyopia.
- Orthokeratology: Specifically designed to reshape your cornea while sleeping, these lenses permit you to go without contacts during the day.
- Toric: This type of contact lenses corrects astigmatism in addition to hyperopia and myopia.
Dry Eye Contacts: Some people find that there eyes are particularly dry, and wearing contacts is uncomfortable for them. Some soft contact lenses are specifically designed to diminish the chances of dry eye symptoms related to contact lens wear.
Colored Lenses: The majority of the contacts listed above come in various colors to enhance the color of your eyes or to totally change your natural eye color.
Special Effect Lenses: Special effect contacts take color an additional step to achieve theatrical or novelty effects.
Prosthetic Lenses: Different colored lenses can be utilized for medically required reasons. Prosthetic contacts are opaque soft contacts which can be custom made for an eye that has been disfigured as a result of disease or injury. As much as possible, they are designed to match the appearance of the unaffected eye.
Custom Made Lenses: When conventional contacts do not work, you may be an excellent candidate for contacts that are made-to-order for your individual vision needs.
UV-inhibiting Lenses: Certain soft lenses help shield your eyes from the sun’s harmful ultraviolet (UV) rays. These rays can lead to the formation of cataracts and other eye issues. One still needs to wear UV inhibiting sunglasses outside for optimum sun protection as contacts do not cover the entire eye surface.
Scleral Lenses: These are designed especially to treat presbyopia, keratoconus and other irregularities of the cornea. They are large diameter gas permeable contact lenses.
How to Determine Your Contact Lens Type
Your eye care professional can help determine visual deficits, your eye’s physiology and which type of lens best suits you. Some important considerations for determining your contact lens type include:
- Vision: Your contacts must give you good eyesight by effectively correcting your vision condition.
- Fit: The lenses must fit your eyes correctly. Not every brand of lens comes in every combination of curvature and diameter.
- Health Status: Certain medical conditions may determine your contact choice, such as dry eyes.
- Desired Features: You may have contact lens features you prefer, such as overnight wear or a certain color.
Contact Lens Care and Wear
The cleaning, disinfecting and storage of contact lenses is much easier than it was in the past. Even a few short years ago, several bottles of cleaning solutions and enzyme tablets were needed for proper lens care. “Multipurpose” products are now available that clean, disinfect and store contact lenses. If desired, you can forego lens care completely by using disposables that are changed each day.
Contact Lens Problems
A certain amount of “trial and error” could be necessary to discover the perfect lenses for all your specifications. Individuals can react differently to cleaning solutions and varying lens materials. In addition, factors such as diameter, curvature and power can only be completely finalized until you have worn your lenses for a period of time. This is particularly the case for more complex fits, such as bifocals or toric lenses designed especially for astigmatism.
As mentioned, many contact lens choices are available to give you optimal comfort and good, healthy eyesight. If your contacts and eyes are uncomfortable, or you are having problems seeing properly, you should take your lenses out and visit your eye care provider. The doctor will be able to determine the cause and correct the problem. A slight adjustment or change of lenses may be all that is necessary.
Purchasing Contact Lenses
Once you and your eye care provider have mutually agreed on the correct lenses to meet your needs, you will be able to buy a supply of lenses either from the ophthalmologist or from a retail outlet or online source. Some contact lens retailers offer better value and prices on new and replacement lenses than others. You will likely have to shop around a bit to find the best deal.
WebMD (2009). Contact Lenses. Retrieved on May 20, 2013 from:
Weinstock, F.J. (2013). Contact Lenses. Retrieved on May 20, 2013 from: http://www.emedicinehealth.com/contact_lenses/article_em.htm