With a contact lens prescription in hand, it's possible to buy your contact lenses from stores, the Internet, over the phone, or by mail. There are 75 million contact lens wearers worldwide and 31 million in the U.S. alone. All correcting contact lenses must have a valid prescription from an ophthalmologist or optometrist.

The choice of which lens is right for you should be based only on an examination by your doctor or eye care professional, not over the phone. Contact lens sales are regulated by the FDA (Food and Drug Administration) and the FTC (Federal Trade Commission.)

The expiration date for your prescription is currently set by your state requiring a one-year or two-year renewal; if your state hasn't set a minimum expiration date, government regulation sets a one-year date unless your eye doctor determines there's a medical reason for less than one year. Extended wear lenses are usually soft contact lenses; made of flexible plastics that allow oxygen to pass through to the cornea. People who have good distance vision but need help for reading can get a monovision reading lens for one eye.

In some models, each lens corrects for near and distance vision and in others, one lens is for near vision, and the other is for distance. Soft lenses also come as disposable products, that is, used once and discarded, or as planned-replacement lenses. While the ability to hold water increases the oxygen permeability of soft lenses, it increases their fragility quotient as well.

Rigid gas permeable contact lenses are more durable, resistant to deposit buildup, and generally give a clearer, crisper vision. Although easier to handle and less likely to tear, rigid gas permeable lenses are not as comfortable initially as soft contacts and it may take a few weeks to get used to wearing the RGPs, compared to just a few days for soft contacts. If you plan to wear lenses for more than 18 hours for the purpose of eye color change, then buy colored soft lenses.

Bifocal correction is possible with both soft and rigid lenses. Rigid gas permeable lenses tend to be less expensive over the life of the lens since they last longer than soft lenses.

Rebates may be available from the seller, from the manufacturer, for first-time contact lens wearers and for individuals who buy lenses and get an eye exam. When you place your contact lens order, request the manufacturer's written patient information for your contact lenses; it'll give you important risk and benefit information as well as instructions for use. When you receive your order, if you think you've received an incorrect contact lens, check with your doctor or eye care professional right away; don't accept any substitution unless your eye care professional approves it.

Check out how long the online supplier has been in business before you buy. Ask about prices at your doctor's office when you have your eye examination, or during a follow-up visit after you get your prescription. Focus on value, not just the price; most people looking for the best price are really looking for the best value.

You can buy contact lenses from an eye doctor, on the Internet, from an optical store or a warehouse club. Buy your contact lenses from a supplier you're familiar with and know is reliable or has name familiarity. When you place your order make sure your lenses are available and not out of stock, because you'll need them now.

Don't wear lenses any longer than they're prescribed for, nor when sleeping unless you are otherwise directed. Basic rule: never swap your contact lenses with anyone else. When the eyes are open, tears carry adequate oxygen to the cornea to keep it healthy, but during sleep, the eye produces fewer tears, causing the cornea to swell.

One sight-threatening concern is the infection Acanthamoeba keratitis, which is caused by improper lens care; this difficult-to-treat parasitic infection's symptoms are similar to those of corneal ulcers. Be aware that extended-wear (overnight) contact lenses - rigid or soft - increase the risk of corneal ulcers, which are infection-caused eruptions on the cornea that can lead to blindness; symptoms include vision changes, eye redness, eye discomfort or pain, and excessive tearing. The use of homemade saline made by using salt tablets mixed in water is one of the biggest contributors to Acanthamoeba keratitis in contact lens wearers: the FDA no longer condones the use of salt tablets.

If you lead an active lifestyle, contact lenses can provide you with close to natural vision. Make sure to visit a reputable eye doctor for a complete eye examination once a year, or more frequently if needed. If you prefer the way you look without glasses or find glasses to be cumbersome and awkward, contacts can provide the ease, convenience and comfort you need.