Ophthalmologists (M.D. or D.O.) are eye surgeons who study and treat eye diseases and can also perform the duties of optometrists; optometrists (O.D.) examine eyes, diagnose and treat vision problems, and prescribe eyeglasses and contact lenses and in most states they also can prescribe medicine; opticians grind and dispense eyeglasses and in some states dispense contact lenses. 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. Among the many kinds of contact lenses you can buy are: novelty, colored, crazy, Halloween, special effects, theatrical, costume, scary, glow in the dark, wild eyes, mirrored, black, white, and red.

All correcting contact lenses must have a valid prescription from an ophthalmologist or optometrist. Be careful about buying cheap contact lenses, they may not be the quality you want; discounted quality contact lenses are the most desirable.

Soft lenses also come as disposable products, that is, used once and discarded, or as planned-replacement lenses. Extended wear contact lenses are used for overnight or continuous wear ranging from one to six nights or up to 30 days. Soft contact lenses are made of soft, flexible plastics that allow for oxygen to pass through to the cornea.

There are two general categories of contact lenses - soft and rigid gas permeable. The length of continuous lens wear depends on the lens type and your doctor's evaluation of your tolerance for overnight wear. Some doctors prescribe disposables as planned-replacement lenses, which are removed, disinfected, and reused before being discarded.

Newer soft lens materials include silicone-hydrogels to provide more oxygen to your eyes. 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. Extra-thin soft lenses are on the market for very sensitive people.

While the ability to hold water increases the oxygen permeability of soft lenses, it increases their fragility quotient as well. People who have good distance vision but need help for reading can get a monovision reading lens for one eye.

Check out how long the online supplier has been in business before you buy. Beware of attempts to substitute a brand different from the one you want when buying contacts. 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.

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. You can buy contact lenses from an eye doctor, on the Internet, from an optical store or a warehouse club. When you place your order make sure your lenses are available and not out of stock, because you'll need them now.

Buy your contact lenses from a supplier you're familiar with and know is reliable or has name familiarity. Always ask what rebates are available. Before you buy online, check to see if there are any testimonials at the online supplier's website.

To be sure your eyes remain healthy you shouldn't order lenses with a prescription that's expired or stock up on lenses right before the prescription is about to expire; it's much safer to be re-checked by your eye doctor. 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. The most serious safety concern with any contact lens is from overnight use.

Extended-wear rigid lenses can cause unexpected, undesirable, reshaping of the cornea. Replace your contacts as recommended by your eye doctor because they wear out as time goes by. If your eyes become red or irritated, remove the lenses immediately and consult with your doctor.

No matter which lenses your doctor prescribes, be sure to ask for written instructions and follow them carefully. If you're planning to buy contact lenses, you should buy the best quality you can get, even at a higher price; you don't want to skimp on quality when it comes to your eyes. It's becoming easier and easier all the time to shop online and often the shipping is free.