Colored contact lenses come in three kinds: visibility tints, enhancement tints and opaque color tints.

Many of these colored contact lenses are available in plano form, as well as in designs for people who have astigmatism, need bifocals or want a disposable contact lens.

A visibility tint is usually a light blue or green tint added to a lens, just to help you see it better during insertion and removal, or if you drop it. Since it's a very light tint, it does not affect your eye color.

An enhancement tint is a solid but translucent (see-through) tint that is a little darker than a visibility tint. An enhancement tint does change your eye color. As the name implies, it's meant to enhance the existing color of your eyes. These types of tints are usually best for people who have light colored eyes and want to make their eye color more intense.

Color tints are deeper, opaque tints that can change your eye color completely. Usually they are made of patterns of solid colors. If you have dark eyes, you'll need this type of color contact lens to change your eye color. Color contacts come in a wide variety of colors, including hazel, green, blue, violet, amethyst and gray.

The companies that make colored contact lenses have gone all out to mimic the natural look of the colored portion of the eye, called the iris. Since this area is made up of colorful shapes and lines, some color contacts feature a series of tiny colored dots on the lens to make them look more natural on the eye.

But the center of the lens, the part that lies over your pupil, is clear so you can see.

Costume or theatrical contact lenses also fall into the category of opaque color tints. Long used in the movies (examples are The Man Who Fell to Earth and Twilight), these special-effect contact lenses are now widely available for novelty use and can temporarily transform the wearer into an alien or jaguar, among others.

Some Disadvantages of Color Contact Lenses
Although there are different sized lenses to fit most wearers, there will be some occasions (such as during blinking) where the colored portion may slide somewhat over the pupil.

Also, the size of your pupil is constantly changing to accommodate varying light conditions — so sometimes, like at night, your pupil may be larger than the clear center of the lens. In these instances, your vision may be slightly affected.

If you have a persistent problem with your contacts, it's important to see your eye doctor.

Sharing Contacts: A Bad Idea
While color contacts can be fun, doctors warn wearers not to share their colored lenses — or any contact lenses, for that matter — with friends, and not to swap colors with friends.

Contact lenses are medical devices and are fitted to the specifications of each individual's eyes. Exchanging lenses can also transmit harmful bacteria, which can lead to an eye infection or other potentially dangerous eye conditions.

Color contacts, like clear contact lenses, must be properly cleaned and disinfected with appropriate cleaning products. Ask your doctor which cleaning products are best for your particular lenses.

Do You Need a Prescription for Colored Contact Lenses?
Yes, under U.S. law you need a contact lens prescription. This is true even for "plano" lenses that don't have prescriptive power.

In November 2005, President George W. Bush signed into law Public Law 109-96 (sometimes referred to as the Plano Contact Lens Law), which classifies all contact lenses — including color contact lenses and prosthetic contact lenses that do not contain any power to correct vision problems — as medical devices under the Federal Food, Drug, and Cosmetic Act. Among other things, this classification demands that all contact lenses, worn for any purpose, require a valid contact lens prescription written by an eye doctor and cannot be sold to consumers without one.

If you see color contact lenses being sold in a flea market, it is likely that the vendors are breaking the law. Recently flea market vendors in Jacksonville, Fla., were warned to stop selling color contact lenses and were, pending investigation, subject to being charged with a misdemeanor for selling them without a state license.

Other illegal sales of cosmetic contact lenses have been discovered in gas stations, beauty salons and novelty shops.