Contact Lenses are simple to wear and care for, and are almost undetectable. They are thin discs of plastic, curved on the inside to fit properly onto the surface of the eye, and shaped on the outside to correct and improve defective vision. First, your contact lenses must correct your vision problem. Second, each lens must properly fit your cornea, so contact lenses come in thousands of parameters, meaning the combination of size, shape and power. Your doctor of optometry will evaluate your eyes to determine which lens is right for you, and will take into account your special needs such as dry eyes, a desire for color change or the need for overnight wear.

Types of contact lenses:

You can choose contact lenses either hard, soft, gas permeable, continuous wear, disposable or bifocal contact lenses. These are available in many types and designs to meet your individual needs.

1. Soft lenses: Soft lenses are made from water-absorbing plastics, which make them pliable and membrane-like for maximum comfort. They are ideal for sports as they cannot be easily dislodged from the eye. Many soft contact lenses also provide UV protection. They are usually disposable and can be thrown away after a short period of use, generally every two to four weeks or daily, depending on the type of lens prescribed. Being able to have a fresh pair of lenses means less chance of infection, less cleaning, and more comfort, especially for people whose eyes naturally produce more protein that clouds lenses.

While most people choose soft contact lenses because of their benefits, there are also some disadvantages. Soft lenses easily absorb pollutants like lotion or soap from your hands, which can irritate your eyes. They are also more fragile than hard lenses and can rip or tear easily.

The most recent type of soft contact lenses to hit the market, include Daily Disposables and New Silicone Extended Wear Disposables contact lenses.

2. Hard lenses: Hard lenses didn't allow for oxygen to pass through the lens to the cornea. As they needed to be very small to leave the cornea uncovered as much as possible, they could easily fall out especially when blinking. Although these are still available for certain specialist needs they have largely been replaced by rigid gas permeable lenses.

3. Rigid gas permeable (RGP) hard contact lenses:

Rigid gas permeable lenses, or hard contact lenses, are semi-rigid lenses made usually from acrylate and fluorosilicon, a plastic which allow oxygen through to the eye. They are clinically the best as they allow maximum oxygen to reach the cornea being smaller in size. They are easy to care for, durable and give good clarity of vision. Compared to soft contact lenses, hard contacts maintain their shape better and offer clearer vision for some types of corrections. They are also extremely durable and easy to take care of. However, if you are considering this type of hard contact lens, you should know that:

• There is a 10-15 times greater risk of developing corneal ulcers, a serious infection, which may damage your vision if not treated.
• Sleeping in extended wear contacts may decrease flow of oxygen to the cornea, which can damage you vision.
• Undesirable reshaping of the cornea may occur.
• The amount of time needed to adjust to hard contacts is often repeated after not wearing them for as little as a day.

Therefore, in order to achieve maximum comfort, you have to wear the contact lenses every day.

4. Daily disposable contact lenses: Daily disposable contact lenses are only worn once and then thrown away. The benefits of Daily Disposables include never having to clean your contact lenses, convenient replacement schedule, and reduction of dry eye and irritation related to contact solutions. If you are an allergy sufferer, these are the contacts for you.

5. Silicone extended wear disposables: Silicone extended wear disposable contact lenses are made with a new material that can be worn for up to 30 nights and days. The new silicone material also prevents deposit build up and reduces dry eye irritation.

6. Bifocal contact lenses: Bifocal contact lenses are designed to give good vision to people who have a presbyopia. These lenses work much like bifocal eyeglasses, having two powers on one lens: one to correct distant vision and another to correct near vision. Bifocal contacts come as both soft and rigid gas permeable lenses.

7. Toric contact lenses: Toric contact lenses are special lenses for people with astigmatism. They made from the same material as other contact lenses and come in soft or rigid gas permeable forms. Like bifocal lenses, toric lenses have two powers, one for the astigmatism and another for myopia or hyperopia if either of these conditions is also present.

8. Contact lenses: Colored tints can be added to certain contact lenses that make them easier to see when handling, enhance or change eye color, and improve contrast for outdoor sports, like golf and softball. Contact lenses with novelty effects are available, but should still be handled and cared for like prescription lenses.