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Types of Contact Lenses

Hard Contact lenses
There are very few hard contact wearers today due to improvements in other types. Hard contact lenses are made of hard plastic material and come as either non-gas permeable or gas permeable. They provide clear vision and last a long time (5 to 10 years) but are harder to adjust to. They are harder to insert and take out but correct most vision problems. Non-gas permeable lenses do not allow oxygen to reach the cornea. These lenses have a limited wearing time because major damage can occur to the eye if no oxygen passes through to the cornea. Gas permeable lenses offer the same advantages but also allow longer wearing time and greater comfort since oxygen can flow easily through them.

Daily wear soft contact lenses
Daily wear soft lenses are made of polymer-plastic materials that are flexible. These lenses allow oxygen to pass through to the cornea, provide great comfort, and are easy to adjust to. They can also be worn for longer periods of time and can come in different colors. Some drawbacks include a shorter life span, an inability to correct some vision problems, and a lack of durability.

Extended wear lenses
Extended wear lenses are soft lenses that have been made to allow for longer periods of time (about 7 days) without removal and cleaning. These lenses allow more oxygen to pass through to the cornea. An example of these types of lenses is Focus® NIGHT & DAY™; lenses which allow for 30 nights of continuous wear. These lenses are made from silicone hydrogel that allows up to 6 times more oxygen to pass through than disposable lenses, do not dry up as much as ordinary soft contact lenses, and have a bio-compatible lens surface that decreases protein and bacteria buildup. As with all extended wear lenses there is always a chance of affecting eye health even if there are no apparent problems.

Rigid gas-permeable (RGP) lenses
Rigid gas-permeable lenses are similar to hard contact lenses but are made of better material that allows more oxygen to pass through than even soft contacts. They are made of hard plastic that gives crisp vision and corrects most vision problems. They are durable and have a longer life span than soft contact lenses. Like hard lenses they do require some time to get used to and are not recommended for highly physical activities.

Disposable lenses
Disposable lenses are designed to be worn for a limited time and then discarded. Disposables have a replacement schedule which can range from 1 day to 3 months depending on how well they are taken care of and the environment in which they are worn. Usually the typical replacement schedule is 2 weeks. Daily wear disposables lenses should be taken out daily and cleaned until the replacement schedule. Extended wear disposables lenses can be worn overnight but should still be cleaned and disinfected to prevent eye problems. Disposable lenses are more comfortable and easy to maintain because they are used till the replacement time and just thrown away.




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