There are several types of contact lenses available today:
Soft contact lenses. Most people who need corrective contact lenses are able to wear soft contacts. These lenses are made of a polymer-plastic material and water. The water allows oxygen to pass through the lens easily, which is healthier for the eye and makes the lenses more comfortable to wear — even for first-time users.
Two of the most popular types of soft lenses are daily disposable lenses and extended wear lenses. Daily disposables are worn for one day and then discarded. These are extremely easy to care for and don’t require additional soaking or rinsing.
Rigid gas permeable lenses (RGP lenses) are more durable than soft lenses, and can provide more clarity of vision. The newer versions of RGP lenses are made with silicone polymers, which aid in oxygen circulation through the lens to the cornea. Your eyes may take more time to adjust to RGP lenses because RGP lenses are not as flexible as soft lenses. Therefore, daily use is recommended.
Also unlike older versions of hard lenses, some RGP lenses are designed for extended wear, which means they can be worn overnight. Since sleeping in your lenses can reduce the amount of oxygen entering your eye (since your eyes are closed), it’s important to get regular check-ups from your eye doctor and follow all wearing and cleaning instructions for your extended wear RGP lenses.
High DK Lenses. The popularity of hyper-oxygen-transmissible lenses — also known as High DK or Extended Wear lenses — took off in the past few years. Now, technology has allowed lens manufacturers to create high DK lenses for daily and extended wear use that actually may reduce the risk of microbial keratitis, a bacterial infection on the cornea.
More oxygen passes through High DK lenses, which keeps both the lens and the cornea fresh and protected from bacterial build-up. In some cases, the extended wear lenses are preferred over corrective eye surgery, such as LASIK, since the risks of surgical complications are eliminated.
High Water Lenses. No, High Water Lenses are not contacts designed for use while you swim! Rather, these soft lenses are made with a high percentage of water. This water makes the passing of oxygen through the lens to the eye more effective, allowing the eye to “breathe.”
The soft contact lenses that were first manufactured were called “Low Water Content” soft lenses. They contain around 38% water. Modern soft lenses are now between 50% and 60% water. Some lenses are as much as 70% water, which means that only 30% of the lens is actually plastic!
Lenses that contain more than 65% water content are usually labeled “High Water Content.” “Mid Water” lenses are those that have between 50% and 65% water.
Silicone hydrogel lenses are super-permeable and a significant step above traditional soft lenses, which are made of hydrogel polymers. (The polymers are plastics containing water. Since plastic cannot carry oxygen through the lens, the water within it serves this purpose.)
Silicone hydrogel allows more oxygen to pass through the lenses to the cornea, making them safer and more comfortable for longer periods of wear. Those who want to sleep in their lenses and/or for whom corrective surgery is not an option can be ideal candidates for silicone hydrogel lenses, depending on the vision correction they need.
Cosmetic lenses or enhancers can correct your vision or just change your eye color or appearance. Some cosmetic lenses are cheaply produced and have an unnatural look to them — so be careful when you order them. Also, never order cosmetic lenses without an eye exam and professional fitting first. If they don’t fit you correctly, your eyes can dry out, leaving you vulnerable to a serious eye infection.