Contact Lens Types
Contact lenses can be classified in many different ways, including what they are made of, how long they can be worn, and specialty vision correction, among others. The following is an overview of some contact lens options.
Soft Contact Lenses
Soft lenses are made of a soft flexible hydrogel that allows oxygen to permeate through the lens to the eye. The first soft lens was approved by the Food and Drug Administration in 1971 for use in the United States. Most lenses prescribed today are a type of soft lens.
Soft lenses are hydrophilic, meaning they are largely made of water. It is this water content that allows them to remain soft. For most people, wearing soft lenses is immediately comfortable and does not require an adjustment time. If you find the lenses uncomfortable after you begin wearing them, you should discuss this with your eye care provider. Since so many options are available today, you may find another option to be more comfortable.
Spherical soft lenses are used to correct myopia and hyperopia. In addition, soft bifocal lenses are available to correct presbyopia.
Because soft lenses are largely water, bacteria can develop if the lenses are not properly cleaned and disinfected according to the manufacturer’s instructions. Therefore, if you wear soft lenses, you should carefully follow your eye care professional’s advice.
Rigid Gas Permeable (RGP) Lenses
When hard contact lenses were first introduced, they blocked oxygen from reaching the surface of the eye. Because oxygen is necessary for a healthy eye, these early lenses, particularly if not cleaned properly, could lead to certain eye disorders.
While patients sometimes call the current generation of such lenses 'hard', because they are not flexible like 'soft' lenses, these lenses are actually rigid lenses. They are also very different from their predecessors.
Today’s RGPs are rigid contact lenses that provide crisp vision correction for myopia, and are also now available in a bi-focal format. Unlike early generations of 'hard' lenses, rigid lenses are made of special polymers that are permeable, meaning oxygen can permeate to the surface of the eye.
Because rigid lenses are made of plastic, they do not allow bacteria to multiply and are easy to clean and disinfect. If properly maintained, RGPs can have a long life and won’t require replacement as frequently as soft lenses.
Unlike soft lenses, RGP lenses may take a certain amount of time for you to adjust to wearing them. They are not as immediately comfortable as soft lenses. However, for certain patients, the clarity of vision they provide outweigh this adjustment period. If you are unable to tolerate the rigid lenses, you can discuss other options with your eye care provider.
Disposable Contact Lenses
As the name suggests, disposable lenses are lenses that you wear for a certain period of time, according to the manufacturer’s recommendations, and then throw away. Disposable lenses can be used to correct myopia and hyperopia.
Some types of disposable lenses are listed below:
- Single or daily use lenses are worn once and simply thrown away. Because you are always using a new pair, no cleaning or disinfecting is required.
- Daily wear lenses are worn during the day, and removed and cleaned at night. Usually, you are able to use the same lenses for a 2 week period.
- Continuous wear lenses are designed to be worn 24 hours a day for a full week and then replaced.
Toric Contact Lenses
Toric lenses are a recent development in contact lenses that correct astigmatism, as well as myopia or hyperopia. Prior to this development, people with astigmatism often could not wear soft lenses. These lenses, which are available in both soft and rigid material, provide a new option for astigmats to be less dependent on eyeglasses.
Multifocal toric lenses which also correct presbyopia are available. Although toric RGPs are more common, because they tend to remain more stable on the cornea and provide sharper vision correction for many patients, soft toric lenses are also available.
Finding the Right Contact Lens
This brief overview of types of lenses demonstrates the variety of lens options available to you today. It may require a certain amount of trial and effort to find the optimum solution for your unique combination of vision correction, comfort, and convenience.