Soft contact lenses are made of a material that absorbs a certain amount of water that makes them soft and flexible. This makes the lens easy to adapt to and comfortable on the eye. Soft lenses come in a variety of materials and moisture content. The different properties of each lens are what make each soft contact lens unique in how it may fit or feel on the eye.
Disposable contact lenses are soft lenses made of varying materials having partial water content. These are designed to be replaced on a regular basis. Lens replacement schedules range from one day to two weeks to monthly. The type of lens best for you will be based on the rate your eyes produce deposits, and how the lenses are worn as well as your needs.
A hydrogel soft contact lens is a contact lens made from a plastic material that absorbs water. Once the water is absorbed, the lens becomes soft and pliable. The amount of water absorbed is dependent on the material from which the lens is manufactured.
A silicone/hydrogel soft contact lens is a soft lens made from a material that incorporates silicone into the structure of the material. This creates a polymer that allows more oxygen to pass through the lens. This is important from the eye's point of view! The more air diffusing through the lens creates a healthier environment for the surface of the eye. This is especially important if a contact lens is to be slept in overnight.
A soft contact lens that corrects astigmatism has a special design that allows the lens to orient in a stable position on the eye. This stability is important to allow an accurate correction of the astigmatism. This usually works well for small to moderate amounts of astigmatism. For higher levels of astigmatism, a rigid lens corrects more accurately.
Gas permeable or rigid contact lenses are made from a stiff plastic to correct the vision. This “rigidness” allows the contact lens to correct astigmatism more accurately. This ability to correct astigmatism is the greatest advantage of the rigid lens, in that it will usually provide very crisp and detailed vision. The adaption to wearing this lens may take longer due to the initial awareness it creates.
Hybrid contact lenses are made from a combination of rigid and soft materials combined together. The center of the lens is rigid and the peripheral skirt is made of a soft material. This creates a design that has the ability to correct the vision accurately like the rigid lens and has the comfort of a soft lens.
A bifocal contact lens has both the distance correction and near correction combined together. This allows the above “age 40” lens wearer to wear contact lenses for distance and not need reading glasses. These may be available in both soft and rigid contact lens designs.
Scleral contact lenses are large diameter rigid contact lenses designed to fit over the cornea and to rest on the white of the eye (i.e. the sclera). This is used to enhance the fit or comfort of a contact lens. This is usually used in special conditions such as keratoconus or corneal transplants.