There are many types of specialty contact lenses for astigmatism, presbyopia, myopia, hyperopia, keratoconus and other eye conditions. Each contact lens type has advantages and disadvantages. Below is a brief description of some of the specialty lens designs.
Soft lenses are made from softer more pliable materials that conform to the shape of the eye. Soft contact lenses allow oxygen to pass through to the cornea. They may be easier to adjust to and are more comfortable but may not provide the best, most stable vision. Soft lens materials include hydrogel and newer silicone-hydrogels materials. Silicone Hydrogel materials will provide more oxygen to the cornea.
These are referred to as GP (gas permeable) lenses and are made from a more durable rigid material that provides crisper clearer vision. The lenses tend to be smaller than soft lenses and cover only 70-80% of the cornea. GP contact lenses are designed to last much longer than soft lenses, but sometimes take a little longer to adapt to and may not be as comfortable as soft contact lenses.
Hybrid lenses are a combination of soft and rigid lens materials. They have a rigid GP lens center and a soft skirt that drapes over the scleral (or white part of the eye). These lenses offer vision benefits of a GP lens while providing comfort similar to a soft lens.
Scleral lenses are larger diameter GP lenses made with the same materials as rigid lenses. These lenses are used primarily for irregular cornea conditions as an alternative to traditional soft, rigid or hybrid lenses. They are designed to vault completely over the corneal condition and land on the white part of the eye, called the sclera. The sclera supports the lens allowing the lens to vault over the condition without interaction with the sensitive cornea.
There are many types of specialty contact lenses. Find an eye care practitioner to help you determine what lens type is appropriate for you.