Types of Contact Lenses
All contact lenses are discs that sit over the eye. They do not sit directly on the eye, rather on the tear film that covers the cornea. The optical power of the lens is able to correct vision deficiencies.
Contact lenses can be classified in one of three ways:
Decorative: To change the appearance of the eye.
Therapeutic: Lenses for the treatment of non-refractive disorders of the eye.
Corrective: Lenses to correct refractive disorders.
Soft lenses: Lenses that are manufactured from plastic materials that are able to absorb water, also called "hydrogels." They range from low oxygen permeability to high oxygen permeability (silicone hydrogels).
Rigid Gas Permeable Lenses (GP Lenses): Contact Lenses that are manufactured from plastic materials that have a high oxygen permeability and do not contain water.
Conventional: No prescribed replacement schedule. The contact lens is replaced when it wears out, becomes damaged, or the patient's power requirements change.
Planned: There is a specific time period after which the contact lens will be replaced.
Disposable: A contact lens that is disposed of upon removal from the eye and replaced.