Contacts are generally categorized by material, wearability and correction ability. The greatest majority of contact lens patients wear soft lenses. Soft lenses come in a variety of disposable forms (daily, bi-weekly and monthly) as well as long-term wear lenses. Some soft lenses are considered “daily wear”, which means they must be removed before sleeping; while others are “extended wear” and may remain in the eye for several days at a time. Hard and gas permeable lenses are long-term wear lenses only, and can be either “daily wear” or “extended wear”.
Vision correction classifications for contact lenses are spherical, toric and bi-focal. Spherical contacts can correct nearsightedness and farsightedness. Toric lenses may be used to correct astigmatism. Patients with presbyopia may be able to wear bi-focal contacts to give them correction for both their distance and near vision. There are also specialty lenses that correct Astigmatism and Presbyopia, called Torics.