Today, contact lenses fall into two categories: soft contact lenses that are made from water-containing plastics, and GP or “oxygen permeable” rigid contact lenses.
Contact Lenses may also be classified by wearing schedule. Daily wear contacts must be removed, cleaned and stored each night, while extended wear contact lenses are made from materials which are safe for overnight wear. Sometimes “continuous wear” is used for a type of extended wear lens that can be worn for up to 30 days.
Contact Lenses can also be described by replacement interval, how often you discard the lenses and replace them with a fresh pair.
What are your best options ?
Daily disposable lenses are discarded nightly and therefore require no care, cleaning or lens case. Other common replacement intervals are weekly, bi-weekly, monthly or quarterly; any of those lenses can be called “disposable.” Traditional, non-disposable lenses are usually replaced once a year, but these lenses are generally limited to unusual or difficult-to-manufacture prescriptions.
Various contacts designs are available for different vision problems. Spherical contact lenses correct nearsightedness or farsightedness and are indicated by a minus or plus in your prescription, respectively. Bifocal contact lenses are similar to multifocal eyeglasses in that they use different optical zones to correct presbyopia. Toric contact lenses correct astigmatism, which can accompany either nearsightedness or farsightedness.
Contact designs come in colors that can enhance or change your natural eye color. Special-effect contact lenses are also available for novelty use and are used extensively in theatrical and filmed productions. Prosthetic lenses are colored that can cosmetically mask eye disfigurement. Many contact lenses come with an embedded UV inhibitor as well.
Factors involved in prescribing the best contacts for your needs include: the size and shape of your eyes; your refractive error ; whether you have presbyopia or dry eyes; your desired wearing time and lens replacement schedule; whether you want lenses that enhance or change your eye color; your willingness to clean and care for the lenses daily.