Contact Lens Facts
Contact lenses are miraculous pieces of plastic that allow you to see without glasses. In most cases, contact lenses are used as a substitute for glasses, allowing you to dispense with them. Contact lenses may also be used to treat certain eye diseases or may be used for cosmetic purposes to change the apparent color of your eyes.
Successful contact-lens wear requires a "partnership" between the fitter, that is, an ophthalmologist, an optometrist, or possibly an optician, and you, the wearer.
- The fitter must first decide if your eyes are healthy enough to wear contact lenses. If so, the fitter then fits the correct lenses for your eyes and your needs and teaches you how to use and care for them.
- The fitter should be available if problems develop; if not available, the fitter must then have system in place to address those situations.
- You must follow the instructions, care for, and wear the lenses correctly and return as required for routine and emergency care.
A fitter can be an ophthalmologist, an optometrist, or possibly an optician.
- Ophthalmologists are physicians who have graduated from college and a school of medicine (MD) or osteopathy (DO), after which four to six years of additional training (residency and optional fellowship) are required and spent studying about eye examinations (including fitting of contact lenses and glasses), diagnosis and treatment of eye diseases, and performing eye surgery. Ophthalmologists perform both intraocular rather than conventional surgery and laser surgery.
- Optometrists have graduated from college and a school of optometry (OD), where they are trained in eye examinations, fitting of contact lenses and glasses, and depending on state licensure, treatment of certain eye diseases. Optometrists do not perform conventional eye surgery or laser surgery. Select states permit optometrists to perform certain laser procedures only.
- Opticians fit glasses based on the prescription of an ophthalmologist or an optometrist. In some states, opticians may fit contact lenses. Opticians do not perform eye examinations, do not diagnose or treat eye diseases, and do not perform surgery.
Soft lenses and rigid gas permeable (RGP) lenses are the main types of contact lenses available. Each has specific indications as well as a specific wear and care regimen. The older hard (PMMA) lenses are rarely used today and have risks similar to RGP lenses. There are larger scleral lenses available for special eye conditions.
How to read the numbers on a contact lens case. 8.6 refers to the base curve (BC); BC is determined by measuring the curvature of the cornea.
-1.50 refers to the prescription. Photo courtesy Michelle Rhee, MD.
Contact lenses are mainly used to avoid wearing glasses in conditions such as nearsightedness, farsightedness, and astigmatism or to avoid the use of bifocal glasses once presbyopic (having trouble with near vision activities such as reading). Contact lens options for presbyopia include bifocal contact lenses, monofocal contact lenses and use of reading glasses, or monovision. Monovision, also known as blended vision, uses a technique of correcting one eye for distance vision and the other eye for near vision. Some people adjust to and enjoy this method of obtaining freedom from glasses.
Contact lenses may also be used to treat conditions other than those described above. Keratoconus is a condition in which the surface of the eye has a very irregular shape (astigmatism). When glasses no longer provide adequate vision, contact lenses are used.
Contact lenses may also be used after refractive or cataract surgery if under- or over-corrections occur. After eye surgery, and in some cases of eye diseases of the cornea, bandage soft contact lenses may be used to allow the cornea to heal or may be used to alleviate pain. They may be used in young infants or children after cataract surgery, with children who have very strong prescriptions, or when there is a big difference in the prescription between the two eyes.
- Some lenses are meant for daily wear. With daily wear soft lenses, the lenses are worn for a day, then discarded. This allows one to dispense with solutions, cleaning, and disinfection of the lenses. It allows intermittent wear such as weekend or occasional wear as desired. Most soft lenses and some RGP lenses are worn for a day and then removed, cleaned, and disinfected each night. Soft lenses are usually replaced on a regular basis, which varies from one day to one week to one month to three months to one year. RGP lenses may last for years with regular care.
- Extended wear lenses, usually soft, are worn overnight for one week and then replaced every one to two weeks. Trying to extend the wear of lenses beyond the recommended replacement schedule is a false economy and an invitation to potential disaster.
- Overnight wear decreases the amount of oxygen available to the eye and increases the (rare) chance of infection by fourfold. Because of this, some practitioners do not recommend extended wear of contact lenses. Newer lenses may be safer.
Cosmetic Contact Lenses
- Contact lenses may be used to change the color of the eyes. This may be for professional reasons such as for actors and models wanting to have a different eye color. This is of great concern when lenses are sold in stores such as gas stations and party stores during the Halloween season without a professional examination to determine the health of the eyes and the safety of wearing lenses. Every year, a number of cases of blindness are seen by ophthalmologists around the United States due to infections or damage to the eyes.