March 12, 2002 -- Approximately 36 million people in the United States wear contact lenses. Of these, more than 25,000 develop contact lens-related corneal infections each year. Such infections can lead to scarring and potential blindness.
Contact lenses, disinfection solutions and storage cases can easily become contaminated with bacteria, fungi, and free-living protozoa called Acanthamoeba.
A study recently published in the British Journal of Ophthalmology raises the concern that some commercially available contact lens storage solutions are not capable of killing Acanthamoeba.
Such single-celled pathogens, commonly found in tap water, swimming pools, lakes, and hot tubs, can attach to new or worn soft or hard contact lenses and lead to painful, progressive corneal infections.
Risks for Acanthamoeba Infection
Contact lens use is the single greatest risk factor for developing ocular Acanthamoeba infection.
Acanthamoeba-contaminated tap water or non-sterile solutions used to rinse the contact lenses or storage case can also harbor bacteria or fungi, which the Acanthamoeba ingest as an energy source to thrive and multiply. Acanthamoeba readily adhere to contact lenses, which carry the amoeba to the cornea.
Always Remember to 'RSVP'
Contact lenses are medical devices, which, by law, require prescription by an eye care professional. Patient education and periodic examination by either an eye doctor or optometrist are essential to maintaining the eye health of contact-lens wearers.
The warning signs of contact lens infection are represented by the acronym "RSVP", where R=redness, SV=sudden visual loss, and P=pain. If any of these signs or symptoms occurs, immediately remove your contact lenses. Do not patch the eye, as this may actually accelerate the infection.
This is a true eye emergency; time is of the essence and one should seek immediate evaluation by an eye care professional.
Contact Lens Disinfection Comes in 3 Flavors
There are 3 disinfection systems available for contact lenses — heat, chemical disinfection and oxidation using hydrogen peroxide.
Generally, heat disinfection is most effective in killing Acanthamoeba, followed by hydrogen peroxide systems where the hydrogen peroxide deactivator is added only after the amoeba are killed. Chemical disinfectants vary in their ability to kill Acanthamoeba, as well as fungi.
The Top 12 'Dos and Don'ts' for Contact-lens Wearers
What can you do to limit your risk of developing such an eye infection?
1. Wash your hands before you touch your contact lenses, each and every time!
2. Remove gas permeable and daily-wear soft contact lenses nightly and extended-wear lenses at regular intervals.
3. Quit smoking, as this has been shown to increase the risk of contact lens infection.
4. Regularly schedule follow-up examinations with an experienced eye care professional, to have your contact lenses refit and replaced on schedule.
5. Clean and disinfect contact lenses after each removal using an FDA-approved lens care system and according to the manufacturer's recommendation.
6. Do not use distilled water and salt tablets to make saline. Non-preserved solutions will not protect against infection and must not be reused.
7. Use clean cases and sterile solutions. Discard and replace cases periodically. Clean the lenses and lens case with a cleaning solution and boil or microwave cases routinely.
8. Refrain from moistening contact lenses prior to insertion with any non-sterile solution, especially saliva or tap water.
9. Do not swim, bathe or enter hot tubs wearing contact lenses.
10. Remove lenses immediately if any eye trauma occurs.
11. Minimize the use of topical solutions during contact lens wear and avoid contamination of eye-drop bottles.
12. Tears have been shown to harbor hepatitis C and B, and the AIDS virus- HIV. Therefore, never swap or trade contact lenses with others.
Dr. Pepose is Professor of Clinical Ophthalmology at Washington University School of Medicine, St. Louis, Missouri and Associate Editor of The American Journal of Ophthalmology and the textbook Ocular Infection and Immunity (Mosby).