Q: Last month, you discussed the increasing reports of Acanthamoeba keratitis (AK) in our contact lens-wearing patients. What methods or care regimens can we suggest to help patients lower their risk of infection?
A: Patients should understand that there are preventable risk factors, such as [poor] hygiene, [loose compliance with a] wear regimen and certain environmental exposures, that will predispose them to infection, says Elmer Tu, M.D., director of the Cornea and External Disease Service at the University of Illinois Eye and Ear Infirmary.
Maintaining excellent hygiene and keeping lenses as clean as possible are essential practices, says Charlotte Joslin, O.D., of the
Dr. Joslin also recommends that patients avoid exposing their contact lenses to water. The probability of contracting AK increases for patients who shower while wearing their lenses.1,2 Patients need to limit their exposure to sources that could potentially increase their risk of Acanthamoeba, such as swimming or using a hot tub, while wearing contact lenses, she adds. Additionally, allowing soft contact lenses to come into contact with tap water may be problematic.
Also, consider the lenses and care products that your patients use. Hydrogen peroxide solutions have a higher likelihood of killing Acanthamoeba than any of the multipurpose solutions. Dr. Tu says.
But, depending on exposure time and concentration, even they are not completely effective against the highly resistant Acanthamoeba cyst form, Dr. Joslin adds.
Educate your patients thoroughly about how to properly clean, care for and store their lenses, regardless of wear modality. Instructions to patients should always include digital rubbing of lenses during cleaning, maintaining a clean case that is regularly replaced, and replacing lenses according to the prescribed schedule, says Dr. Joslin.
Some additional measures to helps safeguard your patients:
Make sure the patients lenses and solutions are compatible.
Create individualized case replacement schedules.2
Provide a compliance checklist and a signed compliance agreement between you and the patient.3
Make sure patients (especially those in extended-wear lenses) understand the importance of regular lens replacement. The use of daily disposable lenses may lessen patients risk of Acanthamoeba infection, due to the one-day modality.
Daily disposable lenses provide the ultimate convenience and the cleanest lens for patients, says Dr. Joslin.
Educate patients about the clinical signs and symptoms of infection. Instruct them to contact you immediately if they notice these. Early symptoms are similar toand sometimes even milder thanbacterial keratitis, Dr. Tu says. Persistent pain or decreased vision plus any unresponsiveness to traditional anti-bacterial medications should make one suspicious for atypical pathogens.
Dr. Joslin agrees. Any time patients have persistent irritation or redness, changes in vision or increasing sensitivity to sunlight, they need to be examined, she says.
Remind patients regularly that contact lenses are a prescription medical device. They carry the possible risk of vision loss and even blindness if not worn responsibly. Says Dr. Tu: No lens is completely safe, and the practitioner needs to assess each patient"s willingness and ability to comply with wear regimens to determine the best mode of vision correction for each individual.
1. Joslin, CE, Tu EY, Shoff ME, et al. The association of contact lens solution use and Acanthamoeba keratitis. Am J Ophthalmol 2007 Aug;144(2):169-80.
2. AK outbreak: Lens solution is but one factor. Rev Optom 2007 July;144(7):8.
3. Bennett E. What have we learned from the Fusarium outbreak? Rev Optom 2007 Apr;144(4):34-41.
