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Acanthamoeba Keratitis 2011 Investigation FAQs

Why was CDC investigating reports of Acanthamoeba keratitis?

CDC had been monitoring Acanthamoeba keratitis (AK) infections since the investigation of an AK outbreak in 2007 that resulted in a recall of a contact lens solution in 2007. Initially, reports of AK cases declined following the recall, but information from reporting partners now appears to show that the numbers of AK cases still remain elevated above the numbers reported in the years prior to the outbreak. An AK Investigation Team (AKIT) was formed to investigate the risk factors that might be associated with new AK cases. The AKIT included CDC; other federal, state, and local public health partners; partner ophthalmology centers and laboratories; academic institutions around the country; and professional academies of eye care providers. The AKIT started its investigation on March 21, 2011.

How was the elevated number of nationwide AK cases detected?

As part of a 2007 AK outbreak investigation, CDC established an informal surveillance system with reference laboratories and ophthalmology centers nationwide to follow trends in the occurrence of AK cases in the United States. After an initial decline in the number of cases being reported from these centers following the recall of a contact lens solution in 2007, AK case reporting leveled off but the number of cases reported from these centers has not returned to the levels noted before the 2007 outbreak.

Why have cases not decreased to pre-outbreak levels?

At this point, public health officials do not know why the numbers of reported AK cases have not returned to levels seen in the years before the 2007 outbreak. The 2011 AK investigation was conducted to determine whether there are common risk factors for AK among infected people across the country.

How was information being collected on people with AK?

Standardized interviews of people with AK, their treating ophthalmologists, and their primary eye care providers were conducted by state and local health officials and staff at CDC. Similar interviews were also conducted with contact lens wearers 12 years of age and older who have never had AK. The AK Investigation Team (AKIT) then compared the information from AK case-patients with contact lens wearers without AK to better understand why certain people get this disease and others do not.

Where were AK cases occurring?

Nationwide. The reporting reference laboratories and ophthalmology centers are in 15 states geographically distributed across the United States. Public health officials worked with these and other centers to obtain contact information for people diagnosed with AK. AK case-patients were identified in more than 30 states.

How many people get AK each year?

AK is a rare disease, and information about the number of people who get AK each year is limited because AK cases are not required to be reported to state health departments or CDC. Information about the previous AK outbreak investigation can be found on the Publications, Data, & Statistics page.

How can I reduce my risk for getting AK if I wear contact lenses?

Contact lens use is very common among people who get AK. Although public health officials do not yet know what risk factors are involved in this apparent increase, all contact lens users should follow these recommendations to help reduce their risk for AK and other eye infections:

Visit your eye care provider for regular eye examinations.

Wear and replace contact lenses according to the schedule prescribed by your eye care provider.

Remove contact lenses before any activity involving contact with water, including showering, using a hot tub, or swimming.

Wash hands with soap and water and dry before handling contact lenses.

Clean contact lenses according to instructions from your eye care provider and the manufacturer’s guidelines.

Never reuse or top off old solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored.

Never use saline solution or rewetting drops to disinfect lenses. Neither solution is an effective or approved disinfectant.

Be sure to clean, rub, and rinse your lenses each time you remove your lenses. Rubbing and rinsing your contact lenses will aid in removing harmful microbes and residues.

Store reusable lenses in the proper storage case.

Storage cases should be rubbed and rinsed with sterile contact lens solution (never use tap water), emptied, and left open to dry after each use.

Replace storage cases at least once every three months.

Contact lens users with questions regarding which solutions are best for them should consult their eye care providers. They should also consult their eye care providers if they have any of the following symptoms: eye pain or redness, blurred vision, sensitivity to light, sensation of something in the eye, or excessive tearing.