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Task force report offers contact lens solution safety warnings
Members assert that many patients affected by the recent Acanthamoeba keratitis outbreak did not practice proper contact lens hygiene.
 Terrence P. O'Brien |
The recent outbreak of Acanthamoeba keratitis and subsequent recall of Advanced Medical Optics’ Complete MoisturePlus marks the second global recall of a contact lens solution in the past year. Not surprisingly, the news has raised several questions and safety concerns regarding multipurpose contact lens solutions.
Two members of the American Society of Cataract and Refractive Surgery Infectious Disease Task Force, Ocular Surgery News Cornea/External Disease Section Members Terrence P. O’Brien, MD, and Eric D. Donnenfeld, MD, spoke with OSN about the causes behind the outbreak and its implications for the ophthalmic community and industry.
A ‘perfect storm’
The recent outbreak was caused by many factors, including patient non-compliance and a class of multipurpose solutions that do not effectively kill Acanthamoeba, according to Drs. O’Brien and Donnenfeld.
AMO, which recalled its Complete MoisturePlus contact lens solution in May, made several changes to the solution that combined to create a “perfect storm” for inviting Acanthamoeba infections, Dr. O’Brien said.
First, the company included a disinfectant that may be less effective against Acanthamoeba than those used in other multipurpose solutions. Second, to increase comfort, the company added an amino acid-like substance called taurine, which has been known to convert trophozoites, the active form of Acanthamoeba, into cysts, the inactive form, he said. Cysts are significantly harder to kill, he said.
Complicating matters, Dr. O’Brien said, are the popular silicone hydrogel contact lenses, which uptake disinfectants and release them on the eye.
“When the patient puts the lens on after storing it overnight, there’s a huge release of the disinfecting agent onto the surface of the eye that causes some roughening up of the surface,” he said. “So this is the perfect set up [for infection], because … the disinfectant is not as good as some of the others, and then you add this taurine that converts the trophozoites into the more difficult to kill cysts. It’s a self-fulfilling prophecy.”
 Eric D. Donnenfeld |
Furthermore, Dr. Donnenfeld said, Complete MoisturePlus has hydroxypropyl methylcellulose, which, like the surfactant that came under suspicion in Bausch & Lomb’s ReNu with MoistureLoc solution in 2005, can create a residue that sustains opportunistic infections. (B&L removed ReNu with MoistureLoc from the market in May 2006 after cases of Fusarium keratitis were reported.) Improper hygiene practices can lead to the creation of a biofilm and subsequent infection, Dr. O’Brien said.
“A lot of people don’t throw out the old solution, clean the case and start anew. They sometimes just splash out the old and top it off, or they’ll keep some of the same solution in the receptacle. So now you’re getting a buildup of this material, and as the aqueous component dehydrates or evaporates, you’re left with this biofilm that will support the organisms that are in the environment anyway. They’ll get in there, stay in there and bind to the lens,” he said.
Many of the patients diagnosed with Acanthamoeba keratitis did not practice proper contact lens hygiene, Dr. Donnenfeld said.
“The Acanthamoeba was not induced into the contact lens solutions because of contamination. It was induced because the patients either mishandled their contact lenses or used tap water. Part of the responsibility is with the patient, and part of it lies with the physicians who have to instruct their contact lens wearers on proper hygiene,” he said.
Some of the responsibility also falls to the industry, which in recent years has moved toward one-step, “no rub” solutions for patient convenience and marketability, Drs. O’Brien and Donnenfeld said.
“To put this in perspective, we always have to balance convenience with safety. Clearly a single step multipurpose disinfection system … makes life easier and theoretically safer by having an agent that would simultaneously disinfect and lubricate all-in-one,” Dr. O’Brien said.
Earlier two- or three-step processes were excellent for disinfection but were “cumbersome” and presented compliance problems, as many patients did not understand the product instructions, he said.
“But what we’re seeing now is that there may be a trade-off, and both the fungal keratitis epidemic and the Acanthamoeba are multifactorial, and it’s not just the solution alone that’s to blame,” Dr. O’Brien said.
“The task force believes that ‘no rub’ solutions are not the best way to disinfect a contact lens,” Dr. Donnenfeld said. “Right now [manufacturers] are advertising these systems to be used with no rubbing, but the task force would suggest that even if you are using a multipurpose solution, rubbing is an important step in the cleaning process. … I think the problem with the recent outbreak of Acanthamoeba is an industry-wide problem that’s endemic to all of the different contact lens solutions.”
Preventing infections
The ophthalmic community was caught somewhat off guard by the last two lens solutions recalls and has addressed the problems in a reactionary mode. Drs. O’Brien and Donnenfeld spoke with OSN on how to become proactive about preventing infections.
“It goes back to the Food and Drug Administration,” Dr. O’Brien said. “We don’t want to create an approval process that is excessively rigid … but I do think we have to have a post-approval surveillance system that is more sophisticated and more astute and keen to pick up on trends that occur.”
Dr. Donnenfeld said the FDA must also re-evaluate the effectiveness of preservatives in preventing infection.
“Right now, according to FDA guidelines for preservatives, a preservative doesn’t even have to kill a fungus or Acanthamoeba to be approved. It only has to prevent growth. So, more stringent guidelines need to be put in place. Preservatives have to kill, not only bacteria, but also other organisms, including Acanthamoeba.
“Right now we’re centering on two different companies that have had recalls, but I think this has to be an industry-wide concept. It’s really a problem that is ubiquitous within the entire industry of contact lens solutions and artificial tears,” he said.
Dr. Donnenfeld also said the FDA must broaden its view of potential pathogens when evaluating contact lens solutions.
“In the most recent outbreak of Acanthamoeba, the FDA wasn’t even considering Acanthamoeba as a pathogen when looking at contact lens solutions. We have to start thinking about methicillin-resistant staph infections, Staphylococcus epidermidis and fungi other than Fusarium,” he said.
In addition, “there has to be a more active sterilization process, including heat disinfection, hydrogen peroxide and mechanical rubbing,” Dr. Donnenfeld said. “Strong consideration should be given to what’s done in Europe, where hydrogen peroxide is the most common form of disinfection of contact lenses. And even though it’s a little more time-consuming, it does a better job.
“No multipurpose solution by any manufacturer provides complete kill against trophs and cysts, and Acanthamoeba infections were found with all brands of multipurpose solution contact lens cleaners. Right now, peroxides are the best alternative to do well against Acanthamoeba,” he said.
Dr. O’Brien noted that going back to peroxide solutions and heat disinfection may not be necessary at this point.
“Just because the automobile has had an accident or two, we don’t need to go back to the horse and buggy,” he said. “There are some of the multipurpose solutions that are doing well and have not been disproportionally linked to infection.”
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Diagnosis and treatment
In an alert issued by ASCRS, members of the task force explained how to diagnose and treat patients with an Acanthamoeba infection. Patients with Acanthamoeba keratitis tend to present with nonspecific symptoms similar to bacterial or viral keratitis, they said.
If a patient presents with large, purulent, central ulcers extending into the middle to deep stroma, the task force recommends taking a culture. It also suggests culturing any ulcers that are clinically suspicious for mycobacterial, fungal or amoebic infections or ones that are refractory to initial broad spectrum antibiotics.
In taking the culture, surgeons should use a sterile platinum spatula to scrape the leading edge and base of the ulcer, while making sure to avoid contamination from the lids and lashes. For topical anesthesia, the task force prefers proparacaine hydrochloride because it has fewer antibacterial properties than other anesthetics.
Corneal biopsies may be required in cases of deep stromal suppuration or progressive microbial keratitis that is unresponsive to therapy, according to the alert.
The treatment process “is long, involves toxic medications, and may be unsuccessful in curing the infection if the infection involves the posterior cornea,” they wrote. “Only neomycin, which is contained in Neosporin, is commercially available in the United States. The other medications must be compounded by a specialty pharmacy before use. Medications must be used for months starting at hourly intervals and tapered as the clinical situation improves,” according to the task force report.
For more information:
- Eric D. Donnenfeld, MD, can be reached at Ryan Medical Arts Building, 2000 N. Village Ave., Rockville Centre, NY 11570; 1-516-766-2519; e-mail: eddoph@aol.com.
- Terrence P. O’Brien, MD, can be reached at Bascom Palmer Eye Institute, 7108 Fairway Drive, Palm Beach Gardens, FL 33418; 561-515-1544; fax: 561-515-1588; e-mail: tobrien@med.miami.edu.
- Advanced Medical Optics, maker of Complete MoisturePlus, can be reached at 1700 E. St. Andrew Place, Santa Ana, CA 92705; 714-247-8200; fax: 714-247-8672; Web site: www.amo-inc.com.
- Andy Moskowitz is an OSN Staff Writer who covers all aspects of ophthalmology.