Reprocessing and reusing single-use cataract knives can save facilities a lot of money, but does the practice put patients at risk for Creutzfeldt-Jakob disease (CJD)? The evidence to date suggests the risk is very low or non-existent. But because of the long incubation periods for the disease, it's impossible to give a definitive answer.

Prions, the mutant proteins thought to transmit CJD, can be present in corneal tissue. In the '70s, a corneal transplant patient who received an infected button subsequently died from the disease. Since then, two more corneal transplant patients have become infected, and the donor tissue is suspected as the cause.

Resisting autoclaving
If a cataract knife were used on an infected patient, the thinking goes, it's possible that the knife could be contaminated with prions. If so, and if the knife were autoclaved and reused, it's possible that some prions could survive the sterilization process. Studies show that 5 percent to 10 percent of prions resist normal autoclaving.

It's possible to kill virtually all prions by autoclaving for at least 30 minutes at a temperature of 132'C in a gravity displacement sterilizer, or 18 minutes at 134'C in a prevacuum sterilizer, according to the World Health Organization (WHO). But virtually no facilities reusing single-use knives are using such a process, says Nick Hogan, MD, PhD, an associate professor of ophthalmology and pathology, neurology and neurosurgery at the University of Texas-Southwestern Medical Center. And single-use knives might not stand up to this more intensive process anyway. Even so-called responsible knives haven't been validated for this more intensive process. So goes the theoretical case for the transfer of prions from one patient to another via cataract surgery.

Eye surgery rarely suspected
Even if transmission and infection in this way is possible, the evidence so far suggests it's highly improbable.

Classic CJD disease is extremely rare in humans. It occurs in one person in one million, says WHO. Although it's not known how many patients actually get cataract surgery, the incidence of cataract is about 40 percent in patients over 75. So the chances of operating on a person with classic CJD are less than one in 2 million.

The incidence of transmission by any kind of surgery is exceedingly low. In 80 percent to 90 percent of all cases, the cause is unknown. In 10 percent of cases, the transmission is familial. Surgery is suspected or proven as a cause in fewer than 5 percent of all documented cases.

Since 2000, 267 iatrogenic cases have been reported worldwide, according to a study published in the April issue of British Journal of Ophthalmology. Only three cases (1 percent) are thought to possibly be associated with eye surgery (one confirmed, one probable and one possible case). All are related to corneal transplants, where contaminated donor tissue presumably serves as a depot for the body's infection with prions. No one knows whether prions transmitted via an infected cataract knife would result in a systemic infection. Despite the absence of evidence to link cataract surgery or ophthalmic instruments to prion disease, experts still advise caution.

"Incubation takes up to 30 years, so we are still watching many of these (267) cases," says Dr. Hogan. "Fifty-eight of them had intraocular surgery in the past 20 years, 10 of whom were in the symptomatic phase. And the majority of the cases were cataracts."

Also, regardless of whether transmission actually takes place at your facility, "if you are using a knife that is not validated and you do have a case of CJD, your facility is going to be liable and will have to accept full responsibility," says Nancy Chobin, RN, CSPDM, central supply/supply processing department educator for the Saint Barnabas Health Care System in West Orange, N.J.

Her facility works to reduce the risk for all surgery by requiring patients to answer a pre-op survey that includes questions about

• whether the patient has experienced rapidly progressive dementia;
• whether the patient has received human growth hormone, gonadotrophin, dura mater graft or corneal transplant before 1992;
• whether the patient has spent five years in Europe since 1980; and
• whether the patient spent more than three months in the United Kingdom from 1980 to 1996.

If a patient answers yes to any of the questions, any reusable instruments are specially reprocessed to destroy any possible prions.

How sure do you want to be?
In the end, individual facilities must make their best judgement about the risk-benefit ratio of reusing single-use cataract knives.

Says Dr. Hogan, "Disposing of knives is the best way to ensure that you are not spreading the disease. When you reuse them, you put patients at an increased risk. That risk may be very low, but it's the difference of being absolutely sure and being reasonably sure."

Staff training and credits, delivered to your door
Educate your staff on key patient safety topics like "Surgical Counts," "Disaster Management" and "Positioning the Patient for Surgery" 24 hours a day, seven days a week using live and archived webcasts from PEN Online. Members take an "On-Line Program Evaluation" following the program. Once that is submitted, PEN Online sends out a Certificate of Completion. Individual memberships cost $89 per year; groups of 10 or more can get special group rates. For more information, call (800) 873-0552, visit www.penonline.org or Circle 167 on your Reader Service Card.

Convert your ESU into a smoke evacuator
PenAdapt from Buffalo Filter can adapt your electrosurgical pencil into a smoke evacuator, says the maker, Buffalo Filter. The device is made of soft, latex-free silicone and is compatible with nearly all brands of electrosurgical pencils, the company says. Pen-Adapt can be used with most smoke evacuation systems, and may also be used with filtered wall suction. The company declined to give pricing. For more information call (800) 343-2324 visit www.buffalofilter.com or Circle 168 on your Reader Service Card.