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Reusable vs Disposable Tonometer Prisms: How to Prevent Epidemic Keratoconjunctivitis

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Since the introduction of Dr. Goldmann's applanation tonometer (GAT) in 1950 there has been concern about cross contamination of patients due to improper tonometer prism disinfection. A recent study by Micro Scientific Industries estimated that Goldmann tonometry is performed on 122 million patients annually in North America. In 2008, The Centers for Disease Control issued a guidance document Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008 and dedicated a section on Goldmann tonometer sterilization.

The guidance document stated “One study revealed that no uniform technique was in use for disinfection of applanation tonometers, with disinfectant contact times varying from <15 sec to 20 minutes”. It went on to further explain the potential for transmission of viruses and their recommendation that the tonometer tips be wiped clean and disinfected for 5-10 minutes with either 3% hydrogen peroxide, 5000 ppm chlorine, 70% ethyl alcohol, or 70% isopropyl alcohol. Of course after disinfection they suggest the prism be thoroughly rinsed in tap water and air dried before use. In many cases a short and simple decontamination procedure is desirable for patient flow in a clinical setting which consists of using a 70% isopropyl alcohol wipe on the tonometer prism.

In the guideline document two clinical reports are referenced indicating that disinfection of tonometer tips between uses with a 70% isopropyl alcohol wipe contributed to outbreaks of epidemic keratoconjunctivitis caused 18 adenovirus type 8. The American Academy of Ophthalmology came under attack for its lax sterilization practices from a group named American Safe Sight Foundation which formed as non-profit in August 2014. The mission of ASSA is to promote public awareness and strive for eradication of preventable infectious and inflammatory eye diseases through research and education. A petition was started by ASSA with 126 supporters as of today.

In the press release by ASSA they explain about an epidemic keratoconjunctivitis cluster in a west coast community where several dozen EKC outbreaks happen at one local ophthalmologist’s office. In the press release it contains an explanation of epidemic keratoconjunctivitis preventions which can simply be implemented:

  • Use disposable tonometer prisms or non-contact tonometry devices
  • Use single use eye drops
  • Use gloves
  • Use medical-grade disinfectants to wipe all semicritical surfaces
  • Recognize that alcohol wipes are not an acceptable antiviral cleaner
  • Make EKC a legally reportable disease in the United States.

Each year new disposable (single use) products are introduced into the market to help with sterility in the operating room and concerns of cross contamination of patients by their health providers. Both Keeler and Volk have launched a series of products to answers these concerns. But in order to tackle the issue at hand one must decide if the current practices are valid or a disposable tonometer prism is best answer. A laboratory study in 2006 answered the question about infectious risk with different disinfection regimens on tonometer tips. The study indicated “We conclude that disposable prism tonometry provides a safe alternative to Goldmann tonometry”

But what about cost-benefit for changing from a reusable to a disposable prism in a private practice or large clinical setting? In May 2011, The Royal College of Ophthalmologist released a clinical paper looking at the cost analysis of Goldmann and alternative disposables devices; and the advantages /disadvantages of alternative disposable devices. When this report was release Haag-Streit was the main source of disposable prisms and since then Keeler has launched their Tonomate™ product.

The decision every practice, clinic, and hospital must decide is the current tonometer prism disinfection protocols eliminating the risk of cross-infection/alkali burns and is the savings of using a disposable the direction we must take to safe guard patients.

About the Author Eugene VanArsdale

Eugene is the Director of Marketing Communications at Keeler Instruments. He has been with Keeler since 1982 and is co-holder of two patents for the company. Eugene has a true passion for the eye care industry and has dedicated himself to understanding the ins and outs of the optometric and ophthalmic equipment market.

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