How single-use diagnostic lenses yield multiple benefits for clinics

Take-home:

Single-use lenses for anterior segment lasers may reduce the risk of disease transmission and eliminate reductions in optical quality that occur over time with reusable lenses.

By Nancy Groves; Reviewed by Professor John Marshall, PhD

London-A line of single-use diagnostic and treatment lenses (Quantel Medical) offers clinicians the dual advantages of pristine optics with every use and a reduced risk of infection from improper cleaning and sterilization procedures.

These anterior segment lenses for diagnostic, surgical, and therapeutic procedures, which are packaged in a sterile pouch, offer a solution to many of the concerns associated with traditional single-use lenses-disease transmission and loss of therapeutic efficacy, said Professor John Marshall, PhD, Frost Professor of Ophthalmology, Moorfields Eye Hospital, London.

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“The optical quality of these lenses is as good as any classical lens with the added advantage that each time you do a procedure, effectively you have a brand new, perfect lens,” Dr. Marshall said. “Whereas with a classical lens system, it’s been cleaned, it’s been wiped, it’s been sterilized, and obviously the optical quality goes down as a function of use.

“If you take an average lens out of its container in an average clinic, you will see fingerprints, you will see scratches, you will see dust,” he said. “In theory, the lens has been cleaned or sterilized; in practice, that may or may not have happened.”

In a busy hospital, such as Moorfields, there is a horrendous problem with lenses due to heavy usage, theft, and damage, and high costs for cleaning and sterilization-largely due to staffing requirements, he added.

Growth in single-use items

Reducing the risk that disease can be transmitted through reusable medical products is a primary reason for growth in single-use items. The so-called “mad cow disease” (bovine spongiform encephalopathy-BSE) scare in the United Kingdom and Europe during the 1990s-in which evidence suggested an association between BSE and a new human prion disease called variant Creutzfeldt-Jakob disease-made everyone aware of the almost total inability to sterilize instrumentation in the presence of prions, Dr. Marshall said.

As a result, there has been increasing pressure in the United Kingdom toward single-use devices for any neurological tissue, and legislation mandating their use appears likely.

“There was resistance initially, but as single-use instrumentation improved, that resistance has pretty much gone,” he said.

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There have also been numerous reports in the ophthalmic literature of outbreaks of epidemic keratoconjunctivitis associated with human adenovirus infections resulting from attendance at eye clinics, likely attributable to lax disinfection and sterilization procedures for reusable instruments, he continued. Though such outbreaks are far from everyday occurrences, the risk may be greater than that of BSE and high enough for at least some facilities to re-evaluate their infection control protocols and consider more widespread use of disposable lenses.

Optical quality

The other main force behind the burgeoning interest in single-use lenses is the wear and tear that over time will reduce the image quality of reusable products. This is no longer a consideration with lenses used only once.

“Every time you do a treatment involving these lasers, essentially you’re using a new lens so the optics are absolutely perfect,” Dr. Marshall said. “You aren’t dealing with scratched optics or optics that have been dropped or chipped or optics that have been cleaned so many times that they’ve begun to fatigue and slightly yellow.”

Transmission loss in aging reusable lenses also is a thing of the past.

“With these lenses, you have 100% of the laser output delivered, whereas with conventional lenses you’re losing anywhere up to 20%, so you have to keep turning the energy up,” he said.

Advances in technology have enabled the development of single-use lenses such as those from Quantel, which have larger, flatter mirrors that result in a wider field of view, Dr. Marshall added.

“This is completely novel technology in that it wouldn’t have been possible until relatively recently to produce lenses of such high quality so inexpensively,” he said. “That’s a major technology pre-requirement.

“If you do an analysis of the cost effectiveness of these lenses, again it’s a winner,” Dr. Marshall said. “The number of procedures will determine exactly how much money you save, but even if you’re only doing a relatively small number, you will still achieve savings on sterilization and cleaning.”

An analysis performed by Sensor Medical Technology, which manufactures the lenses, compared the costs of using a four-mirror gonioscopy lens for 240 procedures a year with reusable and single-use lenses in two settings. In a hospital, the costs of lenses, disinfecting materials, transportation to and from cleaning, disinfection, packaging, staff time, and cost per procedure was $11,042 for eight reusable lenses and $2,304 for the single-use lenses, a savings of $8,738. In a private practice, the costs were $3,567.50 for two reusable lenses and $2,304 for single-use lenses, a savings of $1,263.50 per year with the single-use items.

Interest in single-use lenses is building outside of the United Kingdom as well, for the same reasons that hospitals such as Moorfields are switching to these products.

“A lot of people like the idea of a nice, fresh optic and use it as a sort-of premium, having a personal optic for every treatment, as it were,” Dr. Marshall said. “Other people are building on the idea of infection-free treatment.”

John Marshall, PhD

E: eye.marshall@googlemail.com

Dr. Marshall has served as a lecturer for Quantel Medical.