The Draw of
Disposables
A study suggests that single-use
microkeratomes may reduce
epithelial defects and enhancements.
BY MICHAEL W. BELIN, M.D.
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PHOTO COURTESY OF: NATIONAL
GEOGRAPHIC |
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Safety has always been one of the primary reasons for using disposable medical tools. This is especially true with an invasive procedure, such as LASIK. Disposable instruments minimize the danger of transmitting diseases such as hepatitis and HIV. Moreover, proteins such as those that transmit prion disease can adhere strongly to smooth metal surfaces, and studies have shown that routine cleaning and autoclaving may not remove all of them.
Disposable microkeratomes share these safety advantages. In addition, I've found disposable microkeratomes to be more efficient and easier to use; they don't need to be cleaned and sterilized or assembled. This has improved our turnaround time. In fact, since switching to disposables we've been able to function with one less technician.
Perhaps most significantly, our practice recently conducted a study comparing the results produced by a reusable microkeratome with the results produced by a disposable unit made by the same manufacturer. We found that the disposable instruments produced fewer epithelial defects, and patients required fewer enhancements.
A New Class of Products
The first disposable microkeratomes had limitations. They were poorly constructed, with poor quality control and limited flexibility in terms of flap size, hinge size and flap thickness. Those limitations, however, no longer apply.
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Making the Switch |
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Studies such as the one by Dr. Belin suggest that use of a disposable microkeratome correlates to fewer epithelial defects and enhancements. (See main article.) Surgeons who use single-use systems report other advantages as well. A number of factors convinced Robert T. Spector, M.D., medical director of the TLC Laser Eye Center, in Fairfield, Conn., that he should convert all of his LASIK cases from a reusable microkeratome to the Moria M2 90-micron single-use system. "The main advantage of the disposable microkeratome is that no hand or tool ever touches the blade, so sterility and blade edge are maintained," he says. Dr. Spector also appreciates being able to have the blade available very quickly. "Not having to sterilize the head after every use is very important for me because I use a new blade per eye -- not per pair of eyes." Another benefit that's impressed Dr. Spector is the improved reproducibility offered by the disposable microkeratome. "The disposables have zero wear because they're only used once, so I'm getting a much truer reading of close to 90 microns. As a matter of fact, I'm within a few microns of being the same with every case, which wasn't true with a metal head," he said. Dr. Spector adds that the disposable system has also created fewer epithelial defects, with excellent gutter approximation. Mark E. Whitten, M.D., regional medical director of TLC Laser Eye Centers in Washington, D.C., says that eliminating the need for sterilization is one of a disposable system's advantages; in addition to reducing the risk of contamination, not having to sterilize an instrument means cost savings in terms of both labor and chemicals. Dr. Whitten also points out that the process of sterilization has been linked to DLK. |
I've used the Moria One Use disposable microkeratome (a completely disposable version of the Moria LSK One microkeratome) in 98% of my LASIK cases for the past 2 years. (Moria is currently developing additional One Use heads that will increase flap diameter and thickness options.) The single-use suction ring, vacuum tubing and keratome head are delivered sterile, essentially providing a new keratome for each patient. Other advantages of Moria's One Use include its clear plastic applanating plate, which provides improved visualization, and its clear suction ring, which makes verifying suction easier.
Although disposables represent an ongoing cost, we've found that this cost is more than covered by our savings (using one less technician) and our increased case volume, thanks to quicker turnaround between cases.
Several microkeratomes are labeled and marketed as disposable, despite the fact that only the head is actually replaced. I don't consider these units truly disposable because reusing the vacuum ring eliminates some of the advantages of a completely disposable unit.
Looking Closely at Results
We've been studying flap thickness correlations for several years; our ongoing study now includes more than 4,000 eyes. Recently, we used this data to compare flaps made by the 130-micron head of the Moria LSK microkeratome with flaps made by the 130-micron head of the Moria One Use disposable. (Note: When comparing microkeratomes, it's crucial to compare equal flap thicknesses. We studied the incidence of epithelial defects using the Moria One Use with the 100-micron, 130-micron and 150-micron heads. Our data showed a highly statistically significant difference: The thinner the flap, the lower the incidence of epithelial defects. In short, different flap thicknesses made using the same microkeratome design can produce a dramatic difference in the incidence of epithelial defects.)
In the direct comparison of the flaps made by the disposable and reusable microkeratome 130-micron heads, the disposable microkeratome flaps had a lower incidence of epithelial defects than the reusable microkeratome flaps. This turned out to be true for any flap thickness, at a highly statistically significant p level of .001. (It's possible that the plastic material the disposable is made of is less traumatic to the epithelium than the steel used in the reusable model.)
Our study data also showed a correlation between increased epithelial defects and more frequent post-op visits -- and a greater incidence of enhancements. Patients with epithelial defects had an enhancement rate of more than 17%; eyes without defects had an enhancement rate of 7%.
The Bottom Line
The results we've achieved with a disposable microkeratome -- fewer epithelial defects and enhancements -- certainly provide support for the idea that refractive surgeons should use disposable instruments whenever possible.
Michael W. Belin, M.D., is medical director of TLC Laser Eye Center in Albany, N.Y., and is in private practice at Cornea Consultants of Albany. He is a professor and director of cornea & refractive surgery at Albany Medical College, and an adjunct professor at the University of Ottawa in Ontario. Dr. Belin has no financial interest in any of the products mentioned.
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It Comes Down to Physician Preference |
As with any category of refractive surgery products, practices have options when it comes to microkeratomes. One of the choices to make is whether to use nondisposables or disposables. Each has advantages and disadvantages, says Kerry Assil, M.D., Medical Director and CEO of The Assil-Sinskey Eye Institute in Santa Monica, Calif. "With disposables, for example, you have assured sterility and no cleaning between cases," says Dr. Assil. The no-cleaning aspect could be attractive to a busy practice or a low-volume practice: the former because turnaround time is quicker, and the latter because fewer technicians are needed. Or, either of those practices could consider having to maintain an inventory a disadvantage. "It all comes down to physician preference," says Dr. Assil. "I prefer the Amadeus reusable microkeratome because in my experience it's the most precise in the sense that we can adjust flap diameter and hinge width and we can adjust flap thickness to fit the needs of each patient. It's friendly to the epithelium as well. There is, however, no substitute for my staff understanding the importance of proper cleaning and maintenance." |
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