Creating consistent quality flaps is the most important factor in achieving good visual results after LASIK. In an attempt to allow you to decrease operating costs while maintaining quality, several companies provide generic microkeratome blades, often referred to as “third-party” blades. Refractive surgeons agree that careful evaluation of all microkeratome blades is vital for outcomes. Complications from a defective blade include interface debris, buttonholes and variability of flap thickness. This article features tips on evaluating these blades.

Initial Evaluations
Atlanta surgeon R. Doyle Stulting inspects third-party blades with scanning electron microscopy to look at the surface, the consistency of the edge and any debris that might be present. “We want to see a clean blade with a uniform edge and no nicks, bends and defects,” he says. “We want the surface of the metal to look smooth and uniform.” He then inspects the individual blades again under the operating microscope prior to use. “We try to judge the quality of the surface using light reflected from it to highlight any irregularities for foreign material on the blades, and we look of obvious defects,” he says.

Brandon, Manitoba surgeon Guillermo Rocha also tests the blades under a scanning electron microscope. “Any defect in the cutting edge will produce a tear in the tissue and will result in a less than perfect outcome,” says Dr. Rocha.

Surgical electron microscope photograph of the Surgin LASIK blade at 1000X. Key elements to look for are edge consistency and absence of debris, bends or defects.

Surgin

“A blade without defects produces a clean and precise cut. Standard magnification from a surgical microscope cannot detect all defects, but a scanning electron microscope shows all imperfections.” He tests microkeratomes and blades on cadaver eyes. “This refines my understanding of the calibration and settings of the instrument, and allows me to feel comfortable with its functions,” he says. “I aim to obtain adequate flaps and stromal beds in every case.”

Polish blade side edges to remove any metal residue left from the manufacturing process, says Dr. Rocha. “A smooth side edge will reduce the friction between the blade and the microkeratome head, improving the sliding performance and wear characteristics,” he says. “Standard magnification from an operating microscope will detect if a blade side edge has been properly polished.”

Armand Maaskamp, president of third-party blade maker Surgin and holder of four medical device patents, urges surgeons who may not have access to a scanning electronic microscope to visit a university lab to check out the blade. To compare different blades, he suggests you send them to an independent laboratory, which can diagnose quality at 1000X- to 2000X-magnification powers.

Careful Evaluation
After you inspect the blade, be aware what you use to clean it with before it goes on the microkeratome, says Mr. Maaskamp. He says he knows of doctors who examine the blades under a scanning electron microscope, but then apply acetone as a cleaner just prior to using the blades in surgery. “Blade manufacturers and surgeons should use a non-invasive process that does not damage the cutting edge,” says Mr. Maaskamp. “If you were to take a scanning electron microscope picture of a blade in which acid was used to clean it, you are going to see a compromise of the cutting edge.” He says surgeons were regularly cleaning blades with acetone to counter cases of Sands of Sahara. “If you feel you should still clean a blade after a company says it has gone through what it claims is an extensive quality-control process, then you are using the wrong company’s blade,” he says. “There should be no need to clean that blade at that point.”

Cleaning the metal blades after they have been cut and formed to shape is a critical manufacturing step, says J.R. Dennewill, quality assurance manager at third-party blade maker Med-Logics. “The cleaning process has to be thorough, but if it is too aggressive, the delicate blade edge can be damaged.”

Make sure blades are free of all debris, residue, oils and stains from the manufacturing process, says Dr. Rocha. The manufacturer must be able to remove all the materials used to manufacture and cut the blades to size. “Residue includes yellowish or orange stains, oils, skin particles, polishing grit and other remnants that become attached to the blade during the manufacturing process,” he says.

Also, be extra careful opening the blade package, says Mr. Dennewill. The blade carrier (plastic protective package) is an important design issue, he says. “If the package is not easy to open, you can damage the blade edge while opening the blade carrier,” he says. “If the blade carrier opens too easily, the blade can be ejected from it, which damages the blade edge.” He says the amount of force required to open the carrier should be minimal and consistent.

On the Microkeratome
Los Angeles surgeon Uday Devgan inspects a group of blades from the same lot under a scanning electron microscope. “This way if you’re happy with the first few blades, then the rest of the lot is likely to be the same,” he says. His inspection continues after each blade is loaded on to the microkeratome. “Run the blades on the microkeratome and listen for any changes in the pitch of the motor, and any slowing of the oscillations,” he suggests.

By continuously doing a double check of blades right from the box and then on

Surgical electron microscope photo (at 2000X) of a cutting edge of a Med-Logics LASIK blade. Make sure all blades are free of debris, residue, oils and stains from the manufacturing process.

Med-Logics

the microkeratome, Dr. Stulting says blade-related complications in his practice now occur at a rate of less than a half percent. “When we have that rare problem, we put the microkeratome and its blade aside and we take a look at it and try to determine what the problem may have been,” he says. “We have a quality assurance committee that reviews complications, including a blade complication, and tries to determine whether there are patterns, and we fix whatever problems those patterns point to,” he says.

Mr. Dennewill says your technician can damage the blade edge sometimes without knowing it, so a last-minute inspection on the microkeratome head is a worthwhile step. “Inspect both sides of the blade and use the illumination of the microscope light to produce a reflection on the cutting edge surface, which will highlight any damage to the cutting edge,” he says. “If you are using a brand of blades that you have experienced problems with in the past, spend additional inspection time and be liberal with your rejection of the blades in question.”

Generic vs. Originals
At present, there are no peer-reviewed studies comparing different manufacturers’ blade quality. However, several manufacturers are working with LASIK surgeons on studies measuring and comparing outcomes. That report may be available at this October’s American Academy of Ophthalmology meeting.

Dr. Rocha says to best review the different blades, compare the quality and smoothness of the stromal bed  over an extended time period. “Approach every case slowly, reviewing the different features at each surgical step,” he says. “Assess the predicted vs. obtained diameter of the cut, the smoothness of the stromal bed, consistency of the flap thickness and the edges of the flap.”
Dean Burns, marketing manager of refractive products for Alcon, says the firm manufactures blades for its SKBM microkeratome with extremely tight quality control. “Cost is an issue in a declining market,” he says, “but when you look at the cost to manage a patient if you have a complication that is related to the blade, that cost is actually higher than the few extra pennies you would spend for a good blade.”

Mr. Maaskamp says the U.S. Food and Drug Administration makes his company go to great lengths to prove that its blade is safe and effective and cuts within the same tolerances and the same deviations that the original manufacturer’s blade does. He estimates Surgin blades can save surgeons 30 percent or more over the microkeratome manufacturer’s blades.

Dr. Devgan says that you should thoroughly examine all blades, whether they’re third-party or standard. He says he used a company’s microkeratome on a patient with the company’s own blades and he had a blade malfunction due to poor tolerances for that particular lot of blades.

Kansas City surgeon Daniel S. Durrie does not reuse his blades for a second eye on the same patient, but he encourages all surgeons who do to re-inspect the blade between eyes. “Most published literature shows that a blade will be cutting 20-percent thinner by the end of its first cut, and if you use it on the second eye, it will cut even thinner,” he stresses. “You’ll find significant quality changes under the scanning electron microscope.”