EyeWorld Asia-Pacific June 2014 Issue

28 June 2014 EWAP FEAturE later during subsequent steps in the procedure even though it was made perfectly with the laser. This suggests a possible problem related to structural integrity of the femto-created rhexis,” Dr. Safran said. He said that at two separate centers investigators had about a 2% tear-out rate with the Catalys laser (Abbott Medical Optics, Santa Ana, Calif., U.S.), and at a third they had a 2.9% tear-out rate with the LenSx laser (Alcon, Fort Worth, Texas, U.S.). This was in contrast to a 0.12% tear-out rate with the manual technique. “If you’re a very good surgeon you might have a tear-out rate of 1 in 1,000 or 1 in 2,000,” Dr. Safran said, adding that in this study the rate of manual tear-out was 1 in 822. “For me, about every 5 years I might see a radial tear. They’re exceedingly rare. It appears that the use of the laser may significantly increase the possibility of this occurrence.” Peter E.J. Davies, MD , Newcastle, Australia, who was an investigator for this study, recalled that in his first 50 cases using the femtosecond laser, everything went well. “But then I had a list where I had two posterior capsule ruptures in a row,” Dr. Davies said. “In my entire surgical career I have never ruptured two capsules on a list.” Dr. Davies teamed with Brendan Vote, MD , University of Tasmania, to take a look at how the incidence of anterior capsular tears compared with the manual and femtosecond approaches in approximately 1,600 patients. It was the first large comparison study of the two techniques. The surgeons were treating real-world cataracts, he said, and not performing best-case clear lens extractions. “Our anterior capsule tear rate was 15 times higher with the femtosecond laser,” Dr. Davies reported. “We had far more tears when we used the laser than when we tore the capsule by forceps.” Investigators examined what was going on with the capsules. “We published the world’s first electron microscopy images of a human capsule cut by the femtosecond laser using three laser brands,” Dr. Davies said. “With each brand of the laser, there is a very irregular margin, aberrant misfiring, and rows of laser shots that are fired in the wrong place, and there are divots in the capsule that aren’t there when the capsule is torn with forceps.” The images are very different from the low magnification images of pig eyes that had originally helped to reassure him on the femtosecond’s safety. “I feel I was misled by the porcine images I saw initially,” Dr. Davies said. “I would not have purchased the technology if I had seen images like the ones we published. How can such irregular capsulotomies be as strong?” Both the manual and femtosecond images in these pig eyes looked the same, he recalled. However, there is a big difference between human and pig eyes. “A dead pig capsule is thick and hard, so it’s different from a human capsule, and these eyes do not move,” he explained. When the femtosecond laser docks onto a human eye, he said, it does not hold the eye completely. Some misfiring due to movement is unavoidable, with packets of laser light 200 micrometers long being fired, he said. “If the eye moves, there is no way a computer is going to detect the movement and signal the laser to change its firing or stop it because the light has already released,” he noted. “I believe that intuitively, the capsule is not going to be as strong if it’s cut by a micro-postage stamp mechanism of mini explosions,” he said. “I think our clinical data supports that.” “Most importantly, in our data, there is no difference in visual results or refractive outcomes between the laser and manual groups,” Dr. Davies said. “We have more than 1,000 patients in each group now. “A common argument for the laser is that the results improve beyond the learning curve. We did not observe a learning curve. The complications kept occurring. We feel there is a fundamental issue of capsule strength that has not been addressed with good quality studies. “For now, our paper abolishes the concept of universality of benefit for all surgeons. The laser did not benefit our patients, and cannot be considered the gold standard until large, good quality studies are done,” Dr. Davies said. “We have 6-month data that does not show significant corneal benefit either.” The 6-month data is being prepared for publication. Dr. Safran pointed out that even if you assume the laser is more efficient, it’s only cost effective for the doctor if the patient pays for it. “No doctor is going to want to take [US]$500 out of his fee,” he said. In addition, there are click fees and maintenance costs. “The problem is you cannot charge a patient for a ‘golden scalpel.’ As a result, it comes down to charging patients for limbal relaxing incisions, which many patients don’t need, and others are better served with a toric IOL,” he said. Overall, Dr. Safran views the push for the femtosecond laser for cataract surgery as marketing driven. “I don’t see the technology as a springboard—I see it as a crutch,” he said. “What I’m looking for is a trampoline, something that’s going to help me jump higher, go further, do better—not something that’s going to automate and reproduce what I can already do.” EWAP Reference Abell RG, Vote BJ. Cost-effectiveness of femtosecond laser-assisted cataract sur- gery versus phacoemulsification cataract surgery. Ophthalmology 2014;121(1):10-6. Editors’ note: Dr. Davies has no financial interests related to his comments. Dr. Safran has financial interests with Bausch + Lomb (Rochester, NY, U.S.) and Heidelberg Engineering (Heidelberg, Germany). Contact information Davies: pejd@bigpond.net.au Safran: safran12@comcast.net No - from page 26