EyeWorld India March 2012 Issue

40 EW CORNEA March 2012 Views from Asia-Pacific Focusing on FLAK: Femtosecond technique compared to PK by Maxine Lipner Senior EyeWorld Contributing Editor Considering whether FLAK improves corneal transplant outcomes A stigmatism outcomes for femtosecond laser-assisted keratoplasty (FLAK) are only significantly improved at the 4- to 6-month follow-up period compared to conventional penetrating keratoplasty, according to Winston D. Chamberlain, MD, PhD , assistant professor, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., USA. Results published this past spring in Ophthalmology showed improvement at just the one time point compared to several in an earlier study on this. The goal was to look at the first 50 patients who were done and compare them with 50 others who had very similar pathologies. “We wanted to try to analyze the outcomes to see if the femtosecond technique was actually improving our outcomes,” Dr. Chamberlain said. A prior study published in the September 2009 issue of Ophthalmology had also looked at this but didn’t have as many cases to consider. “They didn’t have the power to analyze the results with similar pathologies in patients who received the conventional surgery,” Dr. Chamberlain said. “I think this was one of the strengths of this study—we were able to do a much stronger comparison between conventional techniques and the femtosecond technique.” Unexpected finding The first finding, which Dr. Chamberlain termed somewhat surprising, was that astigmatic outcomes in this study did not measure up to those in the original investigation. “We only found a significantly different level of astigmatism in the femtosecond laser transplants at 6 months,” Dr. Chamberlain said. By contrast the original study found improvement in astigmatism results with the femtosecond laser at all early time points. A second finding indicated that there was no improvement in best spectacle corrected acuity at any time point that was measured. Dr. Chamberlain thinks that the differences can be attributed to technique variations. “The first study was done by one surgeon with one suture technique,” he said. “We had three different surgeons with two different fellows involved using four different suturing techniques.” He thinks this introduced a variable, which needs to be assessed more. Roger F. Steinert, MD , professor and chair of ophthalmology, professor of biomedical engineering, and director, Gavin Herbert Eye Institute, University of California, Irvine, agreed that technique came into play here. Dr. Steinert, who took part in the original study, thinks that even with femtosecond technology, the surgeon plays an important role. “There were major differences in the way that they did it,” Dr. Steinert said. “The bottom line is no matter whether Choun-ki JOO, MD Professor, Department of Ophthalmology & Visual Science, College of Medicine, The Catholic University of Korea Director, Seoul St. Mary’s Hospital Eye Institute (SSEI) #505 Banpo-dong, Seochu-Ku, Seoul, 137-040, Korea Tel. no. +82-2-2258-7620/7621 Fax no. +82-533-3801 ckjoo@catholic.ac.kr F emtosecond-laser assisted keratoplasty seemed to be the ideal approach at first, although in recent years, we have come across some of its short comings in terms of clinical results. In corroboration with other published data, our hospital data analysis also showed improved astigmatism at only a particular point of postoperative time. Asmany opine, I also feel that surgeons’ skills have an upper hand over any innovative technology. But by adding good technology over fine skills, better surgical outcomes can be achieved. As with keratoplasty, the application of a femtosecond laser is very helpful in achieving desired results. It not only provides a greater wound surface area, which results in better wound integrity and faster healing, but also makes ideal radial alignment markings, on donor as well as recipient cornea. The sutures placed over these markings are equally spaced and with the least angular disparity. Therefore, this technology aids in the success of surgery. In order to achieve the desired clinical results, further research on the postoperative changes in corneal thickness is required, in my opinion. Until now, we have been using the preoperative data for calculating the step depths and designs (top hat/ mushroom/zigzag). These levels can change postoperatively, e.g., if a cornea having bullous keratopathy is edematous, it becomes thinner after transplantation. Donor cornea thickness can vary in storage media and post transplantation. So we need to analyze the accumulated pre- and postoperative data and apply the results for keratoplasty designs in future. To conclude, femtosecond laser technology is proven to be an important tool in the field of keratoplasty, but we need further research in order to achieve truly miraculous clinical results. Editors’ note: Prof. Joo is a consultant for Abbott Medical Optics but has no financial interests related to his comments.