EyeWorld Asia-Pacific June 2011 Issue

23 EW REFRACTIVE June 2011 Hungwon TCHAH, MD Professor, Dept of Ophthalmology, University of Ulsan, Asan Medical Center 399-1 Pungnab-dong, Songpa-gu, Seoul, Korea Tel. no. +822-030103680 Fax no. +822-4706440 hwtchah@amc.seoul.kr T he LASIK procedure has improved since its birth in the late 80s. This procedure seems to be quite safe, these days, when the surgical guidelines are strictly followed. However, there are still complications, especially intraoperative complications which are related to flap creation, although the incidence is very rare—less than 0.6%. Some of these flap-related complications can be serious because they cause corneal opacity and irregular astigmatism and, ultimately, visual disturbance. I believed femtosecond laser flap creation would decrease the incidence of flap-related complications compared with mechanical microkeratome and have used femtosecond laser since 2008 in almost every LASIK cases. So far, there has been no incidence of torn flap or button hole in my practice. Flap-related complications with a mechanical microkeratome occur for various reasons—motor malfunction, rough mechanical blade, and mostly suction loss from suction ring. Asian eyes tend to have smaller palpebral fissures compared with Caucasian eyes. There are some eyes in which the suction ring of a microkeratome or femtosecond laser cannot be applied. Even after application of the suction ring, suction loss can occur rather easily in these small-fissured eyes. When suction loss occurs during flap creation with a mechanical microkeratome, the surgical case should be aborted. If incomplete flap margin is located in the papillary zone, the visual recovery is not guaranteed even after a delayed attempt to recreate the flap. On the other hand, a case can be aborted or a second laser cut can be attempted immediately depending on the situation even after suction loss during flap creation with a femtosecond laser. In almost every case, final visual results are not affected by this incidence. It therefore seems to be safer to use a femtosecond laser than a mechanical microkeratome. I think Asian eyes especially with small fissures may need femtosecond laser flap creation more than Caucasian eyes. Femtosecond laser flap creation also has complications and some complications, such as diffuse lamellar keratitis, have higher incidence compared with mechanical microkeratomes. However, in terms of safety, I think the femtosecond laser is superior to mechanical microkeratome. The learning curve of femtosecond laser flap creation is not very steep so I would recommend this technology, especially, for surgeons in their early stage of LASIK, for safety reasons. Many LASIK surgeons are still mainly using mechanical microkeratomes. In South Korea, approximately 40-50% of surgeons are using a mechanical microkeratome routinely and the ratio of mechanical microkeratome users is even higher in Europe and the US. The higher cost of purchasing and maintaining a femtosecond laser and the relatively low complication rate with current mechanical microkeratomes in experienced hands might be the reasons for the continued use of mechanical microkeratomes. I hope the cost related to the femtosecond laser decreases in the near future so that every LASIK surgeon can have access to the current technology of femtosecond laser. Editors’ note: Prof. Tchah has no financial interests related to his comments. of any issues that occurred with the IntraLase technology. “We kept a log of interesting and unusual things that happened that we would call intraoperative complications,” he said. “Then we analyzed the cases and the results from these.” When Dr. Davison reviewed the results with the IntraLase from August 2002 through July 2009, he found that there were very few issues, with just 11 complications over the years. “We didn’t have any vision-threatening complications,” he said. “The most common issue was suction break.” This was dealt with in a very routine manner. “We have a team of technicians who do laser all the time and they know how to reapply it. We could go ahead and reinitiate it, like it’s recommended, and it worked fine,” Dr. Davison said. “We didn’t have to cancel patients or have them come back like we do with a mechanical microkeratome.” Dr. Davison had one patient, who had very unusual eyes, who was problematic. “I had one patient who had very interesting eyes because they seemed to absorb the laser energy a little bit more than most and have a little bit more carbon dioxide gas accumulate in the interface,” he said. “This probably interfered with how the laser energy was absorbed.” Dr. Davison found that he could barely get the patient’s flaps elevated. After consulting with his partner, Dr. Davison decided to reapply the laser. “We did that and then with great effort I was able to elevate the flaps and do the case,” he said. “It took me about 11 minutes to raise one flap and 4 minutes to raise the other, while usually it takes about 10 seconds, so it was a huge effort, but it was doable.” Wave of the future Using the IntraLase instead of mechanical microkeratomes is akin to converting from extracapsular cataract surgery to phacoemulsification, to Dr. Davison’s way of thinking. “It took 20 years for that conversion to be complete but now pretty much no one does extracaps and everyone does phaco,” he said. “I think that it’s going to be the same thing with this because it’s superior technology.” Dr. Davison acknowledged that the IntraLase technology has its issues, including expense, but sees it as a worthwhile investment. “We have to purchase technology that gives better results and provides better patient care,” he said. “We don’t have a valet parking service, but we have this because I think that it does provide better patient care over the long term.” He pointed out that anyone can have problems with LASIK. Given the procedure’s elective nature, he sees this as putting more pressure on the surgeon. “Everyone thinks that LASIK is an easy thing, but there is a certain amount of anxiety when you sit down with someone with an otherwise normal eye and you’re going to do something to it,” Dr. Davison said. “You take on a certain amount of risk with that.” Overall, Dr. Davison sees the femtosecond technology as an excellent addendum in forestalling LASIK complications. “If you can acquire the technology at a reasonable price and if you can create a discipline to use the technology to avoid catastrophic complications, then it’s going to be a good thing,” he said. EW Editors’ note: Dr. Davison has financial interests with Alcon (Fort Worth, Texas, USA/Hünenberg, Switzerland). Contact information Davison: jdavison@wolfeclinic.com