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The WaveLight FS200 laser has a different path for gas bubbles, management that has a positive effect on corneal biomechanics, and smooth integration in an all-laser LASIK workspace O paque bubble layer (OBL)—the collection of gas bubbles in the intralamellar space after femtosecond application —can interfere with pupil tracking, iris registration, and other LASIK- related procedures. The WaveLight FS200 femtosecond laser (Alcon, Fort Worth, Texas) evacuates such bubbles in an ingenious way. The mechanism by which the bubbles are evacuated by the eye is different from the IntraLase (Abbott Medical Optics, Santa Ana, Calif.). The IntraLase recommends creation of a pocket and incarcerating these bubbles deep into the tissue. The FS200 laser makes use of a canal that comes out to the surface of the eye, so bubbles can be evacuated out of the eye. In their book Management of Complications in Refractive Surgery, editors Jorge L. Alio, M.D., and Dimitri T. Azar, M.D., explained that early or hard OBL occurs when femtosecond pulses "initially placed in the cornea have no space avail- able, and water vapor and carbon dioxide produced have nowhere to go. Early or hard OBL can block subsequent pulses and lead to uncut or poorly cut tissue, making flap lifts more difficult." In late OBL, gases produced travel into intralamellar spaces and can make flap lifts difficult, they reported. Ella G. Faktorovich, M.D., in Femtodynamics: A Guide to Laser Setting and Procedure Techniques to Optimize Outcomes with Femtosecond Lasers, further explained that OBL, which can interfere with excimer laser tracking and iris registration, may take as long as 30-45 minutes to clear—quite a long time consider- ing the speed at which LASIK is performed nowadays. With the FS200 laser bubble management system a surgeon can potentially have a bubble-free flap if the canal is the right length. In using the FS200 laser, a slightly longer canal allows for opti- mal release. Also, when centering the suction ring on the eye, it's good to leave more sclera showing superi- orly where the hinge is so there is more room to release these bubbles. It is advisable to make the length of the canal come right up to the edge of where the applanation is (typically this is around where the limbal vessels are located). OBL can still occur despite the use of the canal, but when this happens, surgeons should evaluate if they are taking the canal length out to the edge of the limbus and appla- nation meniscus. It's a little bit of an art and a science. When it is done properly, the surgeon should see bubbles moving through the canal. That's the ideal situation. Surgeons also can easily program the channel length with the FS200 laser. The only issue is, how long should they make it? Although it's hard to say exactly, take it at least out to the sclera vessels and where the edge of the meniscus ends. Biomechanics of the FS200 laser are improved in other ways as well. There is a Beam Control Check, for example, which takes only 10 seconds. This measures the variance of the PI glass and change in hydra- tion and temperature that could lead to changes in flap thickness. Making sure there is a relatively thin flap of uniform thickness will ensure few biomechanical effects on the cornea. The Beam Control Check might make a difference in the accuracy of flap creation, and today that can be measured by doing OCT and other types of measurements. In 2007, my colleagues and I published research observing wave- front aberrations created after flaps that were made with femtosecond lasers versus microkeratomes. Because of the uniformity of the femtosecond laser flaps, there were fewer aberrations created with these in comparison to two of the most popular microkeratomes. I look forward to publishing new research on the FS200 laser comparing it to other femtosecond lasers. Currently I am collecting data and plan to release results after one more year. In the meantime, I am pleased by the convenience of the FS200 laser. It's nice to have the excimer laser directly coupled with the fem- tosecond laser with the same bed. When I finish with the flaps, the bed automatically moves over to the excimer laser where I lift the flaps and go. This saves a step, and in the future, the two lasers will actually "talk" to each other in terms of information to further integrate the two components. I especially look forward to when topographic and wavefront analysis can be linked up with laser outcomes to get better nomograms and better outcomes. That is the goal for the future. Dr. Krueger is medical director, Department of Refractive Surgery, Cole Eye Institute, and professor of ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio. Contact information Krueger: Krueger@ccf.org EW Chicago 2012 5 The femtosecond that releases bubbles with ease by Ronald Krueger, M.D. Figure 1: The appearance of the FS200 flap with the canal and hinge rotated to an oblique axis, which can be set at any orientation Source: Ronald Krueger, M.D. New technologies enhancing patient outcomes " With the FS200 laser bubble management system a surgeon can potentially have a bubble-free flap " Ronald Krueger, M.D.

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