Eyeworld

AUG 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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August 2014 by Ellen Stodola EyeWorld Staff Writer W ith the femtosecond laser being explored for a multitude of uses, indications for the technology in glaucoma surgery could be a possi- bility. Many factors are still being evaluated, including cost and when the laser can be applied. Malik Kahook, MD, Slater Family Endowed Chair in Ophthalmology, and professor of ophthalmology, University of Colorado School of Medicine, Aurora, Colo.; and Michael S. Berlin, MD, professor of clinical ophthalmology, Jules Stein Eye Institute, University of Califor- nia, Los Angeles, and director of the Glaucoma Institute of Beverly Hills, discussed the possibilities for femtosecond laser-assisted glaucoma surgery (FLAGS). How it would work Dr. Berlin has been exploring ap- plications using femto lasers in a variety of glaucoma surgeries for a number of years. Because femto laser wavelengths are corneal transmissi- ble, FLAGS procedures could be ap- proached transcorneally, ab interno, in a manner similar to femto cata- ract procedures, and ab externo, in a manner similar to corneal lamellar flap procedures, he said. Applications for the femto laser ab externo include creating trabe- culectomy flaps, non-penetrating procedure flaps, near-perforating deep excisions under flaps, removal or thinning of trabecular meshwork and the inner wall of Schlemm's canal, and creating suprachoroi- dal fistulae, as the sclera, like the cornea, can be almost transparent to these wavelengths, targeting tissues by controlling the depth of focus. Applications for ab interno proce- dures include an ELT (excimer laser trabeculostomy) equivalent using docked gonio lens delivery sys- tems, for creating full thickness or near full thickness scleral windows for trabeculectomy equivalent ab interno procedures, and for creating suprachoroidal fistulae. "Femtosecond lasers have the advantages that they are both cor- neal transparent and almost scleral transparent and can be used on any of the tissue that we want to target in glaucoma by controlled focusing from the inside or the outside," he said. "FLAGS just requires the correct docking and scanning devices to en- able this to happen." Performing an excimer laser procedure to remove outflow obstruction in glaucoma and relieve pressure or using a femto laser could affect similar outcomes as it is almost as atraumatic. Since the femto laser is corneal transparent, a visible wavelength can pass through the cornea with a large optical aperture beam so the energy does not injure the cornea. With the beam focused onto a small optical aperture to micro-photodis- rupt the target tissue, in this case trabecular meshwork, the pattern of this photodisruption would effec- tively create an opening, Dr. Berlin said. Dr. Kahook said that currently the femtosecond lasers that are used in both cataract and cornea surgeries are optimized specifically for those particular tissues. "FLAGS would require modifications to the system, which would be readily achievable with some effort and time," he said. Another possibility for using the laser in glaucoma surgery would be to combine it with femtosecond la- ser-assisted cataract surgery (FLACS) so that the trabecular meshwork could be targeted after the cataract surgery is complete. "The trabecular meshwork can be removed, or targeted holes can be created in full thickness fashion to enhance outflow of aqueous hu- mor," Dr. Kahook said. "An alter- native would be to create a partial thickness intrascleral channel that would receive aqueous humor from the anterior chamber and allow it to drain away through the sclera, thus decreasing IOP." He added that there are a number of potential applica- tions for FLAGS, like assisting in scleral flap formation and creating novel geometries in ocular tissues to enhance implantation of devices. Benefits of FLAGS Benefits of using the femtosecond laser in glaucoma surgery are similar to those associated with using the technology in cataract surgery. These include enhancing precision of surgery and hopefully enhancing outcomes by decreasing surgical time and obviating the need for excessive tissue manipulation, Dr. Kahook said. "FLAGS also has the potential to make the use of femtosecond lasers for cataract surgery more econom- ical for practices by allowing the device more utility across different diseases outside of refractive sur- gery," he said. "If there are more ap- plications for a given laser, practices are more likely to be able to afford the costs associated with buying and maintaining these expensive systems." Ideal patients A number of patients could benefit from this technology, Dr. Kahook said. "Any glaucoma patient who is undergoing combined cataract and glaucoma surgery could potentially benefit from a combined FLACS/ FLAGS platform," he said. "In addi- tion, standalone FLAGS might be an option, although the economics of this will need to be addressed." Dr. Berlin noted that FLAGS applications have the potential to become useful for much of the glau- coma surgical procedure spectrum, once dedicated delivery systems have been developed. "Because you can use these lasers to create precise, near full thickness openings with far less tissue trauma than current blade 52 EW GLAUCOMA Femto for glaucoma August 2014 W ith the growing popularity of femtosecond laser-assisted cataract surgery, it is natural that investigators would attempt to find uses for the femtosecond laser in glaucoma surgery. But using new technology to solve old problems may require discoveries that are far from obvious and take many years. When the vulcanization of rubber was developed, it took 60 years before rubber was used on the soles of shoes. Hopefully, it won't take that long for investigators to find ways that the femtosecond laser can be used to improve glaucoma surgery. In this month's "Glaucoma editor's corner of the world," Malik Kahook, MD, and Michael Berlin, MD, discuss the potential uses of the femtosecond laser in glaucoma. Reay H. Brown, MD, glaucoma editor procedures, they enable trabeculec- tomy-like procedures in which very low pressures can be achieved with wounds that have less likelihood of scarring closed," he said. With the femtosecond laser, surgeons can create a variety of different tissue removal shapes and depths, he said. The femtosecond lasers will eventu- ally have applications in both MIGS patients and in those patients who require greater pressure lowering. Additional points Dr. Kahook said that he would con- sider using FLAGS in his practice if it allows for more efficiency in the operating room and if it "seamless- ly couples" with both FLACS and operating room flow. However, there are things to consider when incor- porating the femtosecond laser into a practice. "We are still in the early stages of adopting FLACS in oph- thalmology, and FLAGS will benefit from the lessons learned as we move forward," he said. The financial burden will be a big factor when introducing femto- second laser-assisted procedures into the practice because the lasers are expensive and require high mainte- nance fees. "It will be necessary to decease the costs of the hardware as well as the one-time docking unit fee that exists today," Dr. Kahook said. "One way to make the economics more reasonable for a greater number of practices is to increase the utility of these lasers across multiple surgical procedures such as glaucoma and retina surgery." Currently, FLAGS is still in the exploration stage, Dr. Berlin said. "The devices that are used for corneal incisions and femtosecond cataract surgery can be used today with minimal modification for the ab externo procedures," he said. "Ab interno procedures, however, will require more technical development and engineering." EW Editors' note: Drs. Kahook and Berlin have no financial interests related to their comments. Contact information Berlin: Berlin@ucla.edu Kahook: malik.kahook@gmail.com Glaucoma editor's corner of the world

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