Eyeworld

EW FEATURE 38 cedure is indicated for any potential refractive surgery patient with pres- byopia who hasn't developed cataracts and especially if the patient also has astigmatism because ex- cimer laser ablation presents the most accurate approach to astigma- tism correction. PresbyLASIK can be preformed in eyes previously im- planted with a monofocal IOL. "We did research on [presby- LASIK] and found that in the hyper- opes that we treated, we got very good results," Dr. Jackson said. But without approval in North America, Dr. Jackson said what is happening primarily is surgeons are trying different presbyLASIK tech- niques with an off-label approach. Meanwhile, surgeons in Europe are performing much more presby- LASIK, and there they have more flexibility with their lasers, Dr. Jackson noted. There are a number of programs that have been developed to do pres- byLASIK in Europe, he said. Some surgeons create a central zone for near vision, surrounded by a periph- eral zone for distance vision (central presbyLASIK); others create a central zone for distance vision and the pe- riphery is ablated for near vision (pe- ripheral presbyLASIK). Still others are treating the dominant eye for distance and the non-dominant eye with a sort of blended vision—it's different from monovision in that they have more range for distance and near created by altering the spherical aberration, Dr. Jackson ex- plained. "There are a number of ap- proaches that surgeons are using, but [presbyLASIK] certainly does en- hance near vision," he said. In fact, studies in Europe have shown presbyLASIK to provide good distance and near vision. Some sur- geons have reported patients achiev- ing bilaterally 20/20 or better for distance and J3 or better for near with a majority of satisfied patients. Experts note that careful patient se- lection is key for good outcomes. If patients are unsatisfied, pres- byLASIK is reversible with a wave- front laser treatment. PresbyLASIK vs. monovision LASIK Even with the positive results the procedure has produced, however, some surgeons have fairly strong feelings against it. "I think there are better ways to treat presbyopia than presbyLASIK," said D. Rex Hamilton, M.D., associ- ate clinical professor of ophthalmol- ogy, and director, Laser Refractive Center, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Ange- les. By creating a multifocal cornea, function is traded for quality of vi- sion, and by performing LASIK or PRK, tissue is permanently removed from the cornea, he explained. Dr. Hamilton said he thinks monovision LASIK is a better option, and ultimately a lens-based option is the best as it gets at the root of the problem—the natural lens's loss of accommodation and overall stiffen- ing. On the other hand, if a multifo- cal cornea is created, once a cataract develops later in life requiring lens surgery, the surgeon then has to deal with a cornea that's somewhat com- promised optically. There are also some downsides to presbyLASIK, the biggest of which, as with monovision LASIK, is the temporal nature of the treat- ment approach. As presbyopia pro- gresses over time, the surgical effect becomes less optimal. Still, according to Dr. Jackson, as North America tends to be a bit more conservative than Europe, presbyLASIK, if FDA-approved, would be embraced as part of a two- stage approach. "I think a lot of surgeons would do [presbyLASIK] first and then, when the patient really does have a cataract, move to cataract surgery," he said. If presbyLASIK receives FDA ap- proval, Dr. Jackson said it will be very popular because some surgeons are convinced of its value and are al- ready performing it off-label. Shaping without dissecting A different treatment approach from presbyLASIK, INTRACOR makes use of the femtosecond laser to create multifocality in the cornea. Sur- geons focus the laser beam at a spe- cific depth without dissecting the corneal surface, said Mike P. Holzer, M.D., associate professor and direc- tor, refractive surgery, University of Heidelberg, Germany. The procedure changes the shape of the cornea, making the central part of the cornea a bit steeper, essentially creating a magni- fying glass in front of the eye, he said. Without cutting open the corneal surface, as would be done for a flap procedure, the surface re- mains untouched and there is no risk for infection because there's no way bacteria can get into the cornea, Dr. Holzer explained. This results in an extremely quick recovery time and no risk of severe side effects. In fact, patients achieve results within the first day post-op, he said. In near reading tests, patients typically gain between four and five lines of near visual acuity. With a follow-up period of more than 2.75 years, Dr. Holzer said patients showed no change in the shape of the cornea or in the refraction. This shows the procedure is stable. "We had some discussions that maybe this biomechanical change that we induce with the femtosec- ond laser will change later on and then the outcome will not be as it should, but that's not the case. We can say that after 1 week, the out- come is achieved and stable over time," he said. In fact, patients who don't achieve the expected results after 1 week typically do not improve. "You have your final results very early," Dr. Holzer said. What has been observed are differences in near reading ability gained between patients, Dr. Holzer noted. Some patients can read the finest print easily, while others can read or recognize things in the near distance but find it stressful to read a book for an hour and require a bit more near vision. Therefore, this is one area of uncertainty. Selecting the right patients The typical INTRACOR patient has not developed cataracts, although it is possible for a post-cataract surgery patient to have the procedure. IOL calculation after INTRACOR is not a problem, Dr. Holzer said. The best candidate for INTRA- COR is a patient with no further oc- ular disease, with a near add of 2.0 D or more, and with a distance refrac- tion that should be between +0.5 D and +1.25 D spherical equivalent. The subjective cylinder should not be higher than half a diopter, he said. February 2011 PRESBYOPIA June 2011 Corneal continued from page 37 but Synchrony, which AMO ob- tained when it acquired Visiogen in 2009, is currently in front of the FDA and could gain approval this year or next. Synchrony is a dual-optic ac- commodating IOL that uses a pre- loaded disposable injector allowing for controlled implantation into the bag. Currently, the incision needs to be around 3.8 mm, which does in- crease the chance of surgically in- duced astigmatism (SIA). Studies have shown that SIA stabilizes within .5 D by 3 months post-op. Furthermore, making a circular and centered capsulorhexis of less than 5 mm is crucial; if it's too big the lens won't be retained in the bag. "There is no question the Synchrony accommodates to a very acceptable degree," said Dr. Hovanesian. "The challenge it will face is that not every surgeon is ready to implant a lens this mechan- ically complex. The company has done a brilliant job of creating an injector system that, at the time of approval, will probably go into an incision less than 3 mm in size, but you have to have some faith that the lens will unfold the way it's designed to. Not all surgeons are ready for that. It will be well suited for fem- tosecond laser surgery." Dr. Dougherty agreed. "From what I understand, it's a much more difficult surgery. For the average sur- Next-generation continued from page 36 geon, it's going to be a much more challenging lens." All of this, of course, is specula- tion. The technology is sure to de- velop and evolve between now and when most of these lenses are ap- proved. "Right now we can only talk about these lenses conceptually and what we expect to see," said Dr. Hovanesian. "The new lenses are more complicated in their design and implantation, but will probably deliver accommodation that is much closer to what nature did in a young, healthy eye." EW Editors' note: Dr. Dougherty has a financial interest with Lenstec. Dr. Hovanesian has financial interests with AMO and Bausch & Lomb. Dr. Alió has financial interests with AMO, AkkoLens International, and NuLens Ltd. Contact information Alió: jlalio@vissum.com Dougherty: flapzap@gmail.com Hovanesian: drhovanesian@harvardeye.com continued on page 41

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