EyeWorld Asia-Pacific September 2016 Issue

September 2016 EWAP refractive 55 Femtosecond laser flap creation in prior RK patients by Maxine Lipner EyeWorld Senior Contributing Writer Study results indicate there is no need to forego femtosecond LASIK in such patients A prior radial keratotomy (RK) usually makes practitioners think twice about creating a LASIK flap with a femtosecond laser. But study results published in the September/October 2015 issue of the Asia-Pacific Journal of Ophthalmology point to the fact that the femtosecond laser can be a viable option, according to Sloan Rush, MD , in private practice, Amarillo, Texas. The results indicated that LASIK flaps were able to be successfully created in 100% of the post-RK patients who were included here, he reported. The investigation was spurred by the fact that many of the patients who underwent RK in the late 1980s and 1990s are now in a situation ripe for retreatment. “As we know, many of our RK patients develop hyperopic regression, so they come back to us years later. Some of them are now in their late 40s and others in their early 50s,” Dr. Rush said. Such individuals are seeking additional refractive treatment because they are now becoming presbyopic and the hyperopic refraction with which they are living has become problematic. While they may have been able to accommodate through this in the past, with the beginning of presbyopia, that is no longer possible, and they want something else done, he explained. “Ideally, we don’t want to offer them a refractive lensectomy, especially if there is no cataract there,” Dr. Rush said. “In my center we prefer not to do PRK because we know in our hands we’re better with LASIK, and PRK can have healing problems and take longer to recover from.” Dr. Rush’s top choice is LASIK, assuming that he can create a safe and successful flap. Femtosecond RK dilemmas While traditionally a manual microkeratome has been successfully used, some practitioners have moved away from these. “Now a lot of us— myself included—have hung the microkeratome on the shelf, and we feel a lot more comfortable using the femtosecond laser,” Dr. Rush said. “We like the flexibility it gives us with controlling the flap depth and the diameter.” The problem in RK patients is that the femtosecond flap doesn’t just lift open; it leaves little stromal bridges that have to be broken apart by an instrument, he explained, adding that in the RK patient, the prior incisions can sometimes be more fragile than the perforated edge left by the femtosecond laser. The result can be what appears to be an 8-slice pizza pie-like flap, Dr. Rush said. There is also concern about evacuation of the air bubbles left by the femtosecond laser, with the worry that in certain circumstances there may be vertical gas breakthrough via an old RK incision. “You open a Some practitioners are hesitant to create a LASIK flap with a femtosecond laser in prior RK patients. Source: John Berdahl, MD A recent study found that femtosecond LASIK can be a viable option for prior RK patients. Source: Uday Devgan, MD whole can of worms for potential complications with epithelial ingrowth or an unstable flap or irregularity when you try to lift it and one of the incisions is filleted open,” Dr. Rush said. However, he has experimented with many different femtosecond laser settings, trying to modulate the way it cuts the flap. “Through our experience, we are aware of settings where we can cut a femtosecond flap and leave no tissue bridges behind—where it cuts completely clean all of the way through,” Dr. Rush said. “This is an ideal setting to have when you have a previous RK eye, so you don’t have to worry about spreading open the incision.” He finds that it then lifts more like a manual microkeratome flap would, with no resistance. Included in the retrospective continued on page 56