EyeWorld Asia-Pacific June 2012 Issue

June 2012 16 EWAP FEATURE Stomping out post-LASIK epithelial ingrowth by Maxine Lipner Senior EyeWorld Contributing Editor AT A GLANCE • Screening for underlying conditions, type of refractive correction, and even the patient’s age can help forestall ingrowth • For enhancements, a technique dubbed flaporhexis can bring ingrowth rates dramatically down • One new possibility for treating ingrowth is use of the YAG laser Innovative ways to curtail cases E pithelial ingrowth is one of those rare things that can affect any surgeon from time to time. From screening and prevention to innovative treatment options, EyeWorld asked leading practitioners to weigh in on this troublesome complication and how to keep it at bay. Prevention in epithelial ingrowth cases is pivotal, believes Neel Desai, MD , Largo, Fla., USA. “Though it is rare, it is unfortunately going to be a more common issue if we’re not careful about it,” Dr. Desai said. “The reason is we’re seeing increased levels of ocular surface disease, and we’re also seeing higher rates of refractive enhancements following cataract surgery.” When treated with LASIK the elderly population, he finds, is more prone to epithelial ingrowth to begin with. Staving off ingrowth From a screening standpoint, Dr. Desai finds that there are some critical things to look for such as dry eye syndrome, basement membrane dystrophy, mechanical lid abnormalities, and the patient’s age. For example, in a younger patient who is going to heal rapidly, a practitioner may readily consider a flap-lift enhancement, but the practitioner may want to steer an older patient away from this. To curtail ingrowth, he also stressed the importance of screening out those with dry eye syndrome. Tests such as LipiFlow (TearScience, Morrisville, NC, USA) or tear osmolarity may spot those patients with subclinical disease before undergoing LASIK. “Things that quantify the level of ocular surface disease or dry eye syndrome that the patient might have would be useful tools in steering us either toward doing a flap-lift enhancement or toward simply doing a lens-based procedure,” Dr. Desai said. The type of LASIK surgery being performed may also play a role, according to Mark Packer, MD , clinical associate professor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Ore., USA. In a study that appeared in the May 2011 issue of Cornea , Dr. Packer and fellow investigators considered the incidence of epithelial ingrowth after LASIK and its correlation with myopic or hyperopic treatment. They found that this is much more common in hyperopic cases with an incidence of 23% versus just 3% for myopic cases. “I think in general the hyperopic anatomy is such that the eyelids tend to be floppier and certainly the corneas tend to be flatter,” Dr. Packer said. “The shape of the eye is different so that there is more likelihood of slippage, which gives you an irregular edge to the flap, and that’s where you can get into trouble.” When relifting the flap in hyperopic cases, Dr. Packer tries to use a slightly higher magnification to make sure that he doesn’t see pieces of epithelium under the flap. He also uses a bandage contact lens the first night after an enhancement to help minimize the chance of flap dislocation. TRICKS FOR AVOIDING INTRAOPERATIVE INGROWTH In keeping ingrowth at bay, Dr. Desai suggested the following: • Avoid giving the patient too many anesthetic drops • Make sure that the anesthetized patient is not sitting around for long periods before treatment • If there’s an epithelial abrasion at the flap edge, brush the epithelium back and place a contact lens • Irrigate just the right amount, making sure that there are no cells underneath the flap or at the edges, but not so much as to swell or thicken the flap • After the flap is down, squeegee any fluid toward the edge to maximize flap adherence In hyperopic cases in particular, Dr. Packer recommended making sure that the suction ring is appropriately sized so that practitioners don’t cut too close to the limbus. When laying the bigger hyperopic flap back down, he suggested carefully examining the margins of the bed and the flap and making sure that you don’t see epithelial material anywhere. Dr. Desai suggested an ovoid flap may be one appealing option, particularly in hyperopic cases. “That seems to allow us to have a wider diameter flap to avoid the ablation zone or the treatment zone or the blend from interfering with the edges of the flap,” he said. Another possibility might simply be to increase the diameter of the flap and shift to a temporal hinge to limit the number of corneal nerve bundles cut, forestalling dry eye, which may predispose patients to ingrowth. How the flap is made may also be an important factor here. “Microkeratomes famously give you a shallow sloped flap architecture, which allows the path of least resistance for those epithelial cells to go straight downhill,” Dr. Desai said. “The femtosecond laser, in particular the IntraLase [Abbott Medical Optics, AMO, Santa Ana, Calif., USA], is one of the other technologies that is allowing us to do either a very steep side cut or a 70- or sometimes an 80-degree side cut.” With the IntraLase, he pointed out it is even possible to do a reverse bevel keystone cut, which locks the flap in and prevents epithelial ingrowth. However, all femtosecond lasers are not the same. “It’s buyer beware in that some femtosecond lasers do still give you somewhat of a sloped flap architecture,” Dr. Desai said. One innovative method for forestalling epithelial ingrowth after a LASIK enhancement is a technique dubbed flaporhexis, developed by Steven E. Wilson, MD, professor of ophthalmology, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio, USA. Dr. Wilson reported on the technique in the January issue of the Journal of Cataract & Refractive Surgery. However, he has been doing the technique since as far back as 1998. With the technique, practitioners mark the edges of the flap. Dr. Wilson uses a 3-mm circle with gentian violet in conjunction with a Sinskey hook. “If you take the Sinskey hook and press it into the epithelium at the limbus, drag it toward the center, you’ll actually feel the flap edge,” Dr. Wilson said. “The Sinskey hook will kind of catch right there and you know that’s the edge of the flap.” Then practitioners can go back and forth