Eyeworld

MAR 2012

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

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90 EW FEATURE February 2011 Refractive March 2012 Stomping out post-LASIK epithelial ingrowth by Maxine Lipner Senior EyeWorld Contributing Editor Innovative ways to curtail cases E Q pithelial ingrowth is one of those rare things that can affect any surgeon from time to time. From screen- ing and prevention to innovative treatment options, EyeWorld asked leading practitioners to weigh in on this troublesome complication and how to keep it at bay. 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 Prevention in epithelial in- growth cases is pivotal, believes Neel Desai, M.D., Largo, Florida. "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 in- creased levels of ocular surface dis- ease, and we're also seeing higher rates of refractive enhancements following cataract surgery." When treated with LASIK the elderly popu- lation, he finds, is more prone to ep- ithelial ingrowth to begin with. Staving off ingrowth From a screening standpoint, Dr. Desai finds that there are some criti- cal things to look for such as dry eye syndrome, basement membrane dys- trophy, mechanical lid abnormali- ties, and the patient's age. For example, in a younger patient who is going to heal rapidly, a practi- tioner may readily consider a flap-lift enhancement, but the prac- titioner 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, N.C.) or tear osmolarity may spot those patients with sub- clinical 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 steer- ing 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, M.D., clinical associate professor of oph- thalmology, Casey Eye Institute, Oregon Health & Science University, Portland. In a study that appeared in the May 2011 issue of Cornea, Dr. Packer and fellow investigators con- sidered the incidence of epithelial ingrowth after LASIK and its correla- tion with myopic or hyperopic treat- ment. 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 flop- pier 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 hy- peropic 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 disloca- tion. In hyperopic cases in particular, Dr. Packer recommended making sure that the suction ring is appro- Monthly Pulse Keeping a Pulse on Ophthalmology uestions 2 and 3 convey an important message that is not obvious at first glance. Epithelial ingrowth that required treatment was reported to occur about 1-5% of the time for 30% and greater than 5% of the time for about 5% of LASIK surgeons. Question 3 shows us that roughly half of the surgeons use the femtosecond laser and the other half use the microkeratome. When we further cross-referenced the answers to questions 2 and 3 (not shown in the data), we found the incidence and frequency of ingrowth after en- hancement was reported in similar proportions for surgeons that used the microkeratome, the regular side-cut femtosec- ond laser, and the inverted side-cut femtosecond laser. What does this tell us? Neither femtosecond laser nor inverted side-cut protect us from epi ingrowth after flap lift. It is the flap lift itself that is responsible for ingrowth regardless of the technology used. Surgeons interested in reducing or eliminat- ing ingrowth should consider PRK enhancements rather than flap lifts. The majority of respondents to question 7 prefer to leave 300-350 microns of residual bed. We know from sev- eral studies that the LASIK flap provides no corneal structural integrity, so the amount of residual bed logically should be the same amount of tissue that surgeons prefer to leave post-LASIK. However, the survey found this number to be more commonly 250-300 microns. Therefore, it appears that surgeons tend to be more conservative with regard to resid- ual bed with PRK than with LASIK, perhaps because there are other factors that influence their decisions aside from the residual bed thickness alone such as the original corneal thickness, the age of the patient, or subtle asymmetry in the topography. Louis Probst, M.D., refractive editoral board member T he response to question 1 shows the excitement for a technology that holds the potential to help improve pa- tient outcomes with cataract surgery by standardizing and improving the consistency of the corneal incisions and capsulorhexis formation. Responses to question 2 are con- sistent with published data that shows that the rate of ep- ithelial ingrowth is low, typically less than 5% of LASIK enhancements. The response to question 3 illustrates that of the surgeons performing LASIK, about an equal number re- port using a femtosecond laser at 32% versus 28% who continue to use a mechanical microkeratome. It would ap- pear that the rate of epithelial ingrowth is not greater in ei- ther group of microkeratome use; most likely, it is related to other risk factors for epithelial ingrowth such as lifting the flap versus surface ablation to perform an enhancement. The survey responses to me reflect the increased use of more advanced IOL calculation formulas to help improve post-op refractive outcomes as more premium IOL technolo- gies such as toric lenses and presbyopia-correcting lenses are used. Y. Ralph Chu, M.D., refractive editoral board member Question 1 Question 5

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