JUL 2013

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

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44 EW FEATURE February 2011 Cataract challenges July 2013 Calculating IOL power in post-RK eyes by Michelle Dalton EyeWorld Contributing Writer AT A GLANCE • Measuring corneal power in the post-RK patient is easier with standard devices. • Multifocal lenses can be an option, but only if vision fluctuation is minimal throughout the day. • Post-RK eyes with irregular astigmatism do better with monofocal lenses. • The more RK incisions, the longer the post-cataract time to refractive stability. Some aspects of calculating IOL power in these eyes are easier than it may seem, experts say I n the mid 1980s and early 1990s, radial keratotomy (RK) was a popular means to reduce or eliminate the need for spectacles, but it was gradually phased out in favor of LASIK and PRK. The number of incisions can range from four to 32 in post-RK patients, creating a challenge when these same patients present for cataract surgery. The good news? ÒItÕs actually easier to measure corneal power in the post-RK patient than in the postlaser vision correction patient if you use standard devices,Ó said Samuel Masket, MD, in private practice, Advanced Vision Care, Los Angeles, and clinical professor, University of California, Los Angeles. ThatÕs because in the RK eye, both the anterior and posterior surfaces changed in unison, Òso reading these with standard instruments gets us much closer to the true value of the cornea.Ó Although no instrument can read the very center cornea, extrapolating data from all the other curvatures Ògets us pretty close.Ó Dr. Masket firmly believes the post-RK eye Òis such a moving target, a multifocal lens should not be consideredÑit will fail unless we achieve absolute or near emmetropia.Ó He noted that the refraction can change from morning until evening and there may be progressive hyperopic shift over time. Barbara Bowers, MD, in private practice, Innovative Ophthalmology, Paducah, Ky., disagreesÑsheÕll bring these patients in at several different times throughout a day Òand if the vision is fluctuating a little bit, IÕll consider a multifocal. If theyÕre fluctuating drastically between the morning and afternoon readings, IÕll Monthly Pulse O ur latest survey addresses challenges that every anterior segment surgeon faces when planning cataract surgery, especially those cases that may be slightly out of the ordinary. In the setting of small pupil, almost 60% advocated the use of not one but multiple types of pupil expansion methods, including stretching, hooks, and rings. Only 4% of surgeons elected to operate through the small pupil. The second scenario polled was dense cataracts and the potential for femtosecond laser assistance. More than half of respondents believe the femtosecond laser to be unnecessary for dense cataracts, while 34% of respondents would like to have a femtosecond laser to assist with dense cataracts. Also of note is that more than 11% of respondents are already using the femtosecond laser to help with their dense cataracts. The third question in the survey addressed cataract in the setting of possible macular disease. The overwhelming response shows the desire of surgeons to get macular OCT whenever macular disease is already present (46.5%), in the Cataract surgery on a post-RK eye tell them point-blank a multifocal lens will make them miserable.Ó Dr. Masket uses four or five devices to find the flattest Ks, and those are the readings heÕll use for IOL calculation. Astigmatism is an essential component to evaluate in these eyes, said Barry Schechter, MD, in practice, Florida Eye Microsurgical Institute, Boynton Beach, Fla. ÒWeÕve had some very nice results with toric IOLs in RK patients who have varying amounts of regular astigmatism,Ó he said. ÒYou want to look for wound gaping. If the wounds have healed nice and tight, youÕre more likely to get a very stable postop refraction after time, but if you see some gaping, youÕve got the potential for refractive surprises.Ó If thereÕs Òvery irregular astigmatism,Ó Dr. Schechter advises against a toricÑÒyou just have to go with a Keeping a Pulse on Ophthalmology setting of refractive cataract surgery (28%), or even with any cataract surgery (16.7%). Less than 9% of surgeons polled report that they never get macular OCT on their cataract surgery patients. The last question in the survey addressed the confidence level with which we use current formulas and technologies for assessing IOL power in the patient with previous corneal refractive surgery. When surgeons were asked about their level of confidence with current formulas and technologies, a full 72.6% stated that they were somewhat or very uncertain about those technologies for choosing IOL power. Only 27.4% stated that they felt confident choosing an IOL power in the cataract patient with previous corneal refractive surgery. These survey results suggest that as sophisticated as cataract surgery is today, we continue to face new challenges and opportunities for improvement. Saras Ramanathan, MD, cataract editorial board member

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