EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/82503
September 2012 Refractive cataract surgery February 2011 EW FEATURE 61 Managing post-op refractive surprises by Michelle Dalton EyeWorld Contributing Writer Knowing what may cause them, how to prevent them, and how to treat them are the keys to ensuring a positive outcome P ost-cataract refractive sur- prises are not completely unavoidable, but under- standing what the risk factors are and how to treat the patient when they happen can ease surgeon stress, said Audrey R. Talley Rostov, M.D., in private practice, Northwest Eye Surgeons, Seattle, and William B. Trattler, M.D., director, Cornea, Center for Excellence in Eye Care, Miami. The duo presented on the topic during this year's ASCRS•ASOA Symposium & Congress. "Because of our patients' under- standable desire for excellent out- comes, we need an entirely different level of pre-operative preparation and care than was common even 10 years ago," said Douglas D. Koch, M.D., professor and the Allen, Mosbacher, and Law Chair in ophthalmology, Cullen Eye Insti- tute, Baylor College of Medicine, Houston. "Fortunately, because we've got better diagnostic tools, we're able to better counsel those patients who are at a higher risk for refractive surprises." Among the variables that may result in a refractive surprise are: corneal disease, very long or very short axial lengths, and disagree- ments in measuring the axis of astig- matism. Co-existent diseases such as pterygium and Fuchs' dystrophy can also be risk factors. Be aware "Major risk factors for ending up off target include previous refractive surgery of any kind," Dr. Trattler said. Dr. Talley Rostov alerts every patient who has had previous refrac- tive surgery that because the cornea has been altered, the patient's initial outcomes may not be desirable, "but I let [the patient] know we know this might happen, and we'll plan for it and fix it down the road." She said most patients fare well, but for those who do not, the preemp- tive alert helps with patient satisfac- tion even while the visual outcomes are still being addressed. "Keratoconus is another major risk factor," Dr. Koch said. "It's something we can detect with a topography and another reason that topography in my practice is manda- tory for all patients—not just reserved for premium IOL patients." Topography can also be used to identify other corneal conditions, including anterior basement mem- brane disease, which can adversely impact cataract surgery results as well, Dr. Koch said. "The quality of vision in those eyes is 'off' after surgery." High myopes are also at in- creased risk, Dr. Talley Rostov said. Likewise, if the patient has co-exis- tent corneal disease, surgeons would be best served by managing the corneal aspect before cataract sur- gery. "Be very careful with long and short eyes," Dr. Koch said. "Use the Holladay II formula if you've got very short eyes—the ratio of anterior chamber depth to the axial length can impact the accuracy of the IOL selection." In long eyes, surgeons can use the Wang-Koch formula to make adjustments to the axial length and recalculate formulas to use a slightly lower power. "It will help eliminate post-op hyperopia," he said. Dr. Koch advised using this formula for eyes over 25 mm. Be prepared Warning patients up front that out- comes could be less than stellar is highly recommended, Dr. Koch said, but also alert patients that there are options to correct the surprises, but those options may include out-of- pocket expenses. "If possible, let patients know about all the possibilities, how you might treat them, and how much it's gong to cost," he said. "That way there are no surprises, and patients are eternally grateful if nothing goes wrong." Without this pre-op discussion, patients can become very upset post- op when they learn that additional procedures are required to get their vision to the point they expected prior to cataract surgery, Dr. Trattler said. Treatments can range from put- ting the patient back in spectacles or contact lenses to performing LASIK or surface ablation to implanting a AT A GLANCE • While IOL calculations are accurate, some patients will end up off-target • Identify and treat patients with ocular surface issues before scheduling cataract surgery • Consider getting an OCT on patients with questionable macula • When surprises do occur, treatment can be either lens- or cornea-based piggyback IOL or performing an IOL exchange, Dr. Talley Rostov said. "We're getting better with our formulas, so we're getting better with reducing the number of surprises," she said. Dr. Koch's team recently demonstrated the importance of taking into account posterior corneal astigmatism, so "we have completely changed our nomograms for toric IOLs," Dr. Koch said. (See his nomograms in Figure 1.) Be proactive Should the patient end up off-target, "don't panic," Dr. Talley Rostov said. "I don't get stressed out about it— almost all post-refractive surgery patients are at risk, so it's not a true surprise if it does happen." In her hands, Dr. Talley Rostov says more than a diopter off-target will result in a lens exchange, and she usually performs these within 6-8 weeks of the original surgery. "That's when the lens will still come out easily," she said. continued on page 62 The Baylor toric IOL nomogram takes into account posterior corneal astigmatism, using the Holladay II and surgeon-induced astigmatism. Here, both with-the-rule astigmatism and against-the-rule astigmatism nomograms Source: Douglas D. Koch, M.D.