Eyeworld

EW FEATURE 63 Expectations, IOL calculations, are two problem areas I t's a growing patient demo- graphic—patients with previ- ous refractive surgery who now come to your office for cataract surgery. "We often see patients who had LASIK or PRK 10 years ago when they were in their early 50s. Now they're in their early 60s and they think they need an enhancement," said William Wiley, M.D., Brecksville, Ohio. "It's not the LASIK that's changed, it's that they need cataract surgery." Managing these patients can be more challenging than other patient groups. First, these patients tend to have higher expectations, said Li Wang, M.D., research associate, Department of Ophthalmology, Baylor College of Medicine. "I think the key is managing pa- tients' expectations," said Harry H. Huang, M.D., Bethesda, Md. He goes out of his way to emphasize that cataract post-op vision will not be as perfect as it may have been after the patient's initial refractive surgery. He will also tell patients that some surgeons believe there is a 20% chance that they will need a lens exchange—although his per- sonal experience with lens exchange is not that high, he wants the pa- tient to understand what might occur post-op. He will refer difficult anatomical cases to a like-minded local colleague for a second opinion. If he senses a patient has a more dif- ficult personality, he will often delay surgery or not perform it at all. Surprisingly, although this pa- tient group generally has high hopes, a number of post-RK patients have suffered through poor vision and are often happy with the results that cataract surgery can give, said Douglas D. Koch, M.D., professor of ophthalmology, the Allen, Mosbacher, and Law Chair of Ophthalmology, Houston. These patients may not always think to mention their previous re- fractive surgery early in the pre-op process, said Mark H. Blecher, M.D., Philadelphia. "I do a lot of combination cases with our retina department," he said. "Occasionally, I do the surgery but don't get to talk to the patient much before. Then the patient will tell me in passing that he or she had LASIK. That can throw a monkey wrench into things." This is why it's crucial that staff members and pre-op forms ask about previous refractive surgery, Dr. Blecher said. While surgeons commonly try to track down pre-op refraction data, this can be hard to obtain if the pa- tient had surgery outside of the U.S. or if the doctor has retired. Other times, the challenge comes in track- ing down when the patient had sur- gery and what procedure was performed. "With earlier generation PRK, the optical zones were smaller, and those patients have flatter true keratometry and a greater chance of refractive surprise. That's not a large volume of patients, but it does crop up," Dr. Blecher said. IOL calculations Another major challenge in treating patients who have had previous re- fractive surgery is using an appropri- ate IOL calculation. Although there are numerous formulas available to calculate appropriate IOL power, one tool surgeons said they commonly use is the ASCRS post-refractive sur- gery IOL calculator (http://iol.ascrs. org/). "We enter all data available into the calculator," said Dr. Wang, who is involved in the design of the cal- culator. "In the output section, we pay more attention to results derived from formulas relying on part of the historical data (change in manifest refraction induced by LASIK/PRK) and current measurements (methods in the middle column) and methods requiring no prior data at all (meth- ods in the right-hand column)." "I think in general the ASCRS calculator is good—it gives a median option and a higher and lower one," Dr. Wiley said. "I use it with all my patients if I have the previous refrac- tive history." When Dr. Wiley does not have previous refractive information, he uses the WaveTec (Aliso Viejo, Calif.) ORange aberrometer to fine-tune the best IOL choice. The ORange lets surgeons take intra-operative refrac- tive measurements. Dr. Huang commonly uses the IOL calculation formulas available on the website of Warren Hill, M.D., Mesa, Ariz. (www.doctor- hill.com). When working with IOL calcu- lation formulas in these patients, the double K version must be used, Dr. Wang said. "The best way to do this is to use the Holladay Consultant Program [Bellaire, Texas]," Dr. Wang said. "One should select the button February 2011 September 2011 Challenging cataract cases by Vanessa Caceres EyeWorld Contributing Editor Refractive patients pose challenges during cataract surgery ASCRS post-refractive surgery IOL calculator. IOL powers are calculated for three categories of methods and displayed in three columns AT A GLANCE • Cataract patients who have previ- ously had refractive surgery often have higher expectations for surgi- cal outcomes • A number of IOL calculation tools, including the ASCRS post-refractive surgery IOL calculator, can help surgeons pinpoint the best IOL for patients. Newer devices like the ORange aberrometer allow surgeons to take intra-operative refractive measurements • Patients with previous RK present even more of a challenge to cataract surgeons because of factors such as hyperopic drift • Managing expectations before surgery can help keep patients prepared for the occasional refractive surprise continued on page 64

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