Eyeworld

83 November 2016 EW MEETING REPORTER Refractive surgery goes back to basics A symposium introduced residents— and others wanting to brush up—to corneal and lens-based refractive surgery. The session included an exten- sive overview of diagnostic testing, patient screening, and how this information should be analyzed to determine candidacy for different types of refractive surgery. Speakers also highlighted procedural steps and complication management. When it comes to a corneal refractive procedure, which do you choose—PRK or LASIK? Marguerite McDonald, MD, Lynbrook, New York, said PRK is best suited for pa- tients with slightly thin yet normal corneas, patients with dry eyes, those at risk for displaced flap due to activities, and monofocal or multifocal IOL touchup patients. The risk of ectasia is still a concern for both procedures, but based on published research, there is a higher incidence rate for ectasia post-LASIK compared to post-PRK. As such, Dr. McDonald said we can infer there is less ectasia risk when performing PRK on thin corneas. However, physicians should not infer that PRK is always safe on thin corneas. "If you wouldn't do LASIK on this case, then you shouldn't do PRK," Dr. McDonald said. Bonnie Henderson, MD, Bos- ton, described the options for lens- based refractive surgery for cataract patients. "There isn't one perfect lens for every patient," Dr. Henderson said, explaining that it's important to know the different types of lenses, conduct extensive preop testing, and understand the patient's lifestyle and refractive goals. If the eye overall is healthy— determined by a thorough preop exam—and the patient desires spectacle independence, a toric, multifocal, or accommodative IOL or monovision might be an option, depending on the patient's individ- ual situation. Even if determined a good candidate for a refractive IOL, the patient should still be counseled Richard Lindstrom, MD, Minne- apolis, discussed the CAPSULaser (CAPSULaser, Los Gatos, California), a new device that creates a precisely sized capsulorhexis with no tissue bridges. The device is currently available in Europe but not the U.S. David Chang, MD, Los Altos, Cali- fornia, presented information on the ZEPTO capsulotomy device (Myno- sys, Fremont, California). Symposium presenters discussed newer types of IOLs, including the now Food and Drug Administra- tion-approved Symfony intraocular lens (Abbott Medical Optics) as well as pros and cons of trifocal IOLs and newer multifocal IOL technol- ogy, including the ReSTOR +2.5 D (Alcon), the PRECIZON presbyopic IOL (Ophthec, Netherlands), and the Perfect Lens, which allows for in vivo modifications of the IOL. The latter would bring a paradigm shift within cataract surgery and could one day eliminate the need for IOL exchange and laser vision correction enhancements, said George Waring IV, MD, Charleston, South Carolina. Within the IOL realm, ophthalmolo- gists appear to be shifting their focus on to better intermediate vision as well as good quality functional vision, said Abhay Vasavada, MD, Ahmedabad, India. Warren Hill, MD, Mesa, Ari- zona, updated attendees on the use of pattern recognition, radial basis function, and artificial intelligence to determine IOL power selection, a concept that he shared at last year's AAO meeting. "You may think this is geeky technology, but it's all around you," said Dr. Hill, noting that this same approach is used for facial recognition and fingerprint identification. Within a 17-week period this year, there were 35,780 IOL calculations made with Dr. Hill's website, RBFcalculator.com. The calculator is available for free on the website and via the ASCRS website. It is also incorporated in the Haag-Streit LENSTAR biometer (Koniz, Switzerland). Editors' note: The physicians have financial interests with the companies they presented on. screening for hydroxychloroquine retinopathy, said Sarah Wellik, MD, Miami, during "Spotlight on Ophthalmic Manifestations of Sys- temic Diseases: What You Need to Know." The AAO update published earlier this year recommends annual screening once a patient has used hydroxychloroquine for 5 years and notes that spectral domain optical coherence tomography can iden- tify signs of toxicity more quickly than a visual field test, Dr. Wellik said. Hydroxychloroquine is used in some patients with rheumatological disease. Dr. Wellik discussed other drugs that can have ocular toxicity in certain patients, such as erectile dys- function (ED) medication. This drug type can cause anterior ischemic optic neuropathy in certain patients, especially older men—which is also the population most likely to use ED drugs. Dr. Wellik's take-home message was: If a patient presents with new ocular manifestations, ask about any new medications. In another presentation at the same session, Raquel Goldhardt, MD, Miami, addressed systemic infections with ocular effects. Have a high suspicion of ocular syphilis in patients experiencing eye pain, red- ness, and interstitial keratitis. This is because there were 20,000 new cases of primary or secondary syphilis diagnosed in the U.S. in 2014, a 40% increase compared with 2010. Other infections to consider in certain patients include infective endocardi- tis—more common in patients with dental extractions or a resection of the prostate—and endogenous endophthalmitis. Risk factors for the latter include patients with a recent hospitalization, urinary tract infection, intravenous drug abuse, or immunosuppression. Editors' note: Drs. Wellik and Goldhardt have no financial interests related to their comments. Looking to the future of cataract technology and innovations "Cataract Surgery: The Cutting Edge," moderated by Robert Osher, MD, Cincinnati, covered innova- tions within the cataract realm. "Hiding in Plain Sight: The Enigmat- ic Cornea and IOL Calculations." Dr. Koch shared seven different cases to detail different issues in measuring the cornea for IOL calcu- lations. He first described a "perfect" case and questioned why all cases don't turn out like this. "When we do our calculations, we measure a lot of parameters of the eye," he said. Anterior corneal curvature, axial length, lens thickness, and anterior chamber depth all need to be accounted for. The goal of most IOL calcu- lation formulas is to predict the effective lens position, Dr. Koch said. Once you know that, you can pretty much figure everything else out, he said. So, how well do physicians do? Dr. Koch said results are "not as great as we think." About 70% to 80% are accurate within plus or minus 0.5 D of the predicted. Dr. Koch also discussed mea- suring the anterior cornea and encouraged physicians to "critically evaluate raw data." There are many reasons for variability and inaccu- racy, he said, including tear film, corneal pathology, user skills, and zones that are measured. The role of the posterior cornea is also important to factor in, and Dr. Koch suggested extrapolating the posterior corneal curvature after measuring the anterior cornea. To- mography, OCT, and other technol- ogies may be helpful with this. The small difference in refrac- tive index between the posterior cornea and aqueous makes the posterior cornea hard to measure, he said. This makes it a tough surface to identify and quantify. Editors' note: Dr. Koch has financial interests with Abbott Medical Optics (Abbott Park, Illinois), Alcon, Clar- ity (Pleasanton, California), Perfect Lens (Irvine, California), iOptics (The Hague, Netherlands), and Ziemer (Port, Switzerland). Hydroxychloroquine retinopathy guidelines call attention to medications with ocular effects Ophthalmologists should be aware of recently published and revised guidelines from AAO regarding continued on page 84

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