EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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EW FEATURE 38 Management of the irregular cornea • January 2016 AT A GLANCE • Those getting used to topographic machinery may first want to become versed in taking scans. • Unlike wavefront, which uses one image, the topo-guided approach uses a compilation of images. • For those just beginning, choosing cases wisely is advised. by Maxine Lipner EyeWorld Senior Contributing Writer of clinical ophthalmology, Washing- ton University School of Medicine, St. Louis, are now beginning to put such new technology to use. As a full-time refractive surgeon, Dr. Wexler views topography-guided ablations with his new WaveLight Allegretto Wave Eye-Q Excimer Laser (Alcon, Fort Worth, Texas) as something that is going to make a difference in his practice. "The FDA study was a normal eye study wherein they looked at myopia and astigmatism and had incredibly good results," Dr. Wexler said. Raymond Stein, MD, medical director, Bochner Eye Institute, Toronto, and associate professor, University of Toronto, has been us- ing the topography-guided technol- ogy for some time now and sees it as a step forward. "I think it's a signif- icant advance in refractive surgery when dealing with patients with irregular astigmatism, especially keratoconus patients," Dr. Stein said. "We have been using topography- guided PRK and crosslinking for 5–6 years, and it's an opportunity to im- prove best corrected spectacle acuity by decreasing irregular astigmatism." It can also help treatment of hyper- opia where a patient's visual axis is usually not centered on the pupil, he said, explaining that topo-guided PRK or LASIK ablations can be cen- tered over the line of sight, which can improve the quality of vision. In addition, topography-guided ablation can be used to manage prior refractive surgery complica- tions such as a small optical zone or glare and halos, Dr. Stein said, but stressed that such treatments are not for those just beginning with the technology. Beginning use Dr. Wexler noted that while he has not yet begun using the laser himself, his technicians have been trained by the company in taking WaveLight Topolyzer (Alcon) scans. "It seems fairly easy and very similar to other instruments we use to ac- quire images," Dr. Wexler said. The idea is to get the technicians used to taking the scans, but there are no plans to use the laser itself before early 2016, he explained. "Whenever we introduce new technology in our practice, we approach it cautiously," Dr. Wexler said. In addition to focusing on training technicians, the practice is honing in on outcomes using Zubisoft IBRA software (Oberhas- li, Switzerland). "We introduced wavefront-guided technology to our WaveLight system about 5 months ago, and I looked at our 3-month outcomes and saw we're getting better outcomes than with wave- front-optimized," Dr. Wexler said in an October 2015 interview. "I an- ticipate doing the same thing when we get topo-guided, where we'll pick our first 10 cases—routine, easy Getting the lay of topographic ablation landscapes A look at how physicians can effectively use this innovative machinery M ore and more practi- tioners in the U.S. have equipment capable of topographic ablation waiting in the wings or already in use. Practitioners such as Stephen A. Wexler, MD, professor take more than one person to take the picture in those instances where patients can't open their eye wide enough," he said. "If the lashes are in the way, we have used an eye lash curler to get them out of the way." "The ocular surface must be optimized by medical therapy in advance of the treatment day, as a good topography scan is reliant on a healthy tear film," Dr. Barsam said. The WaveLight laser (Alcon) analyzes the Pentacam (Oculus, Arlington, Wash.) images and grades them according to quality; he then reviews them all before treating to ensure that they correspond and are of good quality. Optimizing the ocular surface The very first thing to consider in optimizing the ocular surface is the tear film. "Roughly one-third of my patients will come in with the diagnosis of dry eye or ocular surface disease," Dr. Stonecipher said. "If needed, I will place these individuals on cyclosporine and discontinue their contact lens wear until the surface is normalized." In some cases, he will use punctal occlusion after treating inflammation, and if meibomian gland disease becomes a problem, an antibiotic of corticosteroid may become necessary. "Finally, with newer diagnostics, we are seeing sig- nificant meibomian gland dropout even in younger patients," he said. "If severe, I have recommended LipiFlow [TearScience, Morrisville, N.C.] treatments prior to surgery." Dr. Barsam will pretreat any meibomian gland dysfunction with a combination of nutritional supple- ments, hot compresses, or LipiFlow and a topical anti-inflammatory, such as cyclosporine. Be sure to treat issues like bleph- aritis and dry eye ahead of time in order to allow good readings, Dr. Durrie said. You also need to be fairly quick, he said, and not have the patient staring at the screen for a long time before taking the reading because this could dry out the eyes. When not to use a topographic ablation "We can't look at this technology as a way to treat all of our previous refractive surprises and unhappy patients," Dr. Stonecipher said. "We need to learn from out colleagues that this technology can create prob- lems in this patient population, and they may be permanent problems." He recommended not treating pa- tient with active dry eye disease. "We are currently learning from several great clinical trials where this technology can be coupled with crosslinking to help this subset of patients," he said. "Patients with active systemic disease (i.e., collagen vascular, autoimmune, or immu- nodeficiency diseases) or ocular disease (i.e., advanced glaucoma or uncontrolled diabetes) should not be considered." It's also import- ant to follow the "golden rules" of refractive surgery, Dr. Stonecipher said, to ensure that patients are good candidates. At this time, Dr. Durrie would not use topographic ablation for patients who have had previous sur- gery or those who have already thin corneas. He said that it's important to realize that you could really get into trouble if using this technol- ogy in a patient in whom it's not currently indicated. "Move slow and easy with it," he said. Topographic ablation for a patient with an irregular cornea One option that has been used for patients with an irregular cornea, outside of the U.S., is topography- guided surface ablation and corneal crosslinking, Dr. Durrie said. Look- ing toward the spring, hopefully we will have both topography-guided ablation and crosslinking approved, he said. "I think there will be a lot of interest in that." But currently this treatment is off-label. If the patient is intolerant of contact lenses and suffers from poor quality of vision, Dr. Barsam will use topographic ablation as an option for patients with irregular corneas. "As I combine these treatments with crosslinking, they need to have a total corneal thickness of more than 425 microns to allow room for the ablation and epithelial removal be- fore safe crosslinking," he said. EW Editors' note: Drs. Stonecipher and Durrie were clinical investigators on the U.S. topographic ablation clinical study. Drs. Barsam and Stonecipher have financial interests with Alcon. Contact information Barsam: abarsam@hotmail.com Durrie: ddurrie@durrievision.com Stonecipher: stonenc@aol.com Tips continued from page 37