OCT 2012

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

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Page 34 of 168

32 32 EW REFRACTIVE SURGERY October 2012 Assessing femto-assisted astigmatism Refractive editor's corner of the world by Vanessa Caceres EyeWorld Contributing Writer Users praise advantages, cite need for better nomograms A stigmatism continues to take center stage for today's refractive cataract surgeon. Based on the data of Warren Hill, M.D., approximately 50% of today's cataract patients have at least 0.75 diopters of astigmatism. Clearly astigmatism must be dealt with if patients are going to achieve their best uncorrected vision following surgery. While toric lenses have become the mainstay for larger degrees of astigmatism, limbal relaxing incisions (LRIs) are commonly used for astigmatism in the setting of presby- opia-correcting IOLs as well as for treating lower amounts of astigmatism. While effective, LRIs can be unpredictable due to the nature of the procedure. Femtosecond lasers have the potential to improve the precision and perhaps accu- racy for the treatment of corneal astigmatism. We are honored to learn from the experiences of Drs. Culbertson, Foster, Packer, and Talamo with several of the femtosecond technologies in this month's "Refractive corner of the world." Kerry Solomon, M.D., refractive editor P redictability and control: Those are two words you commonly hear when you ask surgeons about the advantages of using femtosecond lasers for astigmatism treatment. These same surgeons acknowledge that this is still an evolving technology that needs long-term results and better nomo- grams to assist during procedures. "In general, the femtosecond laser has the potential to make incisions precisely in the position, depth, and angulation that is desir- able. It's extremely predictable in terms of the depth of the incision and in the optic zone," said William W. Culbertson, M.D., professor of ophthalmology, and director, Cornea and Refractive Surgery Serv- ices, Bascom Palmer Eye Institute, Miller School of Medicine, Univer- sity of Miami. "You can do this with more precision than you can with a blade." With a blade, the depth created is not as uniform as it will be when created by a laser, Dr. Culbertson added. EyeWorld spoke with surgeons experienced with the OptiMedica (Sunnyvale, Calif.), LensAR (Winter Park, Fla.), and LenSx (Alcon, Fort Worth, Texas) lasers to hear their thoughts on their respective models for use in astigmatic cataract pa- tients. OptiMedica experience OptiMedica's Catalys laser system has been in the news recently with the U.S. FDA's approval of its corneal incisions. Jonathan H. Talamo, M.D., associate clinical professor of ophthalmology, Harvard Medical School, Boston, has worked with the company for 5 years to assist in the laser's design and has 3 years of ex- perience with the OptiMedica laser, performing procedures in the Do- minican Republic. He anticipates ob- taining a model soon for treatment. "When we proceed with the laser, the cuts we do should have finely positioned diameter, length, depth, and centration," he said. "The laser allows more reproducibil- ity, and when you combine it with Wavefront-guided refraction during cataract and refractive lens exchange surgery Source: Mark Packer, M.D. optical coherence tomography, you can tell the laser how deep to go in every spot." That standardization of astig- matic incisions was also something discussed by Dr. Culbertson. Dr. Culbertson has 3 years of experience with the OptiMedica laser, perform- ing procedures in the Dominican Republic. With the laser, surgeons can use the bevel direction to help stabilize the effect of the incisions—some- thing that you cannot standardize manually, Dr. Culbertson said. "You can make these titratable—you can make the incision but not open it all the way to the bottom so the resid- ual adhesions can remain intact at a certain position and depth. For ex- ample, you can treat 3 diopters and make the incision, but it forms a path of least resistance so the inci- sion doesn't spread open immedi- ately. It's still attached so you can go back later and deepen it to get a greater effect. That's something you can't do with a blade." Drs. Culbertson and Talamo believe nomograms tailored to the femto technology will make astig- matic incisions even more effective. "The establishment of nomograms will be a bit difficult, but it can be done. We just need to get a large enough number of patients to use it," Dr. Culbertson said. LensAR experience LensAR's 510(k) submission for corneal incisions is currently being reviewed by the. FDA for its corneal incisions this year, said Mark Packer, M.D., clinical associate pro- fessor of ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland. Dr. Packer and other surgeons have used the laser abroad, including having recent experiences in Latin America. Dr. Packer expects the use of the laser for astigmatism treatment will offer some benefits. "The drive toward greater accuracy and pre- dictability in the outcomes of our incisional surgery for astigmatism represents a tremendous benefit for our patients, who will be able to get the desired results with a single pro- cedure," Dr. Packer said. "Ultimately, our abilities to titrate and enhance precise limbal relaxing incisions [LRIs] may prove superior to out- comes achieved with toric IOLs for most degrees of correction." He described fundamental ways in which LRIs created with femtosec- ond lasers are different than blade- based LRIs. First, the laser should make placement of the incisions easier. "Successfully placed LRIs reduce the patient's cylinder without an over- correction or axis shift. Determining the exact location of the cylinder is often challenging," he said. Femtosecond technology seems to indicate a more precise manner for incisional correction of astigmatism, including high degrees of astigma- tism in post-keratoplasty eyes, Dr. Packer said. "Common sense suggests that automating the incisional technol- ogy and thus eliminating the vari-

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