Eyeworld

MAY 2012

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

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60 EW MEETING REPORTER May 2012 The latest on femto Reporting live from APAO/SOE Busan 2012, Busan, Korea Femtosecond lasers were once again the hot topic at an early afternoon session in which surgeons discussed how they use the lasers in refractive surgery. Eui-Sang Chung, M.D., Seoul, South Korea, used the VisuMax Laser (Carl Zeiss Meditec, Jena, Germany) to perform small incision lenticule extraction (SMILE) during refractive lenticule exchange (ReLEx) and said he uses a 3-5 mm midperiphery linear incision to remove the lenticule instead of creating a flap. "It's a very simple procedure," Dr. Chung said, adding that there are disadvantages to making side cuts, which are avoided in these procedures. "Seventy-five percent of the weakening in corneal biomechanics in refractive surgery comes from the side cut, not from the cuts to the lamellar bed," he said. "Although there is still some weakening of the cornea, it is dramatically less when a small diameter, no side cut, thin lamellar cut is created in ReLEx SMILE." The small diameter cut is less than 7 mm. Michael Lawless, M.D., Sydney, Australia, presented his 1-year results with the LenSx Laser (Alcon, Fort Worth, Texas). Dr. Lawless analyzed his fem- tosecond data (n=412), asking, "How do we rate for safety, accuracy, and profitability?" His data was part of a larger clinical evaluation that included 1,447 cases at the first four centers using the LenSx. In that evaluation, 92% of cases could be completed. Despite tweaking the technique as surgeons become more familiar with it, Dr. Lawless said the data is showing that accuracy results with the femtosecond laser are "excel- lent." Astigmatism results also are "clearly better," he said. His current technique includes a Editors' note: This Meeting Reporter contains original reporting by the EyeWorld news team from APAO/SOE Busan 2012, Busan, Korea 4.9 mm diameter capsulotomy, with an energy setting of 15 uj and a spot laser setting of 4:3. Fragmentation is done at 5.2 mm on axis with an an- terior offset of 500 µm and posterior offset of 1,100 µm. The primary in- cision is a three-plane reversal trape- zoidal configuration, and Dr. Lawless noted that he uses minimal OVD and titrates the hydrodissec- tion during surgery. Although the most current data shows an incidence of capsular rup- ture to be between .79% and 4.9% using manual techniques before the laser refractive cataract surgery was available, Dr. Lawless said he hasn't had any such tears in his 412 cases. Other problems consisted of suction breaks during the procedure (3), pupillary constriction after laser surgery (6), and anterior capsular tags (5). "My capsular tear rate is lower than I can achieve with manual surgery, so it can be that way for any surgeon," Dr. Lawless said. Editors' note: Dr. Chung has no finan- cial interests related to his comments. Dr. Lawless has financial interests with Alcon. Trading spurs Among the things newer imaging technologies provide are new param- eters for assessing the angle in glaucoma. For instance, Hon Tym Wong, M.D., Singapore, and colleagues looked into using the Schwalbe's line instead of the scleral spur—the typical landmark for assessing the angle using UBM and AS-OCT, he said during a glaucoma symposium. Particularly when using high definition OCT (HD-OCT), Dr. Wong found that Schwalbe's line (the line produced on an HD-OCT image by Descemet's membrane, the outer limit of the corneal endothelial layer) was more consistently identifiable in images than the scleral spur and con- tinues to be visible, serving as a land- mark even in advanced disease. Pending more data, he said, Schwalbe's line may be a more robust parameter for assessing the angle closure. Editors' note: Dr. Wong has financial interests with Carl Zeiss Meditec. Novel parameters Aung Tin, M.D., Singapore, and col- leagues undertook a study specifi- cally aiming to find and assess novel risk factors for angle closure. Cornea-based presbyopia correction The q-value measures the shape of the cornea. The ideal asphericity, according to Arthur Cheng, M.D., Hong Kong, is about –0.46, describ- ing a more prolate cornea. In the early days of LASIK, he said, surgeons used to target positive q, but this put the point of focus anterior to the retina. Dr. Cheng spoke at a refractive symposium on cornea-based presby- opia correction. It is the ideal time for laser re- fractive presbyopia correction, said Hungwon Tchah, M.D., Seoul, South Korea. There is a large market owing to the aging population; favorable economics in terms of a more financially capable target pop- ulation; and a growing demand aug- mented by technological advances such as smartphones and tablet PCs. Reporting moderate, less-than- perfect results from using the SUPRACOR excimer laser presby- opia-correction procedure (Bausch + Lomb, Rochester, N.Y./Technolas Perfect Vision, Munich, Germany) in his patients, Dr. Tchah concluded that it is an effective, if "evolving," procedure. Halo and glare were sometimes a problem for his pa- tients, but generally resolved after 6 Traditional risk factors include shallow anterior chamber depth, axial length, pupil size, and demo- graphic information such as age and gender, he said. To this list, he and his colleagues added iris parameters (curvature, thickness, area); anterior chamber width, area, and volume; lens vault; dynamic changes in iris volume; and vitreous conduction. They found anterior chamber volume, anterior chamber area, and lens vault to be the three best single predictors, and the optimum model for assessing risk includes six param- eters: anterior chamber volume, anterior chamber width, anterior chamber area, iris thickness, lens vault, and iris area. Dr. Tin and colleagues published their findings in last month's issue of Ophthalmology. Editors' note: Dr. Tin has financial interests with Carl Zeiss Meditec.

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