EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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February 2012 IOLs February 2011 EW FEATURE 61 the residual astigmatism issues, he said. Dr. Holladay said the formula is simple—post-op Ks minus pre-op Ks will give you the SIA, and adding the SIA to the pre-op Ks will give you the post-op Ks on the next case. "Toric IOLs should always be aligned with the steepest meridian of the cornea post-op," he said. "You're trying to predict where that is by adding the SIA to the pre-op astigmatism." SIA for right eyes will differ from left eyes, "and that has to do with the incision architecture," Dr. Hill said. "Thinking the number should be the same for all patients is a misconception." Dr. Hill recently introduced a new tool that may help surgeons cal- culate SIA, www.SIA-calculator.com, a "completely HIPAA-compliant" calculator with all data stored "in the cloud." Conservatively, most surgeons need about 60 cases to determine their SIA, Dr. Hill said, although Dr. Koch and Li Wang, M.D., assistant professor of ophthalmology, Cullen Eye Institute, BCM, believe surgeons who are consistent with incisional technique and placement may be able to use as few as 20 cases. They've published a study look- ing at post-op cataract incisions via optical coherence tomography to de- termine the effect on wound heal- ing,1 and "a small Descemet's detachment was present in 37% of eyes at 1 day post-operatively, de- creased to 4% at 1 to 3 months, and was absent after 3 months," Dr. Wang said. Dr. Kezirian noted SIA "is not stable until at least 3—and probably not until 6—months after surgery. "To really assess what has been induced by the procedure, you have to analyze longer-term data than most cataract surgeons collect," he said. Dr. Brass said wounds may "re- model over some time," and agreed that may affect SIA amounts. Dr. Hill, however, said wounds will start to stabilize between 4 and 6 weeks, depending on how much stretching was involved. Minimizing your SIA Operating on axis "will always di- minish the astigmatism," Dr. Brass said, but operating 90 degrees away Whether you're just beginning or experienced in cataract and refractive surgery, ASCRS is the professional society that's right for every stage of your career. Established Anterior Segment Ophthalmologists Mid-career is perhaps the most challenging period for today's ophthalmologist. The clinical and technological changes have never come faster and the regulatory concerns have never been greater. ASCRS' Annual Sympo- sium and Winter Update offer the education and networking needed to help your practice excel, and our ASCRS MediaCenter provides targeted online content addressing the issues most pressing to you. ASCRS' monthly Journal of Cataract and Refractive Surgery reports on all aspects of anterior segment surgery, and our meetings are focused, well-organized, and highly interactive. eyeCONNECT, ASCRS' online clinical service, lets you share questions and answers with like-minded peers in a private and supportive environment. ASCRS' commitment to fostering excellence through collaborative exchange is unmatched by any other ophthalmic organization. Join ASCRS today! The Society for Surgeons AMERICAN SOCIETY OF CATARACT AND REFRACTIVE SURGERY 4000 Legato Road, Suite 700, Fairfax, VA 22033 • 703-591-2220 • www.ASCRS.org will adversely affect the amount of corneal astigmatism. "If you flatten in one meridian, you will steepen in the other." Dr. Brass typically works at 10 degrees for the left eye and 190 for the right. "The debate becomes operating on the step axis vs. staying where I am most comfortable," he said. By using the toric calculator and choos- ing a lens with greater astigmatism correction, he is able to compensate continued on page 63 An ASCRS Membership For every stage of your career