Eyeworld Daily News

EW SHOW DAILY 40 Meeting Reporter Tuesday, April 21, 2015 by Chiles Aedam R. Samaniego EyeWorld Asia-Pacific Senior Staff Writer W ith astigmatism, said John Berdahl, MD, Sioux Fall, S.D., it's easy to get to the 5-yard line, but hard to get into the end zone. Despite the challenge, Dr. Berdahl said surgeons "have to be diligent in trying to correct astigmatism. Dr. Berdahl discussed "The Im- pact of Rotational Error in Toric IOL Patients: Goals, Surgically Induced Astigmatism, and the Posterior Cor- nea" as part of the EyeWorld CME Educational Symposium on "Driving Adoption and Outcomes with Toric IOLs: Pre-, Intra-, and Postoperative Pearls for Success." The symposium, according to program chair John Vukich, MD, Madison, Wis., was developed based on "education gaps and needs" as revealed by the 2014 ASCRS Clinical Survey. In the survey, he said, 11.5% of respondents said they used manual keratometry and automated Ks as the primary preoperative measure- ment that drives their astigmatism axis decisions when implanting IOLs; 6% used anatomical land- marks and 31% ink marking at the slit lamp with no additional instru- ments to align the preoperative axis with the intraoperative axis when placing toric IOLs during surgery; less than half reported calculating surgically induced astigmatism (SIA); 25% ignored posterior corne- al cylinder because "it is typically insignificant"; and 30.2% believed 10 degrees or more of postoperative rotational error is acceptable before visual quality and visual acuity are significantly affected. Driving outcomes for successful toric IOL implantation Dr. Berdahl says surgeons need to be diligent in correcting astigmatism. Dr. Berdahl attributed residual astigmatism after toric IOL implan- tation in any given case to at least one of 3 causes: "wrong location," or misalignment, due to poor measure- ments, poor calculations, surprising SIA, posterior Ks, IOL rotation, or poor IOL placement; "wrong lens," due to poor measurements, poor calculations, surprising SIA, or poste- rior Ks; and "wrong eye," by which he meant an eye with ocular surface disease, anterior basement mem- brane corneal dystrophy (ABMD), or irregular astigmatism. If the residual astigmatism is due to the wrong location, the IOL will have to be rotated; if due to wrong lens, then a lens exchange or laser vision correction may be considered. In the case of wrong eye, he said, no refractive error can be adequately corrected until the disease is treated. To illustrate the significance of SIAs in IOL alignment and wrong lens decisions, Dr. Berdahl said that with his own SIAs, with a standard deviation of about 0.6 or about 30%, he could be inducing a difference of up to 0.8 D. Meanwhile, research done by authors such as fellow symposium faculty member Douglas D. Koch, MD, Houston, showed the contribu- tion of posterior corneal astigmatism to total corneal astigmatism. Planning should therefore cer- tainly take the posterior cornea into consideration. In this regard, David R. Hardten, MD, Minneapolis, suggested using the Barrett Toric IOL Calculator available at www.ascrs. org/barrett-toric-calculator. Aside from this point, Dr. Hardten said that planning for use of toric IOLs should include almost every patient, and it should be discussed preop whether spectacles for astigmatism would bother the patient—even low amounts degrade vision. The surgeon must also decide whether astigmatism is mostly regular or significantly irregular. The axis should be verified using not just keratometry but topography and tomography. Dr. Hardten added that high expectations of patients will require occasional enhancements. In terms of assessing alignment preoperatively and intraoperative- ly, Bonnie An Henderson, MD, Boston, discussed manual marking and "high tech" options as provided by various new devices currently available. She said there are many helpful tools now available, both manual and automated, that sur- geons should use as they improve outcomes. Concluding the session, Dr. Koch said that astigmatism correc- tion is a process, and that surgeons must follow critical steps before, during, and after surgery. He said that it is "mandatory" for all sur- geons, in all cases, to be prepared to perform adjustments postopera- tively. EW Editors' note: This event was supported by unrestricted educational grants from Abbott Medical Optics (Abbott Park, Ill.), Alcon (Fort Worth, Texas), and Bausch + Lomb (Bridgewater, N.J.). Congratulations to Dr. Stahl, yesterday's winner of the new iPhone 6.

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