EyeWorld Asia-Pacific June 2013 Issue

June 2013 14 EWAP FEAturE The Toric Results Analyzer at www.astigmatismfix.com was developed to deter- mine if a previously placed toric IOL is properly aligned. Managing postop refractive errors with premium IOLs Pearls to avoid (and better handle) post-surgery surprises T here’s little room for forgiveness when you implant premium IOLs. “Patient expectations are higher any time a patient pays an out-of-pocket cost,” said Terry Kim, MD , professor of ophthalmology, Duke University School of Medicine, Duke University Eye Center, Durham, NC, USA. That said, unexpected refractive errors are bound to occur sometimes even for the most careful surgeons. Here’s a review of some of the most common errors that anterior segment surgeons face with toric, accommodating, and multifocal IOLs and how to manage them—or how to avoid the problems altogether. Toric IOLs Because expectations are higher in premium IOL patients, Dr. Kim relies on accurate keratometry and biometry measurements during the preop assessment to try to avoid postop by Vanessa Caceres EyeWorld Contributing Writer surprises. Preventive moves have led him and his practice to keep the rate of postop errors low, he said. “We get a corneal topography on these patients and also make sure the keratometry reading is reliable,” he said. He said devices such as the Lenstar LS900 (Haag- Streit, Mason, Ohio, USA) and IOLMaster 500 (Carl Zeiss Meditec, Dublin, Calif., USA) that assist with biometry and keratometry are more accurate than they have been in the past. Surgeons should use a third- or fourth-generation IOL formula for biometry to help avoid refractive surprises as well, Dr. Kim said. In addition to the Holladay 2 formula, Dr. Kim recommends the Haigis or SRK-T formulas for axial lengths of greater than 25 mm; if the patient has an axial length of less than 22 mm, he prefers the Hoffer Q formula. Dr. Kim also makes sure that ocular surface irregularities— including dry eyes, blepharitis, anterior basement membrane dystrophy, and Salzmann nodules—are addressed prior to surgery, so they do not throw off the keratometry readings, which directly affect toric IOL calculations. “These conditions increase your chances of refractive surprises,” he said. Residual astigmatism is the number one error faced by John Berdahl, MD , Sioux Falls, SD, USA, when implanting toric IOLs. The first step he suggests is to find the cause of the astigmatism—it could be inaccurate keratometry, surgically induced astigmatism, the IOL is not in the ideal axis, there could be problems with the posterior corneal curvature, or the patient may have ocular surface disease, Dr. Berdahl said. Dr. Berdahl finds the most common cause of postop toric errors in his hands is underestimating the posterior corneal curvature. “You measure the anterior cornea and use that to determine the IOL, but you ignore the posterior cornea,” he said. To better account for posterior corneal curvature as well as other factors, more and more surgeons are using intraoperative aberrometry, Dr. Berdahl said. Axis rotation occasionally happens in high-risk patients, such as those with large capsular bags or when the anterior capsule does not completely cover the optic edge, said Brad Black, MD, Dr. Brad Black’s Eye Associates, Jeffersonville, Ind., USA. When encountering toric IOL issues, a number of ophthalmic surgeons now use a website called the Toric Results Analyzer (www. astigmatismfix.com) that was developed in the past year by Dr. Berdahl and David Hardten, MD, Minneapolis, Minn., USA. By comparing the toric IOL to the patient’s current manifest refraction, the site can help determine if a rotation would decrease residual astigmatism. The site also provides the necessary amount of rotation. It takes good judgement to determine the value of performing postop fixes, Dr. Black said. “If a patient is happy and has good vision, we’re hard pressed to intervene even if the IOL axis is not perfectly aligned with the intended axis,” he said. AT A GLANCE • Patient expectations are higher with premium IOLs, provoking the need to reduce postop refractive surprises in advance as often as possible. • Preop measurements with the use of reliable keratometry and modern- day biometry devices can help improve the refractive accuracy with IOL selection. • Surgeons should optimize the ocular surface before surgery to help avoid refractive surprises. • Postop refractive errors can occur in different forms with toric, accommodating, and multifocal IOLs. • Surgeons should especially take caution when implanting premium IOLs in patients with previous refractive surgery.