EyeWorld Asia-Pacific September 2015 Issue

September 2015 10 EWAP FEATURE Succeeding with toric IOLs by Ellen Stodola EyeWorld Contributing Writer AT A GLANCE • Surgeons should ensure that the patient’s ocular surface is healthy prior to taking any measurements for toric IOLs. • The 3 companies with commercially available toric IOLs (Alcon, Abbott Medical Optics, and Bausch + Lomb) all have online toric IOL calculators. • A number of other toric IOL calculators are excellent resources. Surgeons discuss the preoperative diagnostics they use for toric IOL implantation T here are many things physicians can do to set themselves and their patients up for success with toric IOLs. Preoperative diagnostics are a key factor, and there are a number of measurements and considerations for axis and power when implanting a toric lens. Sumit “Sam” Garg, MD , Gavin Herbert Eye Institute, Irvine, Calif.; John Hovanesian, MD , Harvard Eye Associates, Laguna Hills, Calif.; and Francis Mah, MD , Scripps Clinic, La Jolla, Calif., shared some of their pearls for preoperative management and what they think are the key factors for success. Preoperative diagnostics? Before taking measurements, it is important to address the ocular surface. “First, you need a healthy ocular surface that can yield reliable and repeatable measurements,” Dr. Hovanesian said. In order to ensure that you have this, it is important to manage dry eye preoperatively, and it is also important to recognize other abnormalities, such as anterior basement membrane dystrophy, that could distort the surface and lead to irregular measurements, he said. After taking care of the ocular surface and any other preoperative conditions, Dr. Hovanesian said that he primarily uses corneal topography and optical biometry, which can be accomplished with either the IOLMaster (Carl Zeiss Meditec, Jena, Germany) or LENSTAR (Haag-Streit, Köniz, Switzerland). Manual keratometry can play a role, but it is less widely used because of other methods that are consistent and reliable. “The challenge comes when the results from the two instruments don’t agree either at the axis or the magnitude of astigmatism,” Dr. Hovanesian said. “I think you need to look at both measurements to have reproducible results.” Physicians may want to determine the axis based on topography, and primarily looking at the central 1–2 mm of the cornea will give you the best idea of the magnitude of astigmatism. The IOLMaster may underestimate the magnitude of astigmatism, he said. But he maintained that it is important to look at both topography and the IOLMaster to be sure that your measurements make sense. Either topography or tomography may be necessary for success with toric IOLs. Dr. Garg said it is important to look for agreement between your various diagnostics. “The ocular surface is of utmost importance,” he said. “It is very important to ensure that the ocular surface is without significant dryness/aberration prior to measuring for a toric IOL.” Dr. Mah said that the surgical techniques associated with toric IOLs are the same as what surgeons are already used to. A lot of the equipment used for preoperative diagnostics are technologies that many already have in their practice. The thing that most people do is get optical biometry, he said, which can be done by using either an IOLMaster or LENSTAR. “It helps not only with sphere but also with cylinder because it does help with the keratometry and axis,” he said. Dr. Mah will also get autorefraction with keratometry value because there will be corneal cylinder or lenticular cylinder. What surgeons should operate on from a toric IOL standpoint is the corneal cylinder. Topography is essential in this process. “You want to make sure there’s nothing else going on in the cornea so that it’s not irregular astigmatism that you’re trying to correct,” Dr. Mah said. Driving toric IOL axis and power decisions There are a number of diagnostic tools available to measure IOL axis and to help make power decisions. Dr. Garg uses a number of these tools, including the IOLMaster, OPD III (Marco, Jacksonville, Fla.), and Pentacam (Oculus, Arlington, Wash.). “My IOLMaster determines spherical power and gives me one measurement of astigmatic axis,” he said. Meanwhile, the OPD allows Barrett Toric Calculator Source: Graham Barrett, MD