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EW San Diego 2015 3 keratometry or biometry readings so we can perform an appropriate procedure. Dr. Donnenfeld: The only time I will not place a toric lens is in a patient with an irregular cornea where I can't determine the right axis or a patient who wants to wear a gas per- meable contact lens postoperatively. What attributes do you seek in a quality toric lens? Dr. Hovanesian: I want a lens that is easy to implant through a reason- able-sized incision and stable after implantation but can be moved in either direction. I like being able to rotate the Tecnis Toric lens (Abbott Medical Optics) at least a few degrees counterclockwise. Dr. Garg: I also like the clear acrylic of Tecnis IOLs, which have no glistenings and low chromatic aberration. Dr. Vukich: The Tecnis Toric is the only available lens meeting Amer- ican National Standards Institute criteria for stability over time. Dr. Donnenfeld: The Tecnis Toric lens has the highest negative spheri- cal aberration and lowest chromatic aberration of any toric IOL available. This provides the highest quality of vision. Dr. Kontos: Additionally, I rarely hear patients complain of a dyspho- topsia-type phenomenon with the Tecnis lens and when they do, it resolves spontaneously over time. Setup for success: Preoperative diagnostics Dr. Donnenfeld: For physicians just getting started with toric IOLs, what key diagnostic steps do you use to drive your toric IOL decision making? Dr. Kontos: It's important to per- form a comprehensive evaluation of their optical system and corneal surface, looking at the tear film qual- ity and discontinuing contact lens wear before making measurements. Surgeons must consider the effects of prolonged contact lens use on topography and corneal astigmatism just as we do for LASIK surgery. A topography device is critical. You cannot rely only on Ks from " Surgeons often obtain irregular measurements and implant a toric IOL using a best guess, leaving the patient unhappy afterward if something like anterior basement membrane dystrophy was not treated. " Francis Mah, MD your manual keratometry or A scan. I also perform several biom- etry measurements and examine them closely. I sometimes use my wavefront analyzer to look at some refractions because it can nail down cylinder much better than manual refraction. Dr. Hovanesian: To evaluate ker- atometry, no single instrument always provides the answer, and confidence comes with time. Be- ginning surgeons should track their outcomes and compare them with preoperative measurements. A good tear film is essential in obtaining accurate measurements. If your measurements are variable, chances are you don't have a good tear film. Topography is critical in ruling out forme fruste keratoconus or other ectatic disorders. Dr. Donnenfeld: I employ all of these measurements and ensure they sup- port each other. When they don't, I use the topography and draw a straight line through the bowtie cylinder and use that as the axis of the cylinder. I usually rely on manual Ks or the IOLMaster (Carl Zeiss Meditec, Jena, Germany) for magnitude of cylinder. Peer-review research shows that an IOLMaster or LENSTAR (Haag-Streit USA, Mason, Ohio) is probably as accurate as anything else we use, but we must confirm it with multiple measurements using different technology. Dr. Garg: If there is disagreement with the various modalities, I sug- gest that surgeons ask the patient to return a couple weeks later to check them again. Dr. Mah: It's also important to look at corneal issues such as Salzmann's nodules and especially anterior basement membrane dystrophy. Surgeons often obtain irregular measurements and implant a toric IOL using a best guess, leaving the patient unhappy afterward if some- thing like anterior basement mem- brane dystrophy was not treated. Dr. Donnenfeld: When measure- ments are not uniform, my first thought is ocular surface disease. I manage the ocular surface and repeat the testing in 2 weeks, which overwhelmingly resolves the problems. According to the 2014 ASCRS Clinical Survey, some ophthalmolo- gists still use manual and auto Ks to drive their decisions. While this is reasonable, optical biometry devices such as the IOLMaster and LENSTAR provide very accurate keratometry. Dr. Kontos: If you decide to provide toric IOLs, you need to commit to having the equipment you need to provide that service properly. Some things like intraoperative aberrom- etry are not needed to get great results, but I think a topographer is an important tool to have. Dr. Donnenfeld: How important is it for surgeons to measure their SIA at the time of cataract surgery to optimize toric IOL results? Dr. Mah: I think it's important, and you can use your past 10 or 20 cases to determine your SIA. It helps sur- geons make decisions and achieve better outcomes. Dr. Donnenfeld: It's very important to enter your SIA into the toric IOL calculation because it can be very variable and affect the magnitude of the cylinder being corrected. More importantly, with vector analysis it can throw off the axis of your toric IOL by as much as 15 degrees. Dr. Hovanesian: When you're refining your results, this makes all the difference. Warren Hill, MD's free online tool allows you to place your incision anywhere you like and calculates the SIA at any axis. Dr. Donnenfeld: Because of posterior corneal cylinder, most patients have less with-the-rule and more against- the-rule astigmatism than we mea- sure. That allowed us to change our toric IOL calculations. Do you calcu- late this with a device or estimate it based on Dr. Koch's work? Dr. Mah: A number of tomography units help analyze posterior corne- al and total corneal astigmatism. However, Dr. Koch's nomogram is helpful for those who don't have a tomographer and only have a topographer. Also, newer calculators like the Barrett IOL calculator, which is available on the ASCRS website, incorporate that information.

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