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EW REFRACTIVE 66 November 2017 on any one technology alone to examine a patient, choose an IOL, or orient a toric IOL. Using at least three reliable corneal measurements, understanding the posterior corneal contribution to astigmatic power, and developing a systematic mark- ing and alignment strategy will lead to reliable results with excellent patient outcomes. EW References 1. Holladay JT, et al. Calculating the surgi- cally induced refractive change following ocular surgery. J Cataract Refract Surg. 1992;18:429–43. 2. Holladay JT, et al. Evaluating and reporting astigmatism for individual and aggregate data. J Cataract Refract Surg. 1998;24:57–65. 3. Holladay JT, et al. Analysis of aggregate sur- gically induced refractive change, prediction error, and intra ocular astigmatism. J Cataract Refract Surg. 2001;27:61–79. 4. Koch DD, et al. Surgically induced astigma- tism. J Refract Surg. 2015;31:565. Editors' note: Dr. Fram has financial interests with Alcon. Contact information Fram: nicfram@yahoo.com the Baylor nomogram, or presum- ably direct measurements such as on the Galilei (Ziemer, Port, Switzer- land), Cassini (i-Optics, The Hague, the Netherlands), or Pentacam (Ocu- lus, Arlington, Washington). "There are different ways of effectively measuring astigmatism," Dr. Fram said. "Placido imaging is essentially a 'quality check,' and recent advancements in biometry technology have resulted in repro- ducible and reliable K readings. The IOLMaster 700 [Carl Zeiss Meditec, Jena, Germany] and the LENSTAR [Haag-Streit, Koniz, Switzerland], can provide measurements that are more accurate than ever. Not everyone has every type of technology in his or her office, and many will suffice. The Galilei is particularly impressive because it incorporates Placido imag- ing, total corneal power, and pa- chymetry, giving you everything in one machine. The Cassini is also an exciting device in that it uses LED lights, ray tracing, and Purkinje im- ages to measure total corneal power (and most recently ocular surface disease) and is extremely helpful in understanding the contribution of posterior corneal astigmatism." Intraoperative decision making The third consideration in toric IOL surgery concerns intraoperative decisions, imaging, and alignment. Many IOL companies now offer toric IOLs. Once a suitable IOL is selected, marking the cornea for toric IOL placement is of primary importance, and there are many new devices that offer digital marking that can guide the surgeon during IOL alignment. "The latest technology offers tools that employ digital marking using anatomical reference points such as the scleral and limbal vessels or the iris fingerprinting," Dr. Fram said. "With the Verion [Alcon, Fort Worth, Texas], the reference imaging is transferred, for instance, to the LenSx femtosecond laser [Alcon] and directly into the operating room. Several different technologies offer digital marketing as well and allow the surgeon to place the IOL at the right position in the eye and check the position intraoperatively. The Callisto [Carl Zeiss Meditec] uses digital marking intraoperatively to assist with capsulorhexis sizing and toric alignment. Intraoperative aber- rometry [ORA, Alcon] offers an abil- ity to record the aphakic refraction in real time. This essentially takes the anterior and posterior corneal power contribution into consider- ation—without a direct measure- ment—and is often very consistent with the Baylor nomogram, current toric calculator adjustments, and the Cassini, in my experience. This adds another layer of reliability during toric IOL alignment. "There is potentially more excit- ing technology on the horizon that will link the Verion technology with ORA steep axis alignment intraop- eratively [VerifEYE Lynk, Alcon]. However, a reference mark on the patient should always be applied to the cornea or with iris/scleral land- mark imaging preoperatively in the upright position in the event that the technology fails intraoperatively. Robert Osher, MD, refers to this as 'a surgeons parachute,' and it is a point that cannot be emphasized enough," Dr. Fram said. Dr. Fram said the key to suc- cessful surgery begins with a careful ocular surface exam, understanding the various diagnostic technologies and limitations, and knowing when to best implement them. It would behoove a surgeon to not depend Torics continued from page 64 800.354.7848 TOLL FREE IN THE USA | +1.859.259.4924 WORLD WIDE | stephensinst.com S9-2070 S9-2060 S9-2065 As we celebrate 40 years of service to the ophthalmic community, we recognize those doctors who have grown along with us. Just like our instruments, our reputation for value, service and reliability has been crafted to last a lifetime. "I have used Stephens ophthalmic instruments since I went into practice—forty years ago. When I need new microsurgical instruments, I look to Stephens first." JOHN E. DOWNING, MD Bowling Green, Kentucky © 2017 Stephens Instruments. All rights reserved.

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