EyeWorld Asia-Pacific December 2013 Issue

December 2013 13 EWAP FEAturE the market. Surgeons would also like more evidence to show that its use can improve surgical outcomes with toric IOLs. At least one study presented at the ASCRS•ASOA Symposium & Congress in San Francisco demonstrated exactly how intraoperative aberrometry helps. Robert J. Cionni, MD , medical director, The Eye Institute of Utah, and adjunct clinical professor, John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA, said he was already getting good results with his aberrometer for toric IOL patients, but he still sometimes encountered refractive surprises. Holos technology is that it’s an entirely new method of performing wavefront aberrometry,” he said. “Traditional wavefront applications in ophthalmology have been based either on Hartmann–Shack or Talbot–Moire technology. Clarity essentially came up with a different streamlined technology to measure and calculate the wavefront in a much shorter amount of time. As a result, the operating surgeon can look at a display screen in the OR at any given moment and see the actual refraction instantaneously and continuously in real time.” Dr. Chang likens the Holos aberrometry technology to watching a video instead of looking at snapshots. “For example, you will have a quantitative (numerical refraction) and qualitative (linear indicator of cylindrical amount and axis) display that you can monitor immediately before and after you make an incision. With a toric IOL, you can rotate the lens and instantaneously see the refraction in real time. The qualitative display will permit us to dial the IOL right into the optimal position,” he said. Dr. Chang sees this technology as potentially eliminating the need to mark the eye for toric IOLs— something that surgeons who have used VerifEye also noted. “We would use preoperative keratometry and topography to decide with the patient if astigmatism correction is needed or desired. Then we would use intraoperative aberrometry to confirm the amount of toric correction and the axis at which to orient the IOL,” he said. EWAP Editors’ note: Dr. Chang has financial interests with Clarity and Calhoun Vision. Drs. Cionni and Tyson have financial interests with WaveTec. Drs. Cionni and Fisher have financial interests with Alcon (Fort Worth, Texas, USA/Hünenberg, Switzerland). Contact information Chang: +1-650-948-9123, dceye@earthlink.net Cionni: +1-801-263-5732, rcionni@theeyeinstitute.com Fisher: +1-850-784-3937, bfisher@eyecarenow.com Tyson: +1-856-691-8188, sydtyson@comcast.net Views from Asia-Pacific Samaresh SRIVASTAVA, MD Consultant, Raghudeep Eye Hospital Gurukul Road, Ahmedabad, India 380052 Tel. no. +91-79-27490909 Fax no. +91-79-27411200 samaresh@raghudeepeyeclinic.com I nspite of widespread use of toric IOLs for addressing preoperative corneal astigmatism, potential factors for inaccuracy remain, foremost of which are ability to determine the amount of astigmatism and the ability to mark the reference axis for alignment of the IOL. With the development of intraoperative aberrometry systems, there is promise for greater precision and predictability by addressing both these issues. ORA, Holos and other upcomingintraoperative aberrometry systems allow the surgeon to evaluate total astigmatism (including both the anterior and posterior corneal curvature, as well as the effect of the incision) in the eye in a real-time manner following lens removal. A major advantage of intraoperative aberrometry is that it eliminates the need for preoperative marking, and thus not only shortens the time, but also negates the variability that may often be associated with these procedures. Because the aberrometry measures along the patient’s visual axis, it will be more accurate in predicting refractive outcome than technologies that measure on the pupillary center, such as keratometry and topography techniques. Further, the surgeon can also tweak their toric IOLs following implantation intraoperatively by looking at the manifest refraction. However, there are a few caveats that surgeons should keep in mind when using these intraoperative aberrometry systems. As has been pointed out, maintaining a closed chamber is crucial. It is also very important to make sure that there is no retained viscoelastic behind the IOL which can later change the effective lens position. These systems cannot predict postoperative changes in corneal curvature induced by incision healing and incision distortion. Therefore, ensuring a pristine incision with minimal manipulation and distortion remains very important to achieve precise postoperative outcomes. In conclusion, intraoperative aberrometry promises to enhance and further improve outcomes with toric and multifocal toric IOLs, and with many such systems on the horizon, it will only improve refractive outcomes. Editors’ note: Dr. Srivastava has no financial interests related to his comments. That led him to give the topic some further investigation. The study he presented included 65 eyes scheduled for cataract surgery with toric IOL implantation. All eyes had at least 1.5 D of keratometric astigmatism. He used a standard toric IOL nomogram to select the initial cylinder power and marked the steep axis prior to surgery. Then, after phaco, he used ORA to measure the aphakic refraction. Dr. Cionni also used ORA for pseudophakic measurements and to confirm the correct position of the lens implantation. In 55% of the eyes studied, or 36 cases, ORA recommended a cylinder power change, Dr. Cionni said. It recommended a power decrease in 27 cases and an increase in nine cases. The average cylinder reduction was 84%. Dr. Cionni concluded that the ORA improved results with the toric IOLs. Moving to the next aberromet- ric level The ORA is undergoing a hardware update called VerifEye that surgeons believe will further strengthen what it can offer in the OR. VerifEye can provide real- time feedback about the patient’s refractive state. “This is in contrast to the previous system, which captured a series of physician- commanded static measurements to assess the refractive state of the eye,” said Dr. Fisher, who tested out VerifEye. It also helps surgeons monitor the effect of toric IOL lens rotation and the effect of limbal relaxing incisions as they are created, he added. Dr. Tyson has also tested VerifEye. “Prior to VerifEye, it wasn’t as easy to determine when that eye was stable enough to get an acquisition. The lid speculum, ocular surface, and IOP could affect it,” he said. Dr. Tyson believes the VerifEye hardware update is a timesaver that will lead to improved outcomes. “VerifEye incorporates a new processor that allows for faster and more accurate results,” Dr. Fisher said. Dr. Cionni said his experience with VerifEye anecdotally shows that 94% of patients are within a half diopter of their target spherical refraction. “Those are truly LASIK- like results,” he said. Eyeing the Holos wavefront aberrometer Another wavefront aberrometer under development is the Holos (Clarity Medical Systems, Pleasanton, Calif., USA), Dr. Chang said. Dr. Chang has been involved in developing the first clinical prototypes, and the first marketable models are expected later this year. “What is exciting about the