EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/176967
54 EW FEATURE February 2011 Refractive challenges and innovations September 2013 Novel continued from page 53 cians could determine where, for instance, the 17-degree meridian is located, he said. In turn, this might ultimately be used for IOL alignment. Calculation component The Verion Reference Unit (left) allows surgeons to creat a blueprint of the optimized procedure for each patient. To help with incision and IOL alignment, the Digital Marker (right) displays patient information and images from the Reference Unit. The Digital Marker can be used with most surgical microscopes. Source: Alcon first part of the system is a photograph that gives the clinician information about the astigmatism," he said. "It also allows for registration of the eye during the surgical procedure itself." The instrument, he explained, is able to determine the location of the limbus and photograph this from memory. "It also recognizes the center of the pupil, something that can be recognized and used later, and it has memory for the peripheral iris details," he explained. "The photograph gives those three pieces of information that can then be used to register the eye during the procedure itself." This enables practitioners to avoid use of ink and other ways of marking the cornea for placement of the toric lens or for that of peripheral corneal relaxing incisions. As Louis D. "Skip" Nichamin, MD, medical director, Laurel Eye Clinic, Brookville, Pa., explained it, the photographs of the front of the eye, made with the former SMI registration component, use landmarks Monthly Pulse T that allow for the creation of a very reliable reference or orientation pattern. This can then be used to determine the position of the target meridian for IOL alignment or for centering limbal relaxing incisions. "Instead of eyeballing and making a mark with a pen at 6 or 12 o'clock, the system through digital overlay will use these reference anatomic landmarks to accurately determine 6, 12, 3, and 9 (o'clock positions)," Dr. Nichamin said. Then with the aid of a 360-degree overlay clini- Dr. Lane described this first component to the Verion system, charged with gathering registration information along with keratometry readings, as essentially a reference unit. Then information gathered, as well as additional data such as axial length obtained with an IOLMaster (Carl Zeiss Meditec, Jena, Germany) or a Lenstar (Haag-Streit, Koeniz, Switzerland), is set into a new formula on the Verion that allows for the determination of the lens and cylindrical power. Dr. Lane views this as another vital part of the system. "For the first time this gives surgeons options to choose various lenses with the (projected) results posted so they can see basically where the patient would land," Dr. Lane said. It shows what would happen if they notch up in power or go down and does the same for cylinder as well, he noted; practitioners then have the ability to select whether they want to overcorrect or undercorrect the patient a bit. Another flexibility practitioners can draw on is that the calculator will allow them to see what happens if they use a toric lens alone, a peripheral relaxing incision by itself, or combine the two, Dr. Lane explained. This is achieved by use of a slide bar on the calculator. "If you slide it all the way to one side it gives you what the power of the Keeping a Pulse on Ophthalmology his Monthly Pulse Survey focused on "Refractive challenges and innovations." A very slight majority of respondents screen patients before laser vision correction with topography. However, almost as many said that they are screening patients with both topography and tomography. If the physicians who responded to this survey were faced with a free cap complication during a LASIK procedure, 66% would handle it by performing PRK. In regard to presbyopia-correcting IOLs, the majority responded that they are implanting the same amount as they did last year. Finally, we asked about the most common reasons that post-refractive surgery patients are unhappy. Two answers had just about the same number of responses: unrealistic goals/expectations and residual refractive error.