EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/422211
31 EW REFRACTIVE SURGERY December 2014 "These machines are quite reliable and if you run them right and learn how to use them, they can give valuable information," he said. Both physicians recommended rechecking readings if a particular IOL is planned and the intraopera- tive reading is "way off." Dr. Durrie said up to 3–5% of the readings will not be consistent with preoperative measurements. "It usually means you need to consistently look at your own tech- nique," he said. "Are you very pre- cise so your intraocular pressures are the same? Is your speculum always in the same place? Is your capsulor- hexis always nice and precise? There was room for variability in all those before because we weren't taking readings in the OR." EW Editors' note: Dr. Clinch has no financial interests related to this article. Dr. Durrie has financial interests with WaveTec Vision. Contact information Clinch: tclinch@edow.com Durrie: ddurrie@durrievision.com If there is any doubt about the accuracy, take more than one mea- surement and look at the wavefront patterns to make sure they make sense and are consistent. New skill sets As with most technology, there is a learning curve and new skill sets needed, Dr. Durrie said. Of para- mount importance, however, is ensuring the device is calibrated correctly. "If you forget to calibrate the machine properly, you're not going to get good data out of it," he said. Learning how to best use the device is another "soft skill," he added. In the OR, he's convinced the most important reading to get is the aphakic one "to help surgeons make sure they're putting in the right IOL. Once they've got the IOL in the eye, since the capsule hasn't had time to contract, the effective lens posi- tion is not something that can be measured by an aberrometer. A lot of times the pseudophakic sphere cal- culation will be off especially if the lens is not put in the right position by having the right amount of fluid in the eye," he added. "This is going to be a new skill set for people." Learning curve pearls Dr. Clinch recommended getting wavefront readings before any other diagnostics when the patient arrives in the office. For cataract and refractive patients, office visits often include a battery of tests. Many of these tests cause patients to suppress their blink reflex, creating dryness of the ocular surface. This is especially relevant in cataract patients where the majority of them have pre-exist- ing dry eyes. Dr. Clinch tries to per- form biometry testing on a different day than the initial consultation for cataract surgery. "We recommend our patients use artificial tears on a regular basis prior to their visit for diagnostic testing. To determine the accuracy of preoperative aberrometry testing, we compare the refraction obtained by manifest refraction and wavefront measure- ment. Since wavefront aberrometry measures both lower and higher order aberrations, the trick is to compare the refraction obtained by manifest refraction with the wavefront refraction of a similar pupil size," he said. For example, if the manifest refraction was performed at approx- imately a 4-mm pupil size, compare the measured refraction of the aber- rometer at a similar pupil size, and see if the refraction you're getting through your wavefront analysis mimics the refraction from the pa- tient. "If they correlate well, I then feel more confident in using the higher order aberrometry analysis in planning my IOL selection," Dr. Clinch said. During the first few weeks, surgeons may notice outliers in the intraoperative measurements. Until the readings start to gel a bit more cohesively, Dr. Durrie recommends not putting total faith in the intra- operative readings. "While you're still learning the nuances of the device and how best to use it in your own hands, relying totally on the new device makes no sense," he said. "Cataract surgeons have been performing these surgeries for years, and the fall back is to place the IOL you had chosen preoperatively." As time goes on, subtle differ- ences will emerge and "once the readings are more consistent, you'll rely on it more and more," Dr. Durrie said. "Don't get discouraged. I think some people might get one bad reading and say, 'I don't trust this.' During the learning curve you're going to have some odd readings. In the beginning, use it as an additional piece of information," Dr. Durrie said. The pseudophakic measurements are very accurate for toric correction. With the number of toric IOLs now being used, it is very valuable to make sure the lens is properly aligned. Dr. Clinch now uses intraopera- tive analysis as an integral step in all cataract procedures for premium IOL and post-refractive surgery patients. "Using intraoperative aberrometry to refine my biometry calculations, I can now achieve comparable outcomes in my post-refractive and previously unoperated eyes. It gives me the confidence to implant multifocal IOLs in the majority of my post-refractive patients as long as the preoperative topography and aberrometry do not demonstrate substantial corneal aberrations," he said. "One of the other challenges will then be trying to get a good reading after [patients'] eyes have dried out from multiple dye tests and suppressing the blink reflex," he said. Poor information preoper- atively will result in equally poor agreement intraoperatively. Things that could affect an intraoperative reading include the lid speculum, the tear film, or the intraocular pressure, Dr. Durrie said. "Especially in the pseudophakic state, it's important the lens be in the physiologic position and well centered and not tilted before you take the reading," Dr. Durrie said. Most importantly, Dr. Durrie advises surgeons not to stress if the first few sets of readings are incon- sistent between intraoperative and preoperative readings. VII ÅÂÐÎ-ÀÇÈÀÒÑÊÀß ÊÎÍÔÅÐÅÍÖÈß ÏÎ ÎÔÒÀËÜÌÎÕÈÐÓÐÃÈÈ 27–29 àïðåëÿ 2015 ã. ÅÊÀÒÅÐÈÍÁÓÐÃ ÂÒÎÐÎÅ ÑÎÎÁÙÅÍÈÅ ÎÐÃÀÍÈÇÀÒÎÐ Åêàòåðèíáóðãñêèé öåíòð ÌÍÒÊ «Ìèêðîõèðóðãèÿ ãëàçà» ÎÐÃÊÎÌÈÒÅÒ Ðîññèÿ, 620149, ã. Åêàòåðèíáóðã, óë. Àêàäåìèêà Áàðäèíà, 4à Òåëåôîí: (343) 231-01-59 Ôàêñ: (343) 231-00-03 Å-mail: eakonauka@gmail.com www.eyeclinic.ru Äèñêóññèîííûå âîïðîñû ñîâðåìåííîé îôòàëüìîõèðóðãèè