EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/76185
44 EW SECONDARY FEATURE February 2011 Emmetropia July 2012 Zoning in on emmetropia for cataract patients by Maxine Lipner Senior EyeWorld Contributing Editor Pearls for hitting the mark W hen it comes to acceptable outcomes in cataract patients, these days "close" is relegated to playing horseshoes; the fact is, only hitting emmetropia will do. "The last sev- eral decades have been all about safety and efficacy in cataract sur- gery," said Robert H. Osher, M.D., professor of ophthalmology, Univer- sity of Cincinnati, and medical director emeritus, Cincinnati Eye Institute. "The present and the future should be about precision and accuracy, which will lead us to our conquest of emmetropia." Unfortunately, however, not everyone is hitting the mark. In fact, many practitioners think that their outcomes are better than what they really are, according to Warren Hill, M.D., East Valley Ophthalmology, Mesa, Ariz. Dr. Hill pegs outcomes at the .5 D level as somewhere between 72 and 80%. Physicians who are at 90% or above are less than 1% of the database. To help increase the odds, EyeWorld asked leading practitioners for some of their best pearls for hit- ting emmetropia. Formula for success Dr. Hill finds that part of the prob- lem can lay with the lens. The more variables the formula can put to use, the better. He finds that with older two-variable formulas like SRKT or Hoffer Q, most people are going to be outside of the plus or minus .5 D range about 20% of the time. He urged practitioners to steer away from these. "Two-variable, third-generation formulas are all celebrating their 20th birthday," he said. "It blows me away that physi- cians take so little care and yet that's how they're judged by their patients and their peers, by their refractive outcomes, and they're using formu- las that are akin to animal skins and flint knives." Instead, he recom- mended that they move up to the Holladay 2 or the current Olsen formula, which take a greater number of variables into account. Dr. Hill also stressed the impor- tance of tracking outcomes so that practitioners know precisely where they stand. "Otherwise it's like going to sea without a chart and without a rudder," he said. In addition, he urged everyone to optimize their lens constants, something that he is happy to do for them if they visit the physician downloads section of his website (doctor-hill.com/iol- main/formulas.htm), where they can fill out and send in an excel spread- sheet. "I will optimize their lens constants and send them back a report," he said. Turning the toric tide Meanwhile, Dr. Osher stressed the need for excellent biometry and ker- atometry for achieving emmetropia with toric IOLs. To attain this he uses something that he has dubbed the "MELD" technique. "I MELD manual Ks with automated Ks with topography Ks with aberrometry Ks." With the approach he finds he can go from double digit "outliers" to less than 5%. Intraoperatively, Dr. Osher recommended using micro-coaxial phaco. "When you get down to 2.2 mm you are inducing very little cylinder, and the smaller the inci- sion, the more predictable the out- come," he said. Dr. Osher also urged practitioners to use an SMI guidance system (SensoMotoric Instruments, Teltow, Germany) to determine the optimal size of the rhexis. "You need to make the same size rhexis to get the same lens coverage," he said. "Primarily you have to be working reproducibly time after time for a small incision and with a good cap- sulorhexis to prevent the lens from moving in one way or another." To better nail toric lens align- ment or for AK, Dr. Osher uses iris fingerprinting, a software technique that photographs pre-op when the pupil is dilated and all of the land- marks of the iris—the nevi, the crypts, the stromal patterns, and the pigment—so that he knows precisely where he is working during surgery. He finds this far superior to an old- fashioned ink mark, which he pointed out can defuse or even disappear at times. Together with David Chang, M.D., and Steven Slade, M.D., Dr. Osher is working on scanning dynamic wavefront technology dubbed Holos (Clarity Medical Systems, Pleasanton, Calif.) that he sees as holding promise for confirm- ing emmetropia and toric lens alignment in real time. LRIs in the limelight Eric D. Donnenfeld, M.D., co-chair- man, Cornea, Nassau University Medical Center, East Meadow, N.Y., stressed that limbal relaxing inci- sions (LRIs) are an important part of the emmetropic armamentarium. While they can be done under operating room microscopes, Dr. Donnenfeld has found that for small amounts of cylinder under 1 D, these can effectively be done at the slit lamp. The 30-second procedure can improve outcomes immediately. With the slit lamp technique, Dr. Donnenfeld places the phoropter right next to the patient. He rotates the axis to the axis of his incisions and makes his incision over the steeper meridian using a diamond knife. He recently designed a new Dr. Donnenfeld recommends going to www.LRIcalculator.com to determine the best axis to place an LRI LRIs are an important part of the emmetropic armamentarium, according to Dr. Donnenfeld Source (all): Eric D. Donnenfeld, M.D.