EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/76185
July 2012 Emmetropia The Physician's PERSPECTIVE knife, dubbed the Donnenfeld Diamond Knife (Accutome, Malvern, Pa.), that has 15 degrees of angula- tion to match the curvature of the cornea. Outcomes have been prom- ising. "I find that very routinely pa- tients get one to two lines of visual improvement of uncorrected visual acuity," he said. He makes it a prac- tice to offer the option to all who would benefit. "I would say only about half of my patients avail themselves of this opportunity, but the patients who do and even those who don't appreciate that I'm mak- ing an effort to do everything that I can to optimize their visual acuity," Dr. Donnenfeld said. To determine the best axis to place an LRI, Dr. Donnenfeld recom- mended going to www.LRIcalcula- tor.com (Abbott Medical Optics, Santa Ana, Calif.). "That allows doctors to input the pre-existing astigmatism, the cataract surgery astigmatism, and that calculates the new axis of where to place the limbal relaxing incision," he said. Noel Alpins, M.D., medical director, New Vision Clinics, Melbourne, Australia, developer of the Alpins method of astigmatism analysis, likewise recommends LRIs for enabling more patients to reach emmetropia. In many cases he be- gins with the phaco incision itself. "If they have a small amount of astigmatism, I can reduce that just by placing my phaco incision on the steepest meridian," he said. "I don't do it temporally—I do it at whatever meridian around the eye that I can." With this method he finds that he can reduce astigmatism by about .5 D. For those with 1-2 diopters of astigmatism, Dr. Alpins pairs LRIs with his phaco incision technique. "If you're doing a phaco incision on the steepest meridian all that you have to do is an LRI, 180-degrees on the other side of the eye," he said. "You double up on the effect of the phaco incision and you can correct up to 2 D of corneal astigmatism." He finds this covers 80-90% of astigmatic patients. To gain a little extra bit of effect, he recommended doing a larger phaco incision than otherwise. "Normally I do about a 2.2 mm, but I'm going to bring that up to 3 mm just to get the extra flattening effect of the incision," Dr. Alpins said. "I might even move it slightly closer to the center of the cornea to increase its effect." For patients with more than 2 D of astigmatism he recommended using a toric IOL or performing LASIK after cataract surgery. Even with a toric lens, Dr. Alpins pairs this with the flattening effect of an incision, using, for example, a 2.5 D toric IOL together with the phaco incision to correct 3 D of astigma- tism. In order to be most effective, he recommended knowing the surgi- cally induced astigmatic effect of your incisions at each particular meridian. He offered the use of his free Assort toric calculator module (www.assort.com) to determine the best toric IOL power. This will enable physicians to do a generic calculation for any implant. In addition to offering a precision calculation, the site will enable practitioners to manage a refractive surprise if one does occur. "They'll be able to calculate whether the implant power was too strong or too weak or whether the implant is functionally on the correct meridian," Dr. Alpins said. Overall, Dr. Donnenfeld stressed the importance of handling astigma- tism in hitting emmetropia. "Ap- proximately 75% of patients have .5 D or more of astigmatism," he said. "So if you're not managing astigma- tism, you're not optimizing your patients' visual acuity following cataract surgery." EW Editors' note: Dr. Alpins is the developer of the Assort program. Dr. Donnenfeld has financial interests with Alcon (Fort Worth, Texas) and WaveTec Vision (Aliso Viejo, Calif.). Dr. Hill has financial interests with Alcon and Haag-Streit (Koeniz, Switzerland). Dr. Osher has no financial interests related to this article. Contact information Alpins: 61-408-343-977, nalpins@unimelb.edu.au Donnenfeld: 516-446-3525, eddoph@aol.com Hill: 480-981-6111, hill@doctor-hill.com Osher: 800-544-5133, rhosher@cincinnatieye.com In today''s s economic clima onomic climate... I trust my business to ASOA. www.ASOA.org