EyeWorld Asia-Pacific September 2014 Issue

10 September 2014 EWAP FEAturE variable effective lens position, so it’s a bit harder to hit the spherical target,” he said. “The good thing is they’re more forgiving because they’re going to accommodate through some of that refractive error.” A little myopic error will enable them to read more easily, Dr. Berdahl said. He estimated that accommodative lens patients can tolerate about 0.75 D of cylinder and be satisfied. “Still, removing that cylinder would certainly improve their quality of vision,” he said. The fact is, the more astigmatism patients have preop, the greater the chance that they are going to need some sort of enhancement postop, Dr. Berdahl said. Also, depending on the IOL type, patients may not be able to tolerate as much error. He has found that with multifocal IOLs, the residual astigmatism tends to be bothersome, whereas with accommodating lenses, missing the spherical target tends to be the issue. A patient’s expectations can also factor in. “I don’t ever promise that I’m going to get someone out of their glasses for any and all activities,” Dr. Berdahl said. Nonetheless, given how much patients are spending on these lenses, he emphasized that patients should be hopeful about more functionality in their lives and greater freedom from spectacles. “Once that pact is made between the surgeon and the patient, the surgeon has a responsibility to do everything that he can to make that patient as happy as possible with the vision,” Dr. Berdahl said. Scott M. MacRae, MD , professor of ophthalmology and visual science, University of Rochester, Rochester, NY, U.S., has found that about 20% of patients need an enhancement. In his experience, enhancements are slightly more common in high myopes, hyperopes, and in postrefractive eyes because these are harder to predictably treat. Dr. MacRae also has found that for astigmatism refinement, other factors besides residual amount may play a role. For example, those with large pupils may be more sensitive to astigmatism, he said. “A 6-mm pupil is about twice as sensitive, with about twice as much image quality reduction as with a 3-mm pupil,” Dr. MacRae said. Also, the orientation of the astigmatism is important. “The brain is tuned to vertical and horizontal lines,” he explained. “There will be about a 50% reduction in image quality if the astigmatism is oblique because the brain isn’t tuned to looking at oblique patterns as keenly as it is to horizontal and vertical patterns.” To determine if any enhancement is needed, he places the correction in a pair of trial lenses and asks patients whether this improves their vision, while they are in the exam lane. “If they notice that it improves their vision, I’ll go ahead and treat; if they don’t notice significant improvement, I recommend not treating,” he said. Dr. MacRae thinks that refractive premium lens treatment is evolving and that surgeons are becoming more attuned to the fact that they need to do enhancements to optimize vision. “I look at doing premium lenses as entering into a contract with patients, telling them that I’m going to try to get them the very best vision that they can achieve without putting them in harm’s way,” Dr. MacRae said. “For premium surgeons to be successful, they have to commit to that type of approach.” Enhancement restrictions However, not all cataract practitioners are in a position to correct residual refractive error, he said. “One of the problems with the premium lens practice is that most general cataract surgeons aren’t equipped or psychologically ready to commit to fully optimizing patients’ vision because they don’t have the capability of doing either LASIK or PRK to fully enhance them,” Dr. MacRae said. But a laser vision enhancement is not the only answer. Another viable, potentially less-intimidating option can be the use of mini- PRK, he said. With the mini-PRK technique, less epithelium needs to be removed since the treatments and transition zones are relatively small, Dr. MacRae explained. “That gives the patient less pain, quicker visual recovery, and less likelihood of having problems with re-epithelialization,” he said. “It’s a perfect option for a cataract surgeon who wants to do a small enhancement.” Dr. Schallhorn urges practitioners to keep in mind that for residual astigmatism, an astigmatic keratotomy might be a good choice too. The lens could be rotated, exchanged for a different power, or a piggyback lens can be put in, Dr. Schallhorn said. “It’s not a jump right to laser vision correction,” he said. Dr. Berdahl agreed that lack of access to laser vision correction is one factor hampering enhancements. He also thinks that some physicians are approaching premium outcomes from the point of view that they ultimately want to “do no harm.” “You can’t do any harm by not doing anything,” he said. “But you may not get the ball into the end zone either.” Going forward, Dr. Berdahl thinks that use of intraoperative aberrometry and the latest generation IOL calculations will help diminish the need for enhancements. In addition, the lenses themselves may play a role. “Future technology like the Light Adjustable Lens [Calhoun Vision, Pasadena, Calif., U.S.] may make it so that we plan on building an enhancement in for everyone,” he said. EWAP Editors’ note: Dr. Schallhorn has financial interests with Abbott Medical Optics (Santa Ana, Calif., U.S.). Dr. Berdahl has financial interests with Alcon (Fort Worth, Texas, U.S.) and Bausch + Lomb (Bridgewater, NJ, U.S.). Dr. MacRae has no financial interests related to his comments. Contact information Berdahl: johnberdahl@gmail.com MacRae: Scott_MacRae@URMC.Rochester.edu Schallhorn: scschallhorn@yahoo.com Paying - from page 8