Eyeworld

EW FEATURE 36 hole optics, according to Kevin L. Waltz, M.D., Bloomington, Ind. "What's unique about that is that every eye doctor is very familiar with pinhole optics," Dr. Waltz said. "But we've never surgically im- planted pinhole optics." Robert P. Rivera, M.D., Salt Lake City, who worked on FDA stud- ies of the device, sees implantation of the KAMRA in the cornea as opening a new door for presbyopia correction. "It involves a new type of technology that hasn't been ap- plied to any great degree, and that is placing this implant within the lay- ers of the corneal tissue for the treat- ment of presbyopia," he said. Until recently one component that was a challenge with the KAMRA was centration. "This is ac- tually quite important," Dr. Rivera said. "The idea is that if you have a good system of centering the im- plant, the light rays going through the pinhole will be properly fo- cused." Dr. Waltz, who also worked on U.S. studies with the KAMRA, agreed that proper centration is critical. "We thought that there was a toler- ance of about 500 microns, plus or minus, when we started the studies," he said. "After we had been doing them, we went back and looked at centration versus acuity and we dis- covered that the tolerance is really 200 microns—that is difficult for a human to achieve without assis- tance." The system now has a new im- plantation device, the AcuTarget system, which marks the proper placement position for the practi- tioner. "We measured and found that it was [accurate] within 1 mi- cron," Dr. Waltz said. Dr. Knorz described the AcuTarget system as comprised of two key components. The first is a measurement unit. "It takes a pic- ture of the cornea and the adjacent conjunctiva and measures the axis of corneal astigmatism, the position of the pupil, and the position of the corneal reflex," Dr. Knorz said. A second component allows the practitioner to visualize where to place the KAMRA inlay, with either an LCD monitor or a display built right into the operating room micro- scope. "The system is fed with the image taken with the first unit and it compares it to the actual image under the laser," Dr. Knorz said. "It shows the actual position of the KAMRA inlay and the planned posi- tion." Considering outcomes SIM-LASIK outcomes with the KAMRA inlay have been very prom- ising. Dr. Tomita currently has data on 2,271 cases out to 16 months. Pre-op, these patients who also un- derwent SIM-LASIK had a mean vi- sual acuity of 20/125 and an uncorrected near acuity of J6. "Post- operatively uncorrected distance vi- sual acuity becomes 20/20 and uncorrected near vision is at J2," he said. Dr. Knorz finds that the out- comes with the KAMRA itself, which is typically placed in one eye, sur- pass simple monovision at both dis- tance and near. "At distance patients will see like a –0.5 D myope and not –1 D because of the pinhole effect," he said. "The effective near add will be about –2 D." Quality of vision with the KAMRA is slightly lower than in em- metropia but much better than in simple monovision with a target re- fraction of –1.25 D. "There is also a little bit of glare and halos at night due to light scatter, so patients have to be informed about this," Dr. Knorz said. Dr. Rivera opted to have the KAMRA implanted in Japan and called the experience phenomenal. February 2011 What's ahead in 2012 December 2011 KAMRA continued from page 35

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