EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
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56 EW FEATURE February 2011IOLs February 2012 Getting up-close and personal with new accommodative IOLs by Maxine Lipner Senior EyeWorld Contributing Editor AT A GLANCE • The FluidVision uses liquid channels to harness Mother Nature's accommodative forces • With the NuLens, accommodation is counter to that of the patient's natural lens • The two-piece Synchrony lens boasts movement of the front optic • With the Tetraflex lens, higher-order aberrations are the key to near and intermediate vision Profiling new rising accommodative stars T here's a new group of ac- commodative lenses wait- ing in the wings to impress practitioners with their ability to offer near and in- termediate acuity in addition to typ- ical distance. EyeWorld had a heart- to-heart with practitioners already versed in the lenses to find out the intimate details of what gives these lenses their unique personalities. Fluid disposition With traits unlike any of its accom- modative cousins, the FluidVision lens (PowerVision, Belmont, Calif.) closely emulates Mother Nature's ac- commodative mechanism, accord- ing to Louis D. "Skip" Nichamin, M.D., medical director, Laurel Eye Clinic, Brookville, Pa. "The lens was designed with the intent of harness- ing Mother Nature's natural accom- modative forces from the ciliary body expressed through the zonules and capsule to an artificial lens that would have shape changes that are similar and replicate our natural accommodative process," Dr. Nichamin said. This, he noted, is in contrast to the NuLens (NuLens Ltd., Israel), which uses a reverse accommodative process, although it does appear to work. Dr. Nichamin views the way the fluid moves here as remarkable. "The annular peripheral haptics are the reservoirs for the fluid, and as the ciliary body and zonular appara- tus contract and expand, that fluid in the peripheral annular haptics is forced radially through a channel into the center of the lens, causing it The Tetraflex lens Source: Paul J. Dougherty, M.D. to increase its anterior posterior cur- vature," he said. "The fluid moves back and forth naturally through this pliable system." The channels in the lens are completely translucent. He finds that near vision with the lens is promising, offering an av- erage of over 5 D of accommodation in the testing of sighted eyes. In some non-sighted eyes stimulated physiologically, results have been even better, indicating that even greater levels of accommodation are possible. In the next few months, the company will begin European studies. After receiving the CE mark, the company hopes to start FDA tri- als. Antithetical accommodative nature The NuLens is a two-piece accom- modating IOL that is placed out of the bag, according to Steven G. Slade, M.D., Slade & Baker Vision Center, Houston. "The base unit is put in on top of the bag and then a second optic is put in with the hap- tics that fixate in the sulcus," he said. "When the patient accommo- dates, the collapsed bag moves for- ward and pushes the base unit up into the top unit and actually changes the radius of curvature and power." This lens's accommodative mechanism is opposite that of Mother Nature, according to Douglas D. Koch, M.D., professor and the Allen, Mosbacher, and Law Chair in ophthalmology, Cullen Eye Institute, Baylor College of Medi- cine, Houston. He pointed out that in typical accommodation when the ciliary body contracts, it relaxes the zonules, causing the lens to move forward slightly, but more impor- tantly assuring a more spherical shape and an increase in power. The NuLens, however, is different. "This is relying directly on the force of the ciliary body and is not relying on any effect of the capsule, except as tension is created on it as the ciliary The NuLens accomodating IOL Source: I. Howard Fine, M.D. muscle relaxes," he said. "It's proba- bly a more direct transmission of cil- iary muscle energy to the implant." He finds that some neuroadap- tation is required with the lens be- cause accommodation occurs as the ciliary muscle relaxes, not as it con- tracts. Despite this unusual mecha- nism Dr. Koch sees the lens as promising. "So far every challenge they have placed on this theory has passed with flying colors," he said. The lens has been tested in 30 patients so far and has attained be- tween 4-7 D of accommodation, ac- cording to Dr. Slade, who is the trial surgeon. "We are hoping to begin FDA trials this year," Dr. Slade said. "At this current time we have not gotten the CE mark." Dual personality Also with two components, the Synchrony dual-optic lens (Abbott Medical Optics, AMO, Santa Ana, Calif.) is the only other lens besides the NuLens that has been docu- The Synchrony dual-optic lens Source: Abbott Medical Optics The FluidVision IOL Source: PowerVision