Novel IOL changes shape to achieve accommodation

Washington, DC-A novel IOL in development from PowerVision may represent the most promising concept yet for an accommodative implant, said Louis D. "Skip" Nichamin, MD, at the annual meeting of the American Society of Cataract and Refractive Surgery.

The technology is designed to mimic the natural crystalline lens by undergoing a shape change in response to the forces induced by contraction and relaxation of the ciliary body muscles. The implant has been named the FluidVision IOL because the shape change is mediated by internal fluid actuators.

Results from modeling studies completed so far demonstrate that by harnessing natural forces in the eye, it should be able to create an accommodative range of up to 10 D, reported Dr. Nichamin, medical director, Laurel Eye Clinic, Brook-ville, PA.

"Shape change arguably makes better sense than those strategies because it is the most optically efficient way to create accommodation, and currently there is strong scientific evidence from rigorous experimental testing that the FluidVision IOL is very promising technology based on that concept," Dr. Nichamin said.

The FluidVision implant features internal fluid actuators that respond with fluid shift to ciliary body forces. As force is exerted upon an area of the lens by the ciliary body/zonular membrane, fluid is pushed through channels within the malleable lens and results in a change in shape. Fluid movement that occurs with accommodative effort translates into thickening of the lens from front to back so that its anterior curvature and effective power increase to afford near vision. When gaze turns to distance and the ciliary body relaxes, the FluidVision IOL is put on stretch and gets thinner, just like the natural lens.

"It is amazing that up to 10 D of accommodative change can be achieved with this implant design considering it is being modulated by shifts in such incredibly minute volumes of fluid," Dr. Nichamin said.

Now, PowerVision is working to complete a scale model that would be a prototype for human implantation. Based on current estimates, it is possible the first human eye procedures will be performed in late 2006.

That clinical development program is using currently available IOL biomaterials and is focusing on designing a lens that would be handled and inserted like a conventional foldable implant.

"From a practical standpoint, those are major theoretical advantages over the second-generation dual-optic accommodating IOL technology that, because of its bulk and design, presents new challenges in terms of handling, insertion, and the risk of interlenticular opacification," Dr. Nichamin said. "We hope this novel implant will avoid those issues because it will look more like a standard IOL and emulate the human natural crystalline lens in its performance."