Figure 9-8 Example of an IOL with a flexible hinge in the haptic at the proximal end and a polyamide footplate at the distal end. The footplate functions to maximize contact with the capsule and ciliary body, and the hinge transfers the horizontal force into an anteroposterior movement of the optic. (Courtesy of Eyeonics.)
Findl O, Kiss B, Petternel V, et al. Intraocular lens movement caused by ciliary muscle contraction. J Cataract Refract Surg. 2003;29(4):669–676. Langenbucher A, Huber S, Nguyen NX, Seitz B, Gusek-Schneider GC, Küchle M. Measurement of accommodation after implantation of an accommodating
posterior chamber intraocular lens. J Cataract Refract Surg. 2003;29(4):677–685.
Other IOL Innovations on the Horizon
In contrast to single-plate accommodating IOLs, which are thought to work via lens effectivity secondary to a change in the position of the optic in the eye, lenses with dual-optic elements connected by a system of springlike struts are undergoing clinical investigation (eg, Synchrony lens [Visiogen, Irvine, CA]; Fig 9-9). During accommodation, the lens system confined within the capsular bag undergoes a change in the separation of the 2 optics, resulting in increased effective lens power. The lens can be implanted into the eye through a 3.5-mm incision.
Figure 9-9 Clinical photograph of implanted dual-optic accommodating IOL, which has a high-plus anterior optic connected by spring haptics to a posterior optic with variable negative power. The three-dimensional design mimics the natural lens, and its response to the contraction and relaxation of the ciliary muscle increases paraxial power and provides accommodation.
(Courtesy of Ivan Ossma, MD)
Another type of lens is made from a thermoplastic acrylic gel that can be customized to any size, shape, or power specified by the physician (eg, SmartLens; Medennium, Irvine, CA). The hydrophobic acrylic material is chemically bonded to wax, which melts inside the eye at body temperature and allows the predetermined shape and power of the material to emerge. Theoretically, compression of this pliable lens by the capsular bag would allow adjustment of its effective power in a manner similar to the way the crystalline lens adjusts. Other examples of deformable IOLs in preliminary stages of development are the FlexOptic (Abbott Medical Optics, Santa Ana, CA),
FluidVision IOL (PowerVision, Belmont, CA), and NuLens Accommodating IOL (NuLens, Herzliya Pituach, Israel). The NuLens changes its power rather than its position in the eye. It incorporates a small chamber of silicone gel and a posterior piston with an aperture.
In addition, flexible polymers are being designed for injection into a nearly intact capsular bag after extraction of the crystalline lens through a tiny, laterally placed capsulorrhexis.
The Light Adjustable Lens (LAL; Calhoun Vision, Pasadena, CA) is made from a macromer silicone matrix with smaller, embedded photosensitive molecules that allow for postoperative customization of the power via tunable ultraviolet light treatment (see Chapter 8 for more detail).