NuLens
What It Is
The NuLens (NuLens, Ltd., Herzliya Pituah, Israel) is composed of two pieces. The first is a HEMA plate that is placed on top of the collapsed capsular bag after cataract removal. The second is a rigid haptic system containing a soft silicone gel center that is placed atop the HEMA plate and is held in place by patented sulcus fixation haptics. The rigidity of the haptics creates an effective reference plane that permits the deformation of the silicone gel as the HEMA plate is pressed anteriorly by the movement of the capsular diaphragm (consisting of the ciliary processes, zonules, and collapsed capsular bag). The anterior and posterior pressures displace the soft silicone forward. Power is generated in accordance with the forces developed by the ciliary muscles in response to the naturally occurring blur stimulus for accommodation.
Status
The NuLens is in development. NuLens, Ltd. plans to initiate clinical trials this year with the goal of European regulatory approval in 2009 and US Food and Drug Administration approval by 2012. The company is currently evaluating the possibility of placing the haptic system in pseudophakic eyes in order to restore accommodation to patients who have received traditional IOLs.
SYNCHRONY DUAL OPTIC ACCOMMODATING IOL
What It Is
The one-piece Synchrony Dual Optic accommodating lens (Visiogen, Inc., Irvine, California) features a high-powered anterior optic connected to a minus-powered optic by haptics that have a spring-like action. According to the company, the lens' mechanism of action is based on the classic Helmholtz theory of accommodation. For distance vision, the two optics rest close together. When the patient focuses on a near target, the ciliary body releases tension on the capsular bag and zonules, which translates into forward movement of the front optic causing an increase in effective IOL power. As the ciliary body relaxes, tension on the capsular bag brings the front optic back to the resting state, thus returning emmetropic distance focus.
Status
The Synchrony received the Conformité-Européenne (CE) Mark in June 2006. Postmarketing research studies to further evaluate the lens are currently under way in Europe, Canada, and Latin America. In November 2007, Visiogen, Inc., announced that the enrollment for a phase 3 FDA clinical trial was closed. Investigators will evaluate the Synchrony's safety and efficacy as well as patients' potential for functional near, intermediate, and distance vision with the lens. The study includes more than 300 patients at 20 investigational sites in the United States. The company is currently focusing on follow-up and the future submission of a premarket approval application.
TETRAFLEX
What It Is
The Tetraflex IOL (Lenstec, Inc., St. Petersburg, Florida) has a vaulted anterior optic surface and soft, pliable haptics. The idea behind the design is to provide patients with good near vision and excellent intermediate and distance vision. The IOL's proposed mechanism of action is the combined effect of the lens' movement and the bending of the optic as vitreous is displaced during accommodation.
Status
The Tetraflex received the CE Mark in 2004. The IOL has been approved in Australia since 2006, and it was approved in China and Taiwan in 2007. At press time, Lenstec, Inc., had nearly completed enrollment for a phase 3 US FDA clinical trial.
