Intraocular lens technology has advanced tremendously over the past decade. We now have a variety of foldable, aspheric, multifocal, and accommodating IOLs. There are many more designs in development, and here is a brief overview of some of these special lenses:
Akkommodative 1CU (Human Optics): a 1-piece foldable acrylic lens with 4 flexible haptics, 5.5 mm optic, and 9.8 mm overall diameter. Anterior movement of the optic produces increased power. However, results in Europe have been poor with < 2 D of accommodation.
Tetraflex IOL (Lenstec): an anteriorly vaulted flexible acrylic lens with a 5.75 mm square-edged optic to reduce posterior capsular opacification. It has an accommodative amplitude of 2.4 ± 1.0 D and injects through a 2.5 mm incision. FDA trial 6-month accommodation data shows 100% ≥ 2 D, 69% ≥ 3D, and 44% ≥ 4 D. The lens is currently available outside the United States and is awaiting approval here.
Sarfarazi Elliptical IOL (B&L): a 1-piece foldable lens with 2 optics connected by 3 haptics. The anterior biconvex optic moves 1.9 mm with respect to the posterior concave-convex optic, producing 4 D of accommodation. It has demonstrated 7-8 D in animal eyes.
Synchrony IOL (Visiogen): another 1-piece foldable lens with 2 optics that are connected by spring-like haptics. The 5.5 mm +32 D anterior optic moves 1.5 mm with respect to the 6 mm minus-power posterior optic to produce 3.3 D of accommodation. It can be injected through a 3.7 mm incision.
FlexOptic Lens (Quest Vision Technologies): this lens conforms to the geometry of the capsular bag so that the optic moves forward and changes curvature with accommodation to produce up to 4.5 D of power.
NuLens (NuLens): this sulcus fixated lens is composed of a flexible polymer between 2 rigid plates with an opening on the front plate. With increased vitreous pressure, the plates compress, the polymer bulges through the anterior plate aperture, resulting in increased curvature and increased power. The NuLens can achieve 30-50 D of accommodation.
FluidVision IOL (PowerVision): a 1- piece lens with "applied micro fluidic" technology. The dynamic optic is connected to fluid reservoirs at the haptic tips and relies on a hydraulic-induced shape change. Microfluidic pumps reversibly alter the radius of curvature, increasing the lens power by redistributing peripheral fluid centrally, and potentially producing a > 10 D power change.
LiquiLens (Vision Solutions): a dual liquid gravity dependent lens composed of a single optic with 2 immiscible fluids of different refractive index. With downgaze, the liquids change position producing increased power of at least 30 D.
SmartIOL (Medennium): a thermoplastic flexible acrylic gel polymer that can be manufactured to precise optical specifications and customizable into any size, shape, and power. The polymer undergoes a temperature dependent configuration change: it is converted to a thin rod at room temperature, implanted through a microincision, and returns to its original shape (approximately 9.5 mm wide and 3.5 mm thick) and power at body temperature. Potentially, wavefront, toric, and multifocal technology could be imprinted onto the surface of the lens.
Light Adjustable Lens (Calhoun Vision): a photosensitive adjustable foldable 3-piece IOL enabling precise non-invasive post-op adjustment of myopic, hyperopic, and astigmatic errors up to 2 D. The lens is composed of subunits (macromers) embedded in a matrix. Focal UV irradiation from a digital light delivery device (Carl Zeiss Meditec) causes polymerization of macromers, then nonpolymerized macromers diffuse and migrate into the irradiated area causing a power change. Irradiating the lens again locks in the desired configuration. Future possibilities include the potential for multifocal and wavefront adjustments, as well as, readjustments.
Lipshitz Macular Implant (LMI; OptoLight Vision Technology): this special lens magnifies an image 2.5x to improve central vision in patients with severe AMD. It is the next generation of implantable miniature telescope that uses mirrors rather than glass lenses. The original IMT was too large and bulky, required a 10 mm incision, and could only be implanted unilaterally. In comparison, the LMI optic is 6.5 mm and only slightly thicker than a standard IOL, does not affect the peripheral vision, and can be used bilaterally. It contains 2 miniature mirrors (a 2.8 mm posterior doughnut-shaped mirror that reflects light anteiorly onto a 1.4 mm central retina-facing mirror which in turn focuses the light on the retina). In initial trials, patients gained an average of 3.66 lines of VA. A foldable version is in development.
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