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A prosthetic adjustable replacement lens, an alternative to cataract surgery, attaches to the eye's focusing muscles to let patients see clearly and focus on near and far images. The lens is said to work well because it mimics the mechanics of a human lens. Patients see clearly after surgery because they regain the ability to focus on images up close and far away.

Conventional cataract surgery uses simple fixed lenses, which restore vision but are not attached to the eye muscles that focus the eye's lens. What's more, the traditional surgery may remove the cloudiness from a patient's vision, but destroy the ability for their eyes to focus on objects up close.

NuLens from Israel-based NuLens Ltd, (nu-lens.com) is a flexible lens mechanism that attaches to the eye's focusing muscles. Company engineers used the FEA program NEiNastran from Noran Engineering Inc, Westminster, Calif., (nenastran.com) in the design stage to determine a plunger force and displacements, and hence, the needed optical muscle or deformed shape for lens sizing. Nonlinear analysis in the FEA program, such as estimating surface contact with large-strain hyperelastic materials, helped measure the needed forces.

In tests, according to the company, an 80 year old patient says he got back the good eyesight he had at 25.