Medical Health Encyclopedia

It takes about 2 to 4 weeks to completely restore vision.

Replacement Lenses and Glasses

With the clouded lens removed, the eye cannot focus a sharp image on the retina. A replacement lens or eyeglass are therefore needed:

Intraocular Lenses (IOL). In about 90% of cataract operations, an artificial lens, known as an intraocular lens (IOLs), is inserted. Until recently, IOLs used to employ a pair of little spring-loaded loops to hold the lens in place. Most IOLs are now foldable, which makes insertion easier. In fact, a prefolded lens is now available that unrolls to fit the eye as body temperature warms it.

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Although all the lens materials are presumably chemically inert, there are some reports of specific problems, notably a risk for causing a reaction that leads to the development of secondary cataracts, a condition called posterior capsular opacification. IOLs are usually made of one of the following materials:

• Acrylic: The majority of IOLs are made from acrylic, which allows a controlled unfolding of the lens. Evidence now suggests that this material provides a better visual outcome and fewer complications than other standard IOLs.
• Polymethylmethacrylate (PMMA): Has the longest safety record. A PMMA IOL coated with heparin, a blood thinner, helps protect against the development of a secondary cataract after surgery.
• Silicone: Can be inserted through a smaller incision than other materials. It has the highest rates of secondary cataracts. Newer forms of silicon IOLs may pose a lower risk.
• Crystalens: The FDA approved the Crystalens IOL in November 2003. It is made from a proprietary form of silicone called Biosil. The Crystalens uses "hinges" that allow the lens to move, mimicking the eye's natural ability to focus automatically and seamlessly at all distances. Studies have shown that when used along with standard cataract removal methods, the Crystalens restored a patient's full range of functional vision, from distance to reading vision without total dependence on glasses or contact lenses.
• Tecnis Z9000: The Tecnis foldable IOL was specifically designed to improve functional vision of cataract surgery patients. Tecnis has a patented surface which reduces light scattering (spherical aberration) of the cornea, which can negatively affect vision. In April 2004, The FDA approved new labeling claims for Tecnis, allowing the product's manufacturer to market the lens as a way to improve the driving safety for millions of senior cataract patients. In clinical trials, simulated night driving and visual acuity (i.e., 20/20, 20/40, etc.) results were significantly better in eyes implanted with the Tecnis IOL. In addition, spherical aberrations were significantly less when compared to the traditional lens with the spherical optic.
• AcrySof Natural: Approved in 2003, the yellow-tinted Acrysof Natural IOL was the first foldable lens to filter ultraviolet and blue-light. Eliminating both UV and portions of the high-energy blue light help prevent retinal damage. This lens also conforms to the natural shape of the human lens capsule so it remains centered over the eye.
• AcrySof ReSTOR: The AcrySof ReSTOR IOL is approved in the U.S. for patients with and without presbyopia (farsightedness). The lens enhances vision at near, intermediate, and distant ranges. In clinical trials, 80% of patients who received the lens did not require glasses after cataract surgery. The FDA approved the AcrySof ReSTOR in March 2005.