Presbyopia Correction: Lens Replacement Surgery
Presbyopia (the common age-related condition in which the eye loses its ability to focus on close objects) can be surgically addressed in several different ways, one of which is replacement of the eye’s crystalline lens. In a procedure similar to cataract surgery, the natural lens is removed and replaced by a permanent intraocular lens implant.
Lens replacement surgery (also referred to as clear lens exchange or clear lens extraction) is typically performed in an outpatient surgery center. After the eye is numbed with eye drops, the eye surgeon (ophthalmologist) makes a tiny incision (just large enough to insert a microscopic instrument) at the outer edge of the cornea. The instrument uses ultrasound to gently break the natural lens into small fragments that are easily removed, after which the intraocular lens implant is put into place.
The lens replacement procedure usually is completed in less than an hour, but for most patients it takes from six to twelve weeks for the brain to completely adjust to the news lens. Some patients experience an aftereffect (which typically lessens over time) of seeing halos or glare around lights, but most report that their improved vision far outweighs any visual side effects from the procedure.
Currently there are three types of implantable lenses that address Presbyopia and allow patients to see both near and far without glasses, each with a slightly different design. ReSTOR ® and ReZoom™ lenses are appropriate both for treatment of presbyopia and for use after cataract surgery. The third type, Crystalens™, is also often used for lens replacement after cataract surgery.
ReSTOR Intraocular Lens
Technically known as the AcrySof ® ReSTOR ® Apodized Diffractive Intraocular Lens, ReSTOR is a permanent artificial (soft acrylic) intraocular lens that uses patented technologies for diffraction (the bending of light around corners), refraction (the bending of light as it passes from one medium to another), and apodization (the reduction of fringes that appear around the images of bright points of light). ReSTOR’s special design enables it to accurately focus light on the retina for images at varying distances without any mechanical movement of the lens. Its apodization technology provides an increased range of visual quality with minimal image disturbances. The ReSTOR lens provides good near, intermediate, and distance vision. It is appropriate for adults with presbyopia and is FDA approved for use after cataract surgery. Clinical studies have shown that 80 percent of ReSTOR patients no longer need to wear glasses or contact lenses.
ReZoom Multifocal Intraocular Lens
ReZoom is a permanent artificial (soft acrylic) intraocular lens that uses Balanced View Optics™ technology to enable patients to see clearly at varying distances in a broad range of light conditions. The lens distributes light over five visual zones that are carefully proportioned for different light and focal distances. Each zone then focuses light onto the retina to provide clear vision at close, intermediate, and far distances. ReZoom is appropriate both for adults with presbyopia and for cataract patients. Clinical studies have shown that about 92 percent of ReZoom patients never or rarely need to wear glasses or contact lenses after the procedure.
Crystalens is an artificial intraocular lens formulated from a special type of solid silicone called Biosil™. Originally approved for use as a cataract replacement lens, Crystalens works naturally with the patient’s eye muscles to provide intermediate and near focusing ability. A special feature of the lens is its ability to move (accommodate) to focus on objects at varying distances, which is an improvement over earlier cataract replacement lenses. Now, a number of ophthalmologists are using the Crystalens for clear lens exchange on older patients (when a cataract is not present) as an alternative to LASIK because of its ability to allow patients to focus at both near and far distances.