Replacing the Lens
Once the lens is surgically removed, it's usually replaced with an IOL (intraocular lens). Less frequently, glasses or contacts may be used.
Intraocular lens implants
In most people, once the first phase of the surgery is over and the cataract has been removed, an IOL will be put into place. The quarter-inch plastic lens implant is typically inserted into the lens capsule behind the iris (posterior chamber IOL). However, when the lens capsule is absent, a different kind of IOL may be inserted in front of the iris (anterior chamber IOL). IOLs have been in wide use since 1977, are considered safe, and represent the current standard of care. More than 100 brands of IOLs are available, and more are being developed.
The most commonly used type of implant is the monofocal (single-focus) lens. Unlike the natural lens of the eye, a monofocal IOL cannot alter its shape to bring objects at different distances into focus. As a result, the surgeon generally selects a lens that will provide good distance vision, and the person wears reading glasses for near vision. Alternatively, the surgeon can correct one eye for distance and the other for near vision (a type of correction called monovision).
Another option is an IOL that provides a range of vision. These implants are called presbyopia-correcting IOLs. Currently approved implants in this category are multifocal IOLs (ReZoom, ReSTOR, and Tecnis), which provide both distance and near vision by having rings in the implant that focus light at different points. Another IOL, the Crystalens, is not a multifocal lens; however, it offers a range of vision by flexing and arcing in the eye.
An eye surgeon who is experienced in the use of these lenses can discuss the pros and cons of each. Although these lenses reduce the need for eyeglasses (about 90 percent of people no longer need glasses on a routine basis), some people may still need them for specific tasks.
Once inserted, lens implants require no care. As with any device, however, complications can occur. The most common is glare or reduced vision when the IOL is not aligned with the pupil.
In general, new eyeglasses are not prescribed until about three weeks after cataract surgery, because the prescription changes as the eye heals. Nevertheless, if the eye is otherwise normal, individuals with IOLs often have functional vision as early as the first day after surgery.
Cataract glasses are an alternative to IOLs after surgical removal of the lens but are seldom used because they are heavy and awkward. The glasses magnify objects by approximately 25 percent, causing objects to appear closer than they actually area disorienting sensation.
Because of the thickness and curvature of the lenses, cataract glasses magnify objects unequally and so have a distorting effect as well. In addition, they tend to limit peripheral vision. When used, cataract glasses are typically prescribed four to eight weeks after surgery.
Like cataract glasses, contact lenses are not routinely used after cataract lens removal surgery. The lenses provide almost normal vision; however, people often have difficulty handling, removing, and cleaning them. Frequent handling of contact lenses may also increase the risk of eye infection. Because the patient must be able to see when the contacts are not in place, a pair of cataract glasses also is necessary. Like the glasses, contact lenses are prescribed four to eight weeks after surgery.