LASIK (Laser assisted in-situ keratomileusis) is a refractive surgical procedure that results in rapid recovery of vision and has the capability to benefit patients with nearsightedness, farsightedness, and astigmatism by reducing dependence on eyeglasses and contact lenses. Millions of people worldwide have already undergone this exciting and marvelous procedure. Nearly a million people in the U.S. underwent LASIK in 1999 and approximately 1.3 million underwent the procedure in 2000. The great majority of individuals who wear glasses or contacts may now benefit from LASIK. Candidates must be at least 18 years of age.

The Crystalens is designed to move within the eye, to provide focusing at all distances. Animation courtesy of eyeonics.

LASIK is a procedure in which the eye surgeon creates a thin surface flap of the cornea using a microkeratome to expose underlying tissues (stromal bed). It is within the deeper layers of the cornea that the surgeon then applies the Excimer laser beam to create the refractive ablation. This reshapes the cornea using the extraordinary precision of the Excimer laser.

The laser is programmed prior to each procedure for the ablative "cut" based on the patient's pre-operative refractive error (nearsightedness, farsightedness, and astigmatism). Once the laser ablation is completed, the surgeon gently replaces the corneal surface flap to restore surface integrity of the eye. It's as if the refraction is "ground in" to the middle layers of the cornea! The results are often dramatic and very rapid, with most patients seeing well enough to drive a car without correction the very next day. However, the best post-operative visual acuity may not be obtained until 2 to 3 weeks, or in some cases, even a few months, after the procedure.

LASIK nearly always results in improved vision without correction. However, LASIK is an imperfect procedure, and does not always result in 20/20, or even 20/40 visual acuity. The large majority of patients can expect to see well without glasses or contact lenses, however, those patients with the highest degrees of refractive error (above ­7.0 D myopia and 3 to 4 D astigmatism) should reduce their expectations for the procedure.

multi-focal IOLs use a different strategy to achieve good distance and near vision without glasses. These lenses have highly specialized optical properties that can divide light to bring it into focus at more than one point at the same time. This allows the eye to see both near and far, usually without glasses. Excellent results for distance and near vision have been achieved by both of the FDA approved lenses of this type.

The ReZoom™ multi-focal IOL has several zones of optical power that are designed to provide good vision at varying distances, under varying lighting conditions. In a clinical study, 92 percent of ReZoom™ IOL patients reported never or only occasionally having to wear glasses. Another multi-focal IOL is the ReSTOR™. This IOL uses a patented diffractive optical design to divide light into two focal zones so that near and distance objects can both be seen without glasses. An impressive 80% of patients from the ReSTOR FDA trial reported that they never wore glasses after the procedure(3).

multi-focal IOLs have a slightly greater tendency to cause night vision complaints than other IOLs, so those who drive a great deal at night may wish to consider a different IOL. The vast majority of patients with these IOLs are not bothered by night vision complaints, however.

Traditional IOLs are monofocal, meaning they offer vision at one distance only (far, intermediate, or near). They are definitely an improvement over the cataractous lens that is replaced during surgery, which provides only cloudy, blurred vision at any distance. But traditional IOLs mean that you must wear eyeglasses or contact lenses in order to read, use a computer, or view objects in the middle distance, especially if you are already experiencing presbyopia before cataract surgery.

Restor

The new multi-focal and accommodating IOLs offer the possibility of seeing well at more than one distance, without glasses or contacts. Here are a few examples (note: this is not a complete list): Alcon AcrySof ReStor

AcrySof ReSTOR uses apodized diffractive technology — a design that responds to how wide or small the eye's pupil might be — to provide near, intermediate, and distance vision. Clinical studies used to support the March 2005 FDA approval showed that 80 percent of people who received the lens didn't use glasses for any activities after their cataract surgery; 84 percent who received the lens in both eyes had distance vision of 20/25 or better, with near vision of 20/32 or better.

ReZoom

ReZoom is a multi-focal refractive IOL that distributes light over five optical zones to provide near, intermediate, and distance vision. Its manufacturer, Advanced Medical Optics, brought the first multi-focal IOL to the U.S. market in the late 1990s; the ReZoom is its second-generation multi-focal and was FDA-approved in March 2005. In a European study of 215 patients, 93 percent of ReZoom recipients reported never or only occasionally needing glasses.

Crystalens gained FDA approval in late 2003. It was designed to restore the eye's accommodation ability, which is gradually reduced as presbyopia progresses. "Accommodation" is the ability of the eyes to change focus from near to far, far to near, and all distances in between. With presbyopia, which usually begins at around age 40, the eye muscle that accomplishes this accommodation — the ciliary muscle — has more difficulty in doing its job, because the eye's lens is becoming less flexible. The ciliary muscle contracts in its effort to move the lens forward, bending it slightly for close up focusing; but the lens resists because it is not as flexible as it was when the eye was younger.

The Crystalens is designed to move within the eye, to provide focusing at all distances. (Animation courtesy of eyeonics.) eyeonics Crystalens

Since Crystalens has hinges on both sides of the IOL, it can be moved more easily by the ciliary muscle, allowing the eye to focus more naturally at a greater range of distances than traditional IOLs. So far, Crystalens is the only accommodating IOL that has been approved by the FDA, though others are in development.

It's important to note that you can't be 100 percent certain of seeing well without eyeglasses or contact lenses after cataract surgery, even if your eyes have received multi-focal or accommodating IOLs. Some of the factors that can decrease satisfaction with these IOLs include pre-existing astigmatism, incorrect positioning of the IOLs in the eye, and nighttime halos that some patients have experienced.

But even with these risks, these new IOLs do provide the probability of good vision without total dependence on eyeglasses or contacts. You may even achieve good vision without using these aids at all.