Cataracts Treatment Options

by Food and Drug Administration (FDA)

(Page 2 of 2)

Treatment Options

During the diagnostic examination, an ophthalmologist will carefully measure the shape, size and general health of the eye to determine whether a lens implant will be effective. In the relatively small number of cases where it won't be, eyeglasses or contact lenses will improve vision after traditional cataract surgery. Glasses, while used for years, have drawbacks. Their extreme thickness makes them unattractive and heavy. Magnification and distortion of the visual image causes objects to appear closer and 25 percent larger than they are. Peripheral vision may be reduced. Contact lenses provide fairly good vision, but many elderly people have trouble inserting, removing and cleaning them.

An implanted IOL is usually the best replacement. Because the implant is placed in or near the original position of the removed natural lens, vision is restored with good peripheral vision and depth perception yet with minimal magnification and distortion.

Getting an IOL

IOLs remain permanently in place, require no maintenance or handling, and are neither felt by the patient nor noticed by others. Eyeglasses with thin lenses for near or distant viewing may still be required, but thick glasses are not necessary. A doctor can determine the appropriate implant prescription with an ultrasound device that measures eye length and corneal curvature. These measurements are combined by computer to calculate the lens power required.

The standard surgical procedure, which ranges in cost from $3,000 to $5,000, is performed in a hospital or doctor's office. Peering through an operating microscope, the surgeon makes a minute, curved incision in the cornea — the surface of the eye. Then the clouded lens is cut loose with a thin needle and suctioned out, leaving intact the rear wall of the transparent capsule that encloses the lens.

The surgeon enlarges the original incision, and the new lens — a clear hard plastic disc — is then slipped in behind the iris and up against the back wall of the capsule. Two tiny "c" shaped arms attached to the lens eventually become scarred into the side of the eye and hold the lens firmly in place. The incision is closed with 7 to 10 nearly invisible stitches of fine nylon or silk.

In a newer method, an ultrasonic probe enters the cut in the cornea and high-speed vibrations break the lens into microscopic flecks that are then removed by suction. A folded flexible plastic lens one-quarter of an inch in diameter can be inserted through the cut with a scissors-like device called an injector and positioned behind the pupil against the capsule wall. Once in place, the injector is removed and the lens opens.

The flexible lens is one of two advances already on the market in half a dozen European countries. This softer lens, designed to allow a smaller incision and thus less tissue damage than implantation of the standard hard lens, is now undergoing clinical trials in the United States and is expected to be available here in late 1990.

Some manufacturers are also developing bifocal IOLs, which may eliminate the need in some patients for prescription glasses after surgery. The bifocal IOLs could be on the market in the United States in 1991.

The procedure to remove the natural lens and replace it with a synthetic one is done under a general or local anesthesia with injections made in muscles around the eye. Recovery takes several hours in the hospital; in a few cases, it may require an overnight stay. The patient wears a metal shield over the eye at night; wrap-around sunglasses are recommended during the day.

Within a few days of the operation, most people are back at work. In several office visits during the first six to eight weeks after surgery, the doctor will check for infections or other complications and fit the patient for reading glasses. Vision is significantly improved in 95 to 98 percent of cases.

However, results of the operation aren't always worry free. After the IOL implantation, a clouding of the lens capsule, known as a "secondary cataract," occurs in roughly 40 percent of cases. To restore vision, a pulsed yttrium, aluminum, garnet (YAG) laser is used to produce a hole non-thermally, by "optical breakdown," in the capsule to allow the normal passage of light rays back to the retina. This painless procedure takes a few minutes; improvement usually is immediate. Other problems that may occur in a small percentage of patients include swelling of the cornea, glaucoma, and swelling of the retina, which distorts vision.

Overall, though, IOLs "have turned out to be much better than anyone ever expected," says FDA's Brogdon.

At a time when more older Americans than ever before are looking forward to years of active life ahead of them, IOLs offer hope and a better life.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.