Health Care

Eye cataracts are treated only by being removed. But there is no way to keep the eye’s lens in
By:Patricia Woloch

place and just remove the cataract. In cataract eye surgery, the entire lens must be replaced with an intraocular lens (IOL).

A cataract is an alteration in the nature of the clear lens. The lens sits behind the cornea, pupil and iris, and after light passes through and is bent by the cornea, it passes through the lens. Both the cornea and the lens are curved, transparent structures. They both allow light through and both bend it as it passes through. In this way, the light focuses on the retina and gives clear vision, assuming a 20/20 eye. Of course, many people are nearsighted or farsighted, having a cornea which is too steep or too flat. These conditions are treated with LASIK. However, the lens cannot be treated. If it starts to become clouded by a cataract, eye surgery is required.

Cataract causes
Cataracts are strongly age-related but can also be caused by some systemic diseases, by ultraviolet light, some medications, an eye injury, or by diabetes. The lens is primarily made up of water and proteins. The connection between eye cataracts and aging is not fully understood, but it would seem that aging, with its increasing dryness in the body, can cause the proteins to clump together and form tiny opaque areas which block light. Also, the lens is sealed inside a capsule, a membrane which surrounds it. Old cells dying can become caught inside the membrane, again forming tiny clumps which block the passage of light.

Onset of cataracts is quiet and you may not notice any vision impairment at first. At some point you’ll notice blurring and glare, perhaps less vibrant colors, poor night vision, and even double vision in one eye. Each case of cataracts is unique and yours will progress at its own pace.

At some point your eye doctor will suggest cataract surgery as the best way to restore your vision.

Implanting an IOL
Cataract eye surgery is typically done as an outpatient procedure. An anesthetic is given and your eye doctor will make a tiny incision in the cornea (about three millimeters). Using ultrasound, he will gently disintegrate the lens and remove it. Through that same incision, he will insert a folded IOL and carefully position it correctly.

Accommodation
When the eye’s natural lens is removed, so is the eye’s ability to accommodate. The lens, controlled by tiny muscles, normally changes its curvature depending on whether the eye is focusing on a near object, or a far one. The changes in lens convexity will bend the incoming light rays more or less acutely, maintaining focus on the retina, so that vision is clear at all distances.

There are three IOLs which can restore some of the ability to accommodate:
· ReSTOR® -- which has a series of graduated steps on its surface, for a range of light-bending angles
· ReZoom™ -- which has five optic zones in its structure, for five distance ranges
· Crystalens™ -- which is connected to the same muscles which controlled the natural lens, and is therefore controlled by them also