Your eye works a lot like a camera. Light rays focus through your lens onto the retina , a layer of light-sensitive cells at the back of the eye.
Over time, the lens of our eye can become cloudy, preventing light rays from passing clearly through it onto the retina. The loss of transparency may be so mild that vision is barely affected, or it can be so severe that no shapes or movements are seen-only light and dark. When the lens becomes cloudy enough to obstruct vision to any significant degree, it is called a cataract. Eyeglasses or contact lenses can usually correct slight changes in vision caused by early cataracts, but they cannot sharpen your vision if a more severe cataract is present.
The most common cause of cataract is aging. Other causes include trauma, medications such as prednisone or other steroids, systemic diseases such as diabetes, and prolonged exposure to ultraviolet light. Occasionally, babies are born with a cataract.
Cataracts typically develop slowly and progressively, causing a gradual and painless decrease in vision. Other changes you might experience include: glare, particularly at night or from bright sunlight; frequent changes in your eyeglass prescription; a decrease in color intensity; a yellowing of images; and less commonly, double vision.
As the eye’s natural lens gets harder, farsighted (presbyopic) people, who have difficulty focusing up close, can experience improved near vision and become less dependent on reading glasses. However, nearsighted (myopic) people become more nearsighted, causing a worsening in their distance vision. Some kinds of cataract affect distance vision more than reading vision. Others affect reading vision more than distance vision.
With a routine, outpatient surgical procedure, an eye surgeon can remove the cataract. A synthetic intraocular lens (IOL) is almost always inserted at the time of cataract extraction to replace the focusing power of the natural lens. IOLs can be monofocal (fixed-focus for a preset distance) or multifocal, which allows focused vision at many distances. The time to have cataract surgery is when the cataract is affecting your vision enough to interfere with your normal lifestyle.
Cataract surgery is a very successful operation. One and a half million people have this procedure every year in the United States. As with any surgical procedure, complications can occur during or after surgery, and some are severe enough to limit vision. In the vast majority of cases, however, vision, as well as quality of life, improves.