Eye Conditions of the Elderly - Cataracts
A cataract is a cloudy or opaque area in the normally transparent lens of the eye.
As the opacity thickens, it prevents light rays from passing through the lens and focusing on the retina, the light sensitive tissue lining the back of the eye. Early lens changes or opacities may not disturb vision. But as the lens continues to change, several specific symptoms including blurred vision; sensitivity to light and glare; increased nearsightedness; or distorted images in either eye, may develop.
The lens is located behind the iris, the colored portion of the eye, and the pupil, the dark center of the eye. Tiny ligaments, called zonules, support the lens capsule within the eye.The lens has three parts, the capsule, the nucleus, and the cortex. The outer membrane, or capsule, surrounds the cortex which in turn surrounds the center or nucleus of the lens. If you imagine the lens as a piece of fruit, the capsule is the skin, the cortex is the fleshy fruit, and the nucleus is the pit.
Types of Cataracts
There are three types of cataracts. Each is described by its location on the lens.
The most common type of cataract and the one associated with aging is called a nuclear cataract.
A nuclear cataract occurs in the center of the lens. Common symptoms include blurring or dimming of your vision, glare and visual distortion. A nuclear cataract can induce myopia, or nearsightedness, a temporary improvement in your reading vision sometimes referred to as "second sight." Unfortunately "second sight" disappears as the cataract gets worse.
The cortical cataract begins as wedge-shaped spokes in the cortex of the lens.
The spokes extend from the outside of the lens to the center. When the spokes reach the center, they interfere with the transmission of light and cause glare and loss of contrast. Many people with diabetes develop this type of cataract. Although a cortical cataract usually develops slowly, it may impair both distance and near vision so significantly that surgery may be suggested at a relatively early stage.
A subcapsular cataract develops slowly and starts as a small opacity under the capsule, usually at the back of the lens. Significant visual symptoms may not appear until the cataract is well developed. Typical symptoms are glare and blur. A subcapsular cataract is often found in people with diabetes or high myopia, adults with retinitis pigmentosa, and in people taking steroids.
If you have a cataract, you may be experiencing any of these symptoms:
- Painless blurring or dimming of your vision
- Sensitivity to light and glare, especially in bright sunlight or while driving at night
- Increased nearsightedness, requiring frequent changes in your eyeglass prescription
- Distortion or ghost images in either eye
Can Cataracts Be Prevented?
No one understands exactly why the eye's lens changes as we age. Researchers, looking for preventive measures, are gradually identifying factors that may initiate or facilitate the development of cataracts.
Recent studies show people living in high altitudes or those who spend a lot of time in the sun develop cataracts earlier than others. Ophthalmologists now recommend wearing sunglasses and a wide-brimmed hat to lessen the eyes' exposure to UV light.
Other studies suggest people with diabetes are at risk for developing a cataract, as are users of steroids, diuretics, and major tranquilizers. But more studies are needed to differentiate the effect of the disease from the effect of the drugs themselves.
The location and the density of the cataract have a lot to do with what symptoms you experience and how soon you experience them. When symptoms begin to appear, new glasses, strong bifocals, magnification, appropriate lighting, or other visual aids may improve vision for a while.
You should consider surgery when poor vision threatens your enjoyment of life or your ability to maintain an independent lifestyle. Occasionally, a cataract obstructs the view of another eye problem that needs treatment. When this occurs, the cataract should be removed even if symptoms are not significant. But in most cases, there is no reason to have a cataract removed until your own visual requirements demand it. When you decide it's time, discuss your decision thoroughly with the ophthalmologist who will be performing the surgery.
Remember, cataract surgery is not only the most frequently performed surgery in the United States, it is also one of the most consistently successful. Over 90% of the people who have cataract surgery regain useful vision, somewhere between 20/40 and 20/20.
If you have additional questions or would like more information, please contact the expert staff at Eye Care for the Adirondacks.