The lens is a transparent structure in the front of the eye that focuses an image on the retina, which is the light-sensitive region in the back of the eye.

Light that passes through the lens to the retina is changed into nerve signals that are transmitted to the brain.

A cataract is cloudiness on the lens, which blurs visual images. By age 80, more than 50 percent of adults either have cataracts or have had surgery to remove them. The most common symptoms include:

• Blurred vision

• Faded colors

• Poor night vision, including glares

• Double vision

• Frequent prescription changes for glasses or contact lenses

Cataracts can develop in one or both eyes, and can form after surgery for other eye problems, or as a result of trauma or radiation damage to the eye.

Most cataracts are caused by clumping of proteins that reduce the amount of light that reaches the retina.

If a cataract is small, only part of the lens is affected; the patient may not notice visual changes.

But cataracts tend to grow over time, gradually dulling and blurring vision. In advanced stages of the condition, the lens becomes discolored.

In addition to age, risk factors include diabetes, smoking, alcohol use, and prolonged sunlight exposure.

People can lower their risk for developing cataracts by wearing sunglasses and a hat with a brim to protect the eyes from ultraviolet rays.

Quitting smoking and consuming a diet rich in antioxidant fruits and vegetables may also reduce risk.

Your doctor can detect cataracts with a dilated eye exam. If the condition is mild, new glasses, brighter lighting, and anti-glare sunglasses can help to reduce the symptoms.

If impaired vision interferes with everyday activities, surgery may be required to remove the clouded lens or lenses, which can be replaced with artificial lenses.

Approximately 90 percent of patients who undergo cataract surgery enjoy better vision afterward.