The above example demonstrates how a cataract clouds the clear lens making vision less defined.
As one ages, chemical changes occur in the lens that make it less transparent. The loss of transparency may be so mild that vision is hardly affected or so severe that no shapes or movements can be seen, only light and dark. When the lens gets cloudy enough to obstruct vision to any significant degree, it is called a cataract.
The eye works much like a camera. Light rays focus through the lens onto the retina. The retina, which is similar to film, allows the image to be"seen" by the brain. Over time, the lens can become cloudy and prevent light rays from passing clearly through it. This cloudy lens is called a cataract.
The most common cause of a cataract is aging, and it is estimated that 20.5 million Americans over the age of 40 are affected. Other causes include:
- Certain medications such as steroids
- Systemic diseases, including diabetes
- History of smoking
- Prolonged exposure to ultraviolet light
- Congenital cataract
Cataracts can occur in one or both eyes, and glasses or contact lenses will not sharpen vision if a cataract is present. Once formed, the only cure for a cataract is surgical removal. Patients may reduce the risk for developing a cataract by limiting the amount of ultraviolet light exposure and wearing a wide-brim hat and sunglasses.
The typical symptom of cataract formation is a slow, progressive and painless decrease in vision. Other changes include:
- Cloudy or blurred vision
- Glare, particularly at night
- Frequent eyeglass prescription changes
- Decrease in color intensity
- Yellowing of images
- Double vision
Early symptoms of cataracts can often be managed, however, when vision loss from a cataract interferes with a patient's lifestyle, surgical removal of the cataract is the only treatment.