A cataract is a clouding of the eye’s lens, which blocks or changes the passage of light into the eye. The lens of the eye is located behind the pupil and the colored iris, and is normally transparent. The lens helps to focus images onto the retina – which transmits the images to the brain.
Your vision may become blurry or dim because the cataract stops light from properly passing through to your retina.
The exact cause of a cataract is unknown. Most often, a cataract is part of getting older. As you age, you are at greater risk of developing a cataract. There are also several possible risk factors for cataracts, such as:
• Intense heat or long-term exposure to UV rays from the sun
• Certain diseases, such as diabetes
• Inflammation in the eye
• Hereditary influences
• Events before birth, such as German measles in the mother
• Long-term steroid use
• Eye injuries
• Eye diseases
Generally, a cataract does not cause pain, redness or tears. The following problems may indicate that you have a cataract:
• You have blurred vision, double vision, ghost images, or the sense of a “film” over your eyes.
• Lights seem too dim for reading or close-up work, or you are “dazzled” by strong light.
• You change eyeglass prescriptions often and the change does not seem to help your vision.
• You may also be able to see the cataract in your eye. It may look like a milky or yellowish spot in your pupil.
Cataracts are probably caused by changes related to aging. Throughout our lives, our bodies replace old cells with new ones. As we grow older, the old cells in our eye’s lens build up and block light as it tries to pass through. The end result is cloudy vision.
Besides getting older, other factors may cause cataracts to form. Eye infections, some medicines (such as steroids), injuries or exposure to intense heat or radiation may cause cataracts. Too much exposure to non-visible sunlight (called UV or ultraviolet light) and various diseases, such as diabetes or metabolic disorders, may also contribute to cataracts forming.
Age-related – 95% of cataracts are age-related, usually after age 40.
Cataracts usually form in both eyes, but not at the same rate. They can develop slowly or quickly, or progress to a certain point, then not get any worse. As a result, you may not notice large changes in your sight right away.