These changes in the eye's lens are common as people age, but a simple surgical procedure can help restore clarity.
In a normal eye, the role of the lens is to focus light onto the back of the eye, where nerves perceive images and transmit them to the brain. But when cataracts form, they cloud the lens, obscuring and distorting the light coming into the eye, causing vision to become blurry and poor, according to the American Academy of Ophthalmology (AAO).
Cataracts are generally an age-related eye condition. About 70 percent of people over age 75 have cataracts, according to the AAO. Many people with cataracts also have other eye diseases, such as glaucoma or age-related macular degeneration.
How and Why Cataracts Develop
Age-related eye cataracts occur in two ways:
Clumps of protein form in the lens, causing it to become cloudy. The clouding cuts back the amount of light reaching the retina and it can become so bad that vision blurs. Most age-related cataracts develop in this manner.
The lens grows dull over time, with a yellow or brown color developing in the normally clear lens. Vision takes on a brownish or yellowish tint that can eventually make it difficult to read, perceive fine details, or distinguish some colors.
Researchers have linked certain behaviors to the development of cataracts. These include smoking, heavy drinking, and overexposure to sunlight. According to the AAO, family history of cataracts and obesity both increase risk.
Eye cataracts can also develop due to these factors:
Surgery for other eye problems, like glaucoma
Health conditions such as diabetes or high blood pressure
Eye injuries, though it may take years to develop cataracts after the initial trauma
Exposure to radiation
Using steroids for extended periods
In addition, some babies are born with cataracts, often in both eyes.
Cataract Symptoms and Signs
A cataract starts out small and at first has little effect on your vision. You may notice that your vision is blurred a little, like looking through a cloudy piece of glass or viewing an impressionist painting.
A cataract may make light from the sun or a lamp seem too bright or glaring. Or you may notice when you drive at night that the oncoming headlights cause more glare than before. Colors may not appear as bright as they once did.
The type of cataract you have will affect exactly which symptoms you experience and how soon they will occur. When a nuclear cataract first develops, it can bring about a temporary improvement in your near vision, called "second sight."
Unfortunately, the improved vision is short-lived and will disappear as the cataract worsens. On the other hand, a subcapsular cataract may not produce any symptoms until it's well-developed.
The AAO recommends a baseline eye exam at age 40 followed by exams every two years to check for changes in your vision. After 65, as your risk for cataracts increases, annual eye exams will identify them early.
Diagnosing cataracts involves a thorough eye examination, in which your eye doctor will:
Record your medical history to look for risk factors
Give you an eye chart test to see how strong your vision is
Perform a dilated-eye examination to see if your vision problems are being caused by a cataract or some other eye disease
Test the fluid pressure of your eye, to determine if that might be causing vision problems
How Cataracts Are Treated
Early cases of cataracts may be treated with stronger eyeglasses, brighter lighting in your home, and magnifying lenses. These can improve your eyesight, but do not directly treat cataracts. There currently are no known medications that can treat cataracts, according to the AAO.
If cataracts become so bad that they significantly impair your vision — or even render you legally blind — then you may want to opt for cataract surgery. In this surgery, the cloudy lens is removed from the eye and replaced with an artificial lens. Doctors recommend that you undergo cataract surgery only if the cataract has caused so much vision loss that it interferes with your quality of life — or if it gets in the way of your doctor's ability to treat another eye disease.
Cataract surgery is safe and has a high rate of success, according to the American Optometric Association. Results of an analysis of 13,500 cataract surgeries in the United States, published in the January 2016 issue of Ophthalmology, show that less than 1 percent of the surgeries required a second surgery.
People who undergo cataract surgery can often see well enough to resume their normal activities after a few days of recovery, although their vision will continue to improve in the weeks and months to come. Be sure to follow your doctor’s instructions for medications and self-care after the procedure.