Cataracts

A cataract is a clouding of the normally clear lens of your eye. Looking through a cloudy lens is like trying to see through a frosty or fogged-up window. Clouded vision can make it more difficult to read, drive a car — especially at night — or see the expression on a friend’s face. Cataracts commonly affect distance vision and cause problems with glare. They generally don’t cause surface irritation or pain.
Clouding of the lens is a normal part of getting older.
Most cataracts develop slowly and don’t disturb your eyesight early on. But as the clouding progresses, the cataract eventually interferes with your vision.
In the early stages, stronger lighting and eyeglasses can help you deal with the vision problems. But at some point, if impaired vision jeopardizes your normal lifestyle, you might need surgery. Fortunately, cataract removal is one of the safest, most effective and most common surgical procedures.

How can cataracts affect my vision?

Age-related cataracts can affect your vision in two ways:

1. Clumps of protein reduce the sharpness of the image reaching the retina.
The lens consists mostly of water and protein. When the protein clumps up, it clouds the lens and reduces the light that reaches the retina. The clouding may become severe enough to cause blurred vision. Most age-related cataracts develop from protein clumpings.
When a cataract is small, the cloudiness affects only a small part of the lens. You may not notice any changes in your vision. Cataracts tend to “grow” slowly, so vision gets worse gradually. Over time, the cloudy area in the lens may get larger, and the cataract may increase in size. Seeing may become more difficult. Your vision may get duller or blurrier.

2. The clear lens slowly changes to a yellowish/brownish color, adding a brownish tint to vision.
As the clear lens slowly colors with age, your vision gradually may acquire a brownish shade. At first, the amount of tinting may be small and may not cause a vision problem. Over time, increased tinting may make it more difficult to read and perform other routine activities. This gradual change in the amount of tinting does not affect the sharpness of the image transmitted to the retina.
If you have advanced lens discoloration, you may not be able to identify blues and purples. You may be wearing what you believe to be a pair of black socks, only to find out from friends that you are wearing purple socks.

Causes and Risk Factors

Causes

The lens lies behind the iris and the pupil. It works much like a camera lens. It focuses light onto the retina at the back of the eye, where an image is recorded. The lens also adjusts the eye’s focus, letting us see things clearly both up close and far away. The lens is made of mostly water and protein. The protein is arranged in a precise way that keeps the lens clear and lets light pass through it.
But as we age, some of the protein may clump together and start to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it harder to see.
Researchers suspect that there are several causes of cataract, such as smoking and diabetes. Or, it may be that the protein in the lens just changes from the wear and tear it takes over the years.

Risk factors

Everyone is at risk of developing cataracts simply because age is the single greatest risk factor.
Other factors that increase your risk of cataracts include:

  • Diabetes
  • Family history of cataracts
  • Previous eye injury or inflammation
  • Previous eye surgery
  • Prolonged use of corticosteroids
  • Excessive exposure to sunlight
  • Exposure to ionizing radiation
  • Smoking

Screening and diagnosis

The only way to know for sure if you have a cataract is to have an eye examination that includes several tests:

  1. Visual acuity test. Acuity refers to the sharpness of your vision or how clearly you see an object. In this test, your eye doctor checks to see how well you read letters from across the room. Your eyes are tested one at a time, while the other eye is covered. Using the chart with progressively smaller letters from top to bottom, your eye doctor determines if you have 20/20 vision or less acute vision.
  2. Slit-lamp examination. A slit lamp allows your eye doctor to see the structures at the front of your eye under magnification. The microscope is called a slit lamp because it uses an intense line of light — a slit — to illuminate your cornea, iris, lens and the space between your iris and cornea. The slit allows your doctor to view these structures in small sections, which makes it easier to detect any small abnormalities.
  3. Retinal examination. In this procedure, your eye doctor puts dilating drops in your eyes to open your pupils wide and provide a bigger window to the back of your eyes. Using a slit lamp or a special device called an ophthalmoscope, he or she can examine your lens for signs of a cataract and, if needed, determine how dense the clouding is. Your eye doctor will also check for glaucoma and, if you have blurred vision or discomfort, check for other problems involving the retina and the optic nerve. Dilating drops usually keep your pupils open for a few hours before their effect gradually wears off. Until then, you’ll probably have difficulty focusing on close objects, while your distance vision is generally less affected. With your pupils open this wide, you may want sunglasses for your trip home, especially if it’s a bright day. Also, it may be safer to let someone else do the driving.

Nutrition

Several research studies show that the antioxidant properties of vitamins C and E may protect against the development and progression of cataracts. Early evidence also suggests that the carotenoids lutein (pronounced loo-teen) and zeaxanthin (pronounced zee-uh-zan-thin), which are also antioxidants, may also be protective against cataracts.

Antioxidant Vitamins

Some recent studies compared diet and supplement intake of the antioxidant vitamins C and E with the development of cataracts. Many of these studies have shown that these antioxidants may decrease the development or progression of this disease. Some of the results are listed below:

  • The Nutrition and Vision Project found that higher intakes of vitamin C led to a reduced risk for cortical and nuclear cataracts. Results also showed that people who used vitamin C and E supplements for more than ten years had decreased progression of nuclear cataracts.
  • A recent analysis of results from a national dietary study (Second National Health and Nutrition Examination Survey) found that higher levels of vitamin C in the diet were associated with lower risk of cataracts.
  • In the Nurses’ Health Study, the need for cataract surgery was lower among women who used vitamin C supplements for ten years or longer.
  • The Roche European American Cataract Trial found that an antioxidant supplement with vitamins C and E and beta-carotene lead to a small decrease in the progression of cataracts in less than 3 years.
  • In the Longitudinal Study of Cataract, vitamin E supplement use for at least a year was associated with a reduced risk of nuclear cataracts becoming more severe.
  • The five year follow-up to the Beaver Dam Eye Study showed a reduced risk for nuclear and cortical cataracts among people using multivitamins or any supplement containing vitamins C and E.

Lutein and Zeaxanthin

Lutein and zeaxanthin are promising nutrients in the fight against cataracts. Lutein and zeaxanthin are the only carotenoids found in the lens. Several recent studies have examined these two nutrients and their relationship to reducing the risk of developing cataracts:

  • The Nurses’ Health Study found that high amounts of lutein+zeaxanthin were associated with a reduced need for cataract surgery. On average, people had intakes around 6 milligrams (mg) of lutein+zeaxanthin each day.
  • The Health Professional’s Follow-Up Study also found that eating foods with high amounts of lutein+zeaxanthin (6.9 mg per day) were correlated with a reduced need for cataract surgery.
  • The five-year follow-up to the Beaver Dam Eye Study showed that people with the highest intakes of lutein+zeaxanthin had a significantly lower risk for developing new cataracts than those with the lowest intakes.
  • A recent study in England found that people with the highest amount of lutein in their blood, resulting from regular consumption of good food sources of lutein, had the lowest risk for posterior subcapsular cataracts.

Treatment

The symptoms of early cataract may be improved with new eyeglasses, brighter lighting, anti-glare sunglasses, or magnifying lenses. If these measures do not help, surgery is the only effective treatment. Surgery involves removing the cloudy lens and replacing it with an artificial lens.
A cataract needs to be removed only when vision loss interferes with your everyday activities, such as driving, reading, or watching TV. You and your eye care professional can make this decision together. Once you understand the benefits and risks of surgery, you can make an informed decision about whether cataract surgery is right for you. In most cases, delaying cataract surgery will not cause long-term damage to your eye or make the surgery more difficult. You do not have to rush into surgery.
Sometimes a cataract should be removed even if it does not cause problems with your vision. For example, a cataract should be removed if it prevents examination or treatment of another eye problem, such as age-related macular degeneration or diabetic retinopathy. If your eye care professional finds a cataract, you may not need cataract surgery for several years. In fact, you might never need cataract surgery. By having your vision tested regularly, you and your eye care professional can discuss if and when you might need treatment.
If you choose surgery, your eye care professional may refer you to a specialist to remove the cataract.
If you have cataracts in both eyes that require surgery, the surgery will be performed on each eye at separate times, usually four to eight weeks apart.

Different types of cataract surgery

There are two types of cataract surgery.

  1. Phacoemulsification, or phaco. A small incision is made on the side of the cornea, the clear, dome-shaped surface that covers the front of the eye. Your doctor inserts a tiny probe into the eye. This device emits ultrasound waves that soften and break up the lens so that it can be removed by suction. Most cataract surgery today is done by phacoemulsification, also called “small incision cataract surgery.”
  2. Extracapsular surgery. Your doctor makes a longer incision on the side of the cornea and removes the cloudy core of the lens in one piece. The rest of the lens is removed by suction.

After the natural lens has been removed, it often is replaced by an artificial lens, called an intraocular lens (IOL). An IOL is a clear, plastic lens that requires no care and becomes a permanent part of your eye. Light is focused clearly by the IOL onto the retina, improving your vision. You will not feel or see the new lens.
Some people cannot have an IOL. They may have another eye disease or have problems during surgery. For these patients, a soft contact lens, or glasses that provide high magnification, may be suggested.

What are the risks of cataract surgery?

As with any surgery, cataract surgery poses risks, such as infection and bleeding. Before cataract surgery, your doctor may ask you to temporarily stop taking certain medications that increase the risk of bleeding during surgery. After surgery, you must keep your eye clean, wash your hands before touching your eye, and use the prescribed medications to help minimize the risk of infection. Serious infection can result in loss of vision.
Cataract surgery slightly increases your risk of retinal detachment. Other eye disorders, such as high myopia (nearsightedness), can further increase your risk of retinal detachment after cataract surgery. One sign of a retinal detachment is a sudden increase in flashes or floaters. Floaters are little “cobwebs” or specks that seem to float about in your field of vision. If you notice a sudden increase in floaters or flashes, see an eye care professional immediately. A retinal detachment is a medical emergency. If necessary, go to an emergency service or hospital. Your eye must be examined by an eye surgeon as soon as possible. A retinal detachment causes no pain. Early treatment for retinal detachment often can prevent permanent loss of vision. The sooner you get treatment, the more likely you will regain good vision. Even if you are treated promptly, some vision may be lost.

Sources: Mayo Clinic, AOA

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