While the vast majority of those who develop cataracts are senior citizens, this vision-blurring condition is not always related to age.
More than 90 percent of Americans have at least one cataract by age 65, and half of those between 75 and 85 have lost some vision because of the condition, according to the University of Michigan Kellogg Eye Center.
Causes & Risk Factors
Cataracts occur when the eye's lens, the clear layer that focuses light on the retina, becomes cloudy. Because of this, the lens cannot send a sharp image to the retina, the light-sensitive layer at the back of the eye that transmits nerve signals to the brain recording what is seen.
Typically, this clouding develops because the protein that helps comprise the lens begins clumping together on its surface, making it opaque and blurring vision, according to the National Eye Institute (NEI).
However, some babies are born with cataracts, and others develop them because of eye injuries or genetic disorders. Certain risk factors also increase the likelihood of developing cataracts. According to the Mayo Clinic, these include:
- Excessive alcohol use
- Excessive sunlight exposure
- High blood pressure
- Radiation exposure, such as X-rays and cancer radiation therapy
- Previous eye surgery
- Prolonged use of corticosteroid drugs
In the early stages of cataract formation, no symptoms may be present and the condition may progress very slowly. Over time, however, certain signs tend to show up. According to the American Optometric Association (AOA), these include:
- Blurry, cloudy or hazy vision
- Reduced color intensity
- Increased sensitivity to light and glare, especially when driving at night
- Increased difficulty seeing at night
- Seeing "halos" around lights
- Double vision in a single eye
- Frequent prescription changes for eyeglasses or contact lenses
Diagnosis & Testing
Diagnosing cataracts is a relatively simple process, according to the Mayo Clinic, and involves a comprehensive eye exam that may include several different parts:
- Visual acuity test, using an eye chart with progressively smaller letters
- Dilated eye exam, using eye drops to widen the pupils to view the retina and optic nerve with special equipment
- Tonometry, using an instrument to measure internal eye pressure
- Slit-lamp exam, using light and magnification to illuminate the cornea, iris, lens and the space between the iris and cornea
While the use of magnifying devices and brighter lights may stave off cataracts' effects on vision for a period of time, surgery is the only treatment. Surgery is usually considered when cataracts begin to impinge on quality of life, affecting driving, reading or the ability to perform normal activities. Since cataracts don't damage the eye, there is no harm in delaying the procedure, according to the NEI.
Cataract surgery is the most common operation among those over age 65, according to the Kellogg Eye Center, and more than 2 million are done each year on people of all ages. Two types are available:
- Small incision cataract surgery: Also called phacoemulsification, this is the most common type. During the procedure, a tiny probe is inserted into the eye through a small incision on the side of the cornea. This probe releases ultrasound waves that soften and split the lens into pieces, which are suctioned away.
- Extracapsular surgery: A longer incision is made on the side of the cornea and the cloudy core of the lens is removed in one piece. The rest is suctioned away.
In both types of procedures, the removed lens is replaced with an artificial one made of plastic, according to the NEI. It becomes a permanent part of the eye and cannot be felt or seen.
As with all surgery, cataract removal has risks, including infection, bleeding and retinal detachment, according to the Mayo Clinic.