Retina - Common Disorders

Macular Degeneration

Age-related macular degeneration or AMD is the leading cause of vision loss and legal blindness in Americans 65 years or older, affecting more than 10 million people in the United States.  AMD occurs with damage to the macula, which is the central area of the retina responsible for our sharpest vision.  People with AMD may have difficulty with tasks that involve detailed central vision, such as reading, driving, and recognizing faces.  However, AMD does not typically damage peripheral or side vision, which is what we use to get around without bumping into furniture or other objects.

Two Types of Macular Degeneration
Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular).  The dry form is more common than the wet, with about 80-85 percent of AMD patients diagnosed with dry AMD.  The wet form of AMD, however, usually leads to more severe vision loss.

Dry Macular Degeneration

Dry macular degeneration is diagnosed when yellowish spots known as drusen accumulate in the macula region of the retina, damaging the tissue.  The disease typically progresses slowly and some people may maintain good vision for years.  At any time dry AMD can convert to the wet type and cause significant visual symptoms to occur.

 

 

Wet Macular Degeneration

Wet macular degeneration is caused by the growth of new blood vessels (neovascularization) beneath the retina.  These new blood vessels are fragile and leak fluid, protein, lipid and blood.  If this leakage is left untreated, scar tissue forms under the retina leaving blind or blurry spots in the central vision.

 


 

Treatment of Macular Degeneration
Although there are currently no FDA-approved treatments for dry macular degeneration, you can make certain lifestyle and dietary changes to help decrease the risk of disease progression to more advanced stages.  Smoking is strongly linked to macular degeneration, so if you smoke, you should try to stop.  Studies also suggest that a diet high in green, leafy vegetables may be beneficial.  (If you are taking blood thinners, always check with your medical doctor first before making significant dietary changes, as they can decrease the affect of certain blood thinners.)  It is also recommended to wear glasses or sunglasses with UV protection against potentially harmful effects of the sun.  A major National Eye Institute (NEI) study, the Age-Related Eye Disease Study or AREDS, demonstrated that taking high dose formulas of certain nutritional supplements can reduce the risk of early stage AMD progression by 25 percent.   Several different brands of these supplements are currently available, ask your eye care specialist today.  A follow-up study to AREDS, called AREDS II, is currently underway and early results show some benefit to diets high in lutein and zeaxanthin (found in green leafy vegetables) as well as omega-3 fatty acids “good fats”.

There are several FDA-approved treatments for wet AMD, all aimed at stopping the growth of abnormal blood vessels.  These include lasers that directly or indirectly destroy targeted blood vessels or drugs, such as Lucentis, that are injected into the eye to block blood vessel growth stimulators.

An Amsler grid, which consists of straight horizontal and vertical lines, is a useful tool to monitor for any early changes to wet AMD.  You may be asked to check your vision at home daily with this grid.  Someone with macular degeneration may see dark spots or some of the lines may appear wavy, broken or distorted.  New changes should be reported to your eye doctor immediately.

 

Risk Factors for Macular Degeneration
While aging is the most common and significant risk factor, other risk factors are still being studied. Commonly listed risk factors include:

 

  • Family history of AMD (parents, siblings with the disease)
  • Smoking
  • High blood pressure
  • High cholesterol levels
  • Obesity


Early signs of macular degeneration are often detected during routine eye examinations before symptoms occur.  People at risk should be examined with a comprehensive eye exam, including a thorough retinal evaluation.