Macular Degeneration

A breakdown of the small central portion of the retina at the back of the eye called the macula.  This part of the eye helps us see fine details and gives us our central (as opposed to peripheral) vision.  The degree of visual loss in macular degeneration ranges from minimal to severe.

Yes.  There are two types: dry and wet. 

• Dry macular degeneration is the most common.  Visual loss is gradual due to progressive thinning of the retinal tissue and can vary from mild to severe. 
  
  
• Wet macular degeneration accounts for about 10% of cases.  In this form of the disease, the visual loss is typically more severe and sudden.  These symptoms are usually due to leakage of blood or fluid from abnormal new blood vessels that have formed in the retina.

While the exact cause of macular degeneration is not known, there are a number of risk factors which have been identified.  These include: age, family history, smoking, deposits in the eye called drusen, diabetes, high blood pressure and cardiovascular disease.  Other important risk factors include: light colored eyes and skin, exposure to ultraviolet light, and a high degree of myopia (nearsightedness).

The symptoms vary depending on the severity of the disease.  They can range from mild blur despite wearing the right prescription lenses to actual distortion (i.e waviness of straight lines).  In more severe cases, there can be a blind spot in the center of the field of vision.

The macula can be evaluated in a number of different ways.  One is direct visualization  with special lenses during a dilated eye exam.  Another is a functional test called an Amsler grid which checks for distortion of straight lines.  Special office based imaging tests including an optical coherence tomography (OCT) and fluorescein angiogram are often used as well.

Unfortunately, there is no cure for macular degeneration. However, there are treatments to help limit progression of the disease and reduce the degree of visual loss. 

More specifically, nutritional supplements including vitamins A, C and E and zinc have been shown to reduce the risk of progression to more severe disease in patients who already have a moderate degree of macular degeneration. However, for patients with no macular degeneration or very mild disease, the data did not show a benefit from the supplements.

For patients with wet macular degeneration, treatments have focused on limiting the effect of abnormal blood vessels that have grown under the retina and the leakage of fluid from these vessels. Treatments in this category include:

• direct application of laser to the macula; photodynamic therapy (PDT), which invloves a special medication injected into the bloodstream which is then activated by laser;
• anti-vascular endothelial growth factor (anti-VEGF) drugs which block the growth factor for the abnormal blood vessels of wet macular degeneration.