AMD

AMD, ARMD is condition that can occur in individuals above the age of 50 years. It tends to occur bilaterally but can affect only one eye initially. It is the leading cause of irreversible blindness in the industrialized world and in Asia; it is fast becoming a major problem.

One of the reasons for this is due to the lack of understanding about the condition amongst the public. Only 2% of adults know that ARMD is the leading cause of vision loss in people over 50 years of age and almost 75% of people do not know of a treatment for ARMD. Although it is a cause of irreversible blindness, early detection and intervention will be able to arrest its development.

ARMD occurs when the central portion of the retina, called macula, is damage (pic 1). The macula is the part of the retina that allows us to see fine details. If it is damaged, the central vision would blur or darken. Untreated, simple essential tasks like reading and driving will be severely affected.

There are two types of ARMD;

The Dry type occurs in about 90% of patients with ARMD. There is a gradual thinning of the macula area with deposition of yellowish materials called Drusens (pic 2). Generally vision is well maintained in the Dry type but regular ophthalmological assessment is crucial since about 15-20% will progress to the Wet type.

The Wet type is caused by leaking abnormal blood vessels (choroidal neovascular membranes) located beneath the macula area. Although it constitutes only about 10% of ARMD, it is the cause of more than 90% of blindness associated with ARMD. Untreated this leakage will lead to the formation of scar tissues beneath the macula. This will lead to irreversible loss of sight. (pic 3).

SYMPTOMS

The symptoms associated with ARMD are mainly due to the Wet type and these include:

  • Loss of the ability to see objects clearly
  • Straight lines appear to be wavy and distorted
  • Loss of clear and correct color vision
  • Print looks washed out while reading
  • A dark area blocks the vision in the center of your eye

CAUSES AND RISK FACTORS

The greatest risk factor for ARMD is age. Studies show that people over age 60 are clearly at greater risk than other age groups. For instance, a large study found that people in middle-age have about a 2 percent risk of getting ARMD, but this risk increased to nearly 30 percent in those over age 75.

Other risk factors include:

  • Smoking. Smoking may increase the risk of ARMD.
  • Obesity. Research studies suggest a link between obesity and the progression of early and intermediate stage ARMD to advanced ARMD.
  • Race. Whites are much more likely to lose vision from ARMD than African Americans.
  • Family history. Those with immediate family members who have ARMD are at a higher risk of developing the disease.
  • Gender. Women appear to be at greater risk than men.

TREATMENT

There is as yet no outright cure for macular degeneration, but some treatments may delay its progression or even improve vision. These include:

Thermal Laser Photocoagulation

The benefit of this treatment is that it can prevent further degeneration of the macula. However, the laser treatment can damage healthy macula cells meaning that you might lose a little sight to save a lot.

Photodynamic Therapy (PDT)

PDT utilizes a light-sensitive dye which is injected into the bloodstream and transported to macula which will highlight the abnormal blood vessels. A low energy or ‘cold’ laser beam is then applied to induce a chemical reaction and destroy the leaking blood vessels without damaging the surrounding healthy tissue

Anti Vascular Endothelial Growth Factor (VEGF)

The most recent development in the treatment of ARMD is the availability of anti VEGF’s. These drugs inhibit the role of VEGF in the formation of new vessels. It is injected directly into the eye with a small needle and is done in the clinic under topical anesthesia. It is however, necessary to have repeated 4-6 weekly injections for about 3-4 month.