Age Related Macular Degeneration


What is macular degeneration?

Macular degeneration is damage or breakdown of the macula. The macula is a small area at the back of the eye that allows us to see fine details clearly. When the macula doesn’t function correctly, we experience blurriness or darkness in the center of our vision. Macular degeneration affects both distance and close vision, and can make some activities – like threading a needle or reading – difficult or impossible.

Although macular degeneration reduces vision in the central part of the retina, it does not affect the eye’s side, or peripheral vision. For example, you could see the outline of a clock but not be able to tell what time it is.

Macular degeneration alone does not result in total blindness. People continue to have some useful vision and are able to take care of themselves.

What causes macular degeneration?

Many older people develop macular degeneration as part of the body’s natural aging process.

The two most common types of age-related macular degeneration are “dry” (atrophic) and “wet” (exudative):

“Dry” macular degeneration (atrophic)

Most people have “dry” macular degeneration. It is caused by aging and thinning of the tissues of the macula. Vision loss is usually gradual.

“Wet” macular degeneration (exudative)

“Wet” macular degeneration accounts for about 10% of all cases. It results when abnormal blood vessels form at the back of the eye. These new blood vessels leak fluid or blood and blur central vision. Vision loss may be rapid and severe.

But when both eyes are affected, the loss of central vision may be noticed more quickly.

Following are some common ways vision loss is detected:

  • Words on a page look blurred
  • A dark or empty area appears in the center of vision
  • Straight lines look distorted, as in the following diagram:
  • How is macular degeneration diagnosed?

Many people do not realize that they have a macular problem until blurred vision becomes obvious. Your ophthalmologist (medical eye doctor) can detect early stages of macular degeneration during a medical eye examination that includes the following:

  • Viewing the macula with an ophthalmoscope
  • A simple vision test in which you look at a grid resembling graph paper
  • Sometimes special photographs, called angiograms, are taken to find abnormal blood vessels under the retina. Fluorescent dye is injected into your arm and your eye is photographed as the dye passes through the blood vessels in the back of the eye.

How is macular degeneration treated?

Despite ongoing medical research, there is no cure yet for “dry” macular degeneration. Some doctors believe that nutritional supplements may slow macular degeneration, although this has not yet been proven. Treatment of this condition focuses on helping a person find ways to cope with visual impairment.

Wet Age-related Macular Degeneration (AMD) can be treated with intraocular injection of a class of medications called VEGF inhibitors. VEGF-I stands for Vascuclar Endothelial Growth Factor Inhibitor and these medications target VEGF and inhibit the growth of subretinal neovascular tissue which is thought to be the main culprit that leads to wet macular degeneration. Wet AMD can also be treated with laser surgery, a brief and usually painless outpatient procedure. Laser surgery uses a highly focused beam of light to seal the leaking blood vessels that damage the macula. Although a small, permanently dart “blind spot” is left at the point of laser contact, the procedure can reserve more sight overall.

Despite advanced medical treatment, many people with macular degeneration still experience some vision loss.

Your ophthalmologist can prescribe optical devices or refer you to a low-vision specialist or center. A wide range of support services and rehabilitation programs are also available to help people with macular degeneration maintain a satisfying lifestyle.

Because side vision is usually not affected, a person’s remaining sight can be very useful. Often, people can continue with many of their favorite activities by using low-vision optical devices such as magnifying devices, closed-circuit television, large-print reading materials,, and talking or computerized devices.

Testing your vision with the Amsler grid

You can check your vision daily by using an Amsler grid like the one picture here. You may find changes in your vision that you wouldn’t notice otherwise. Putting the grid on the front of your refrigerator is a good way to remember to look at it each day.

amsler grid

Print the grid to perform the test.

To use the grid:

  1. Wear your reading glasses and hold this grid at 12-15 inches in good light.
  2. Cover one eye.
  3. Look directly at the center dot with the uncovered eye.
  4. While looking directly at the center dot, note whether all lines of the grid are straight or if any areas are distorted, blurred or dark.
  5. Repeat this procedure with the other eye.
  6. If any area of the grid looks wavy, blurred, or dark, contact your ophthalmologist immediately.

Adapted from Wikipedia
http://en.wikipedia.org/wiki/Macular_degeneration