There are two types of AMD:
Dry, or atrophic, AMD (also called non-neovascular AMD)
Most people who have AMD have the dry form. This condition is caused by aging and thinning of the tissues of the macula. Macular degeneration usually begins when tiny yellow or white pieces of fatty protein form under the retina. These deposits are called drusen. Eventually, the macula may become thinner and stop working properly. With dry AMD, vision loss is usually gradual.
People who develop dry AMD must carefully and constantly monitor their central vision. If you notice any changes in your vision, you should tell your ophthalmologist (Eye M.D.) right away, as the dry form can change into the more damaging form of AMD called wet (exudative) AMD.
Monitoring your vision
If you have been diagnosed with dry AMD, you should use a chart called an Amsler grid every day to monitor your vision, as dry AMD can change into the more damaging wet form.
To use the Amsler grid, wear your reading glasses and hold the grid 12 to 15 inches away from your face in good light.
- Cover one eye.
- Look directly at the center dot with the uncovered eye and keep your eye focused on it.
- While looking directly at the center dot, note whether all lines of the grid are straight or if any areas are distorted, blurry or dark.
- Repeat this procedure with the other eye.
- If any area of the grid looks wavy, blurred or dark, contact your ophthalmologist immediately.
If you detect any changes when looking at the grid, you should notify your ophthalmologist immediately.
Wet, or exudative, AMD (also called neovascular AMD)
The wet form of macular degeneration occurs in about 10 percent of all macular degeneration cases, but it can cause more damage to your central or detail vision than the dry form.
Capillaries, or tiny blood vessels, extend into all tissues of the body, bringing in nutrients and carrying off waste products. Capillaries usually don’t increase in size or number, but if they do, it is called abnormal blood vessel growth.
Wet AMD occurs when abnormal blood vessels begin to grow underneath the retina. This blood vessel growth is called choroidal neovascularization (CNV) because these vessels grow from the layer under the retina called the choroid. These new blood vessels may leak fluid or blood, blurring or distorting central vision. Vision loss from this form of AMD may be faster and more noticeable than that from dry AMD.