What is Macular Degeneration?
Macular degeneration (MD) is a disease that gradually damages the macula which is the central part of the retina. The macula is responsible for providing the sharp, central vision we need for reading, identifying objects, recognizing faces and even driving. The macula works best in bright light and is also responsible for providing most of our color vision.
In some cases, macular degeneration advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes.
Macular degeneration is a leading cause of vision loss in Americans 60 years of age and older and hence is also called Age-Related Macular Degeneration (AMD). There are many other types of disorders that can be called “macular degeneration” including Juvenile Macular Degeneration (Stargardt’s Disease), Macular holes, Best’s Disease, and Epiretinal membranes (Macular pucker). There are numerous other disorders that can also affect central vision including Albinism, Achromatopsia, Diabetes, Multiple Sclerosis (MS), Optic Atrophy, Nystagmus, Micro- ophthalmia, Coloboma, Rod-Cone Dystrophy, and Myopic degeneration to name just a few.
Age-Related Macular Degeneration occurs in two forms:
- Dry Age-Related Macular Degeneration (Dry AMD): The retina tissues atrophy slowly over time
- Wet Age-Related Macular Degeneration (Wet AMD): Vessels beneath the retina begin to grow and leak causing swelling and other complications that can cause a sudden and potentially dramatic reduction in vision.
Fortunately, macular degeneration is limited to the central retina, so that the peripheral retina, responsible for side (peripheral) vision and motion detection remains intact. Individuals with Age-Related Macular Degeneration will never go totally blind. In fact, individuals can usually walk and engage in most domestic activities with little difficulty due to their vision.
Dry Age-Related Macular Degeneration (Dry AMD)
Dry Age-Related Macular Degeneration (Dry AMD) occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As Dry Age-Related Macular Degeneration (Dry AMD) gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye.
The most common symptom of Dry Age-Related Macular Degeneration (Dry AMD) is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry Age-Related Macular Degeneration (Dry AMD) generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected.
One of the most common early signs of Age-Related Macular Degeneration is drusen.
Drusen are yellow deposits under the retina. They often are found in people over age 60. Drusen alone do not usually cause vision loss. In fact, scientists are unclear about the connection between drusen and Age-Related Macular Degeneration. They do know that an increase in the size or number of drusen raises a person’s risk of developing either advanced Dry Age-Related Macular Degeneration (Dry AMD) or Wet Age-Related Macular Degeneration (Wet AMD).
Wet Age-Related Macular Degeneration (Wet AMD)
Wet Age-Related Macular Degeneration (Wet AMD) occurs when abnormal blood vessels under the retina start to grow beneath the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye damaging the macula, often rapidly.