What is macular degeneration?
Age-related macular degeneration affects the area of the retina called the macula. This small area is responsible for producing sharp, central vision required for "straight ahead" activities such as driving, reading, recognizing faces and performing close-up work. While scientists are uncertain of its cause, AMD can advance so slowly that people hardly notice it developing ("dry" AMD) or it can rapidly progress to the point of vision loss in one or both eyes ("wet" AMD).
What is "dry" AMD?
Dry AMD causes the slow deterioration of the macula's light-sensitive cells. The presence of drusen or tiny yellow deposits in the retina is one of the earliest signs of AMD, and these can be detected with a dilated eye exam. Drusen can block necessary nutrition that is needed in the eye. Over time, the retinal tissue can waste away around these areas and spotty vision occurs. Sometimes several of these areas merge, giving the macula a moth-eaten appearance that leads to a progressive loss of vision. Although the presence of drusen alone is not indicative of the disease, it may indicate the eye is at risk for developing more severe AMD.
What is "wet" AMD?
Just below the surface of the retina are layers of photoreceptors that are highly active and very sensitive. These photoreceptors require a lot of energy and a constant and rich supply of nutrients. Anything that interferes with the flow of these nutrients can cause the macula to malfunction and perhaps become diseased. In "wet" AMD, new blood vessels from behind the retina leak onto the macula and quickly destroy it. In the beginning stages, straight lines appear wavy and fine details fade. It becomes hard to focus on just one word and faces start to blur. People gradually lose the ability to read or drive and often progress to legal blindness. The "wet" form of AMD occurs in only 10% of all cases, but it is responsible for 90% of decreased vision resulting from AMD.
What is an “Amsler grid”?
Below is a simple screening test you can use at home. It is called an Amsler Grid. Patients can use it to detect early signs of macular degeneration or for monitoring any further deterioration. Holding the grid at arms-length, stare at the center dot. Are any of the lines crooked, bent, wavy or missing? If they are, please seek the immediate attention of an eye care professional at Hollingshead Eye Center. This test does not replace a professional exam.
How the Eye Works
The eye’s surface, or the cornea, is convex. A well-shaped cornea allows light rays that hit it to bend through the pupil, pass through the lens, and focus precisely on the retina at the back of the eye. The retina converts the light rays into electrical impulses that are sent through the optic nerve to the brain, where a clear image is produced.