Age-Related Macular Degeneration Diagnosis & Tests

How Is Age-Related Macular Degeneration Diagnosed?

Age-related macular degeneration can be detected in a routine eye exam. One of the most common early signs of macular degeneration is the presence of drusen -- tiny yellow deposits under the retina. Your doctor can see these when examining your eyes. Your doctor may also ask you to look at an Amsler grid -- a pattern of straight lines that resemble a checkerboard. Some of the straight lines may appear wavy to you, or you may notice that some of the lines are missing. These can be signs of macular degeneration.

If your doctor detects age-related macular degeneration, you may have a procedure called fluorescein angiography. In this procedure, a dye, called fluorescein, is injected into a vein in the arm. Photographs are taken to show the movement of the dye as it reaches the eye and passes through the blood vessels of the retina. If there are new vessels leaking fluid or blood in the macula, the photographs will show their exact location and their type.

Early detection of age-related macular degeneration is very important because there are treatments that can delay or reduce the severity of the disease.

Age-Related Macular Degeneration Tests

Initial tests include measurement of the sharpness of vision and an examination of the retina. During the examination of the retina, the ophthalmologist looks for specific signs of macular degeneration.

• Multiple spots in the macular region become the hallmark of the dry form of age-related macular degeneration. These spots are accumulations of fat and cellular debris under the pigmented outer layer of the retina. They appear as white to yellow dots that will merge together with time. The spots may cause mild to moderate loss of central vision.
• Another sign of age-related macular degeneration is degeneration of the pigmented layer itself. Degeneration appears as thinning and loss of the retina, the pigment layer, and the choroid, one of the outer layers of the eyeball. Loss of vision tends to be moderate. It causes blind spots (called scotomas) next to central vision. If degeneration of the pigment layer affects the center of the macula, a person can lose vision.
• In eyes that become complicated by the wet form of age-related macular degeneration, fluid, blood, scarring, and new blood vessel membranes below the retina might be seen. These abnormalities may progress rapidly over days to months. Eventually, they may result in profound irreversible central vision loss. Wet age-related macular degeneration reduces vision sharpness to 20/200 or worse within two years in 70% of affected eyes.

If signs of age-related macular degeneration are found, an ophthalmologist may take detailed pictures of the retina for future comparison. Tests may also include:

• Fluorescein angiography: A special dye is injected into the arm. Then, an ophthalmologist photographs the retina as the dye passes through the retina. This test determines if laser treatment is necessary and, if so, the location of the treatment.
• Indocyanine green angiography: This test uses infrared wavelengths to view the retina. The test may help to identify signs of macular degeneration that cannot be seen with fluorescein angiography.
• Optical coherence tomography (OCT): This represents a noninvasive examination technique that produces a cross-sectional image of the posterior retina in vivo. Although this method is now widely applied in the diagnosis of various macular disorders, its role in evaluation and follow-up of patients with age-related macular degeneration is not well established.
• Microperimetry using the Rodenstock scanning laser ophthalmoscope: This is used to quantify macular sensitivity and fixation pattern.