Testing and Diagnosis
Reviewed by: HU Medical Review Board | December 2018
With the varying speed of progression and prevalence of the different types of macular degeneration, having an early diagnosis is never a guarantee. With a comprehensive eye exam and additional testing to evaluate eye health, your doctor can see the signs indicative to each type and make a proper diagnosis.
How do vision tests help diagnose macular degeneration?
Which vision tests help diagnose macular degeneration?
Visual acuity test
A visual acuity test is the standard eye chart exam, which measures how well you can see a letter, number, or symbol from a certain distance. The doctor will often have you read lines with each eye individually with the other one covered, and may also ask you to read with both eyes.
A test using the Amsler grid can determine whether you are having any visual distortions. In this test, a grid of straight lines is presented, and one eye is covered while you look at the central dot. As you look at that dot, look to see if all of the lines in your visual field are straight, or if they are wavy; repeat with the other eye covered.1 This test is also something you can do at home to monitor for any vision changes.
Visual field testing
A visual field test is used to determine whether or not an individual has any blind spots, or scotomas and provides eye care professionals with an idea of how wide their peripheral vision is. In this test, one eye is covered, while the other eye fixates on a target in your peripheral vision. An eye doctor may hold up a certain number of fingers and ask you how many you can see.
How does a dilated eye exam diagnose macular degeneration?
During the dilated eye exam, dilating eyedrops are placed in your eyes to enlarge (dilate) the pupils. This lets light into the eye and allows your eye doctor to look inside of the eye and get better views of the retina, optic nerve, blood vessels, and other structures within the eye.2 In many eye diseases, including macular degeneration, there will be changes to these tissues and structures, and without a dilated eye exam, the doctor will not be able to identify these changes.
How does a fluorescein angiogram diagnose macular degeneration?
A fluorescein angiogram might be done if your ophthalmologist suspects you have wet AMD. She will inject a vein in your arm with a fluorescent dye, and as the dye goes through the blood vessels in your eyes, she will take special pictures.3 This can show whether any blood vessels are leaking, blocked, or otherwise abnormal.
How dos an OCT scan diagnose macular degeneration?
Optical coherence tomography is similar to ultrasound, but instead of using sound waves, it uses light to obtain images of tissues. After your eyes are dilated, a special machine will shine a light beam at your eyes to visualize the retina and underlying ocular structures.3