"The doctor knows best" is a familiar adage to most of us. We set great store by the judgment of our physicians, nurses, and other providers. Yet no matter how much faith we place in those who care for us, we must not neglect our responsibility to look after our own health between office visits.
Learning about your condition and being aware of your symptoms gives the experts--your health care providers--the best chance of being able to intervene effectively if something goes wrong. This awareness is especially important for those who are at risk of age-related macular degeneration (AMD) or who have early- or intermediate-stage AMD. That's because early detection of the onset of wet (advanced) AMD can significantly reduce the risk of AMD--related vision loss.
If you don't have AMD, it's essential to recognize its first symptoms (find out what those are by reading Symptoms of Age-Related Macular Degeneration). If you have early- or intermediate-stage AMD, it's critical to monitor your vision daily and to understand the type and stage of disease you have.
Screening
To detect AMD before symptoms appear, you should be screened if you meet any of the following criteria:
- Over the age of 60
- Have hypertension or cardiovascular disease
- Smoke cigarettes or other tobacco products
- Have a close relative (sibling, parent, or child) with AMD--related vision loss, regardless of your age
- Have had cataract surgery (replacement of the crystalline lens of the eye with an artificial lens)
- Have had significant cumulative light exposure (e.g., airline pilots, boaters, farmers)
Comprehensive eye examination
Visual acuity testing.
Most of us are familiar with the "big E" eye chart, so named for the large block letter at the top. This visual acuity chart measures how well you see at various distances. From a specified distance, usually 20 feet, your vision care provider will ask you to read aloud progressively smaller rows of capital letters. Progress or further decline of AMD is measured in terms of how many letters you can read on the chart after a period of weeks, months, or years. For example, a person might lose the ability to read 15 letters (three lines) in an 18-month period.
Ophthalmoscopy followed by slit-lamp examination.
Your vision care provider will view the retina using a hand-held, or head-mounted instrument called an ophthalmoscope. First, special drops will be instilled to dilate your pupils, revealing the internal structures of the eye. After this examination, a slit lamp, which is a high-intensity light source combined with a low-power microscope, will be used to examine the frontal structures of the eye.
Tonometry.
A tonometer is a hand-held instrument that measures intraocular pressure (the pressure of fluids inside the eye) after anesthetic (numbing) drops are instilled. This test is performed to rule out glaucoma.
Supplemental Testing
Amsler grid
The appearance of wavy, broken, or gray lines on an Amsler grid (see illustration, or visit our Amsler Grid page for more information) is a strong indication that you have macular degeneration. An Amsler grid is a simple chart composed of horizontal and vertical black lines on a white background with a black dot at the center. If you have AMD, staring at the center dot will make the grid lines around it appear blurry or distorted. Some people may even see blank spots on the grid. But to make a definitive diagnosis, your vision care provider must look at the retina.
Angiography
Fluorescein is a dye that's administered intravenously (injected into a vein) and taken up by vessels of the eye, allowing your eye doctor to visualize vessels in your choroid and retina to check for neovascularization and RPE detachment (see Overview of Age-Related Macular Degeneration for a brief explanation of these processes). A similar dye called indocyanine green may also be used to obtain additional information about the vasculature (vessel structure) of your eye. Eye diseases other than AMD can cause abnormal vessel growth, so your vision care provider must assess the extent, type, and location of the new vessels and carefully consider your signs and symptoms in order to diagnose AMD.
Optical coherence tomography
Optical coherence tomography (OCT) is a test that produces high-resolution images of cross-sections of the retina, allowing its thickness to be measured. Areas of thinning may indicate macular degeneration. This test can also show abnormal fluid build-up in and under the retina. OCT works like ultrasound, except that it measures scattered light instead of sound waves.
Understanding Your Diagnosis
Early detection of the onset of wet AMD is essential to preserving vision. That's why it's important to learn everything you can about AMD. Arrive for your appointments prepared with notes on your symptoms, if possible, and ask questions about anything you don't understand. Take an active role in preventing vision loss--doctor's orders.
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