Age-Related Macula Degeneration, short AMD
Anatomy of the retina and macula
The retina is the sensory membrane that lines the inner surface of the back of the eyeball. It’s composed of several layers, including one that contains specialized cells called photoreceptors (rods and cones). The rods are more sensitive than the cones, so in dim light they are the dominant photoreceptors.
The macula is a pigmented area near the center of the retina of the human eye. It contains a high density of cones, thus this structure is sepcialized for high acuity vision (central, high- resolution, color vision) that is possible in good light. This kind of vision is impaired if the macula is damaged, for example in macular degeneration.
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Definition of AMD
AMD is the leading cause of severe, permanent vision loss in people over age 60. It happes when the photoreceptor cells of the macula are damaged. Because the disease happens as you get older it´s called age- related. It usually doesn’t cause blindness but might cause severe vision problems..
Who is in risk of getting an AMD?
Basically, every person is exposed to the risk of age-related macular degeneration throughout their lives, as we are always exposed to UV light.However, whether the individual ever gets an AMD can not be predicted.
Known risk factors are:
- abnormal exposition to UV- light
- positive family history and genetics
- age (60 years and above)
- cardiovascular diseases (e.g. high blood pressure, diabetes mellitus, arteriosclerosis)
Types of AMD
Dry macular degeneration
Dry AMD is characterized mainly by the change in the macula due to metabolic waste products (drusen), which are stored inside the retina. However, in this form there is no leakage of tissue fluid, hence called „dry form“.
A few small drusen may not cause changes in your vision. But as they get bigger and more numerous, they might dim or distort your vision, especially when you read. As the condition gets worse, the light-sensitive cells in your macula get thinner and eventually die. In the atrophic form, you may have blind spots in the center of your vision. As that gets worse, you might lose central vision.
Dry AMD usually affects both eyes. If only one eye is affected, you may not notice any changes in your vision because your good eye may compensate for the weak eye. The dry type is more common and usually progresses slowly (over years). It can progress to a wet (neovascular) macular degeneration.
Wet macular degeneration
Blood vessels grow from underneath your macula. These blood vessels leak blood and fluid into your retina. As a result of the leakage the retina will swell (edema). Your vision is distorted so that straight lines look wavy. The wet type is more likely to cause a relatively sudden change in vision resulting in serious vision loss. You may also have blind spots. Uncontrolled bleeding will cause a macular scar over time, leading to permanent loss of vision.
- Visual distortions, such as straight lines seeming bent
- Reduced central vision in one or both eyes
- The need for brighter light when reading or doing close work
- Increased blurriness of printed words
- Decreased intensity or brightness of colors
- Difficulty recognizing faces
Examination of the back of your eye
Your eye doctor will put drops in your eyes to dilate them and use a special instrument to examine the back of your eye. He or she will look for a mottled appearance that’s caused by drusen — yellow deposits that form under the retina. People with macular degeneration often have many drusen.
During this test, your doctor injects a colored dye into a vein in your arm. The dye travels to and highlights the blood vessels in your eye. A special camera takes several pictures as the dye travels through the blood vessels. The images will show if you have abnormal blood vessel or retinal changes.
Optical coherence tomography
This noninvasive imaging test displays detailed cross-sectional images of the retina. It identifies areas of retina thinning, thickening or swelling. These can be caused by fluid accumulations from leaking blood vessels in and under your retina.
Test for defects in the center of your vision
Das Amsler-Gitter (During an eye examination, your eye doctor may use an Amsler grid to test for defects in the center of your vision. Macular degeneration may cause some of the straight lines in the grid to look faded, broken or distorted.
Therapy of AMD
- Don’t smoke or quit smoking
- Choose a healthy diet
- UV- protection from harmful short- wave blue ultraviolet light components by wearing a pair of (sun)glasses. Ask your optician for further advice. Also, if cataract- surgery hasn’t been performed yet, intraocular lenses with 100% UV protection can be chosen. Ask your eye doctor for further advice.
- Manage your other medical conditions – If you have cardiovascular disease (high blood pressure, ateriosclerosis, diabetes mellitus etc.) take your medication and follow your doctor’s instructions for controlling the condition.
- Maintain a healthy weight and exercise regularly – If you need to lose weight, reduce the number of calories you eat and increase the amount of exercise you get each day.
- Have routine eye exams
A number of findings suggest taking a high-dose formulation of antioxidant vitamins and minerals may favorably influence the course of some forms of AMD and help reduce the risk of vision loss.
These substances are:
Ask your ophthalmologist, he or she will recommend you the correct preparation.
Unfortunately, medication for dry AMD does not exist yet. However, scientific studies (called AREDS 1 and AREDS 2) proved that the intake of micronutrients with the above mentioned ingredients have a positive influence on the progression of the disease.
Treatments are available that may help slow disease progression, preserve existing vision and, if started early enough, recover some lost vision.
These may help stop the growth of new blood vessels by blocking the effects of growth signals the body sends to generate new blood vessels. These drugs are considered the first line treatment for all stages of wet macular degeneration.
Medications used to treat wet macular degeneration include:
- Bevacizumab (Avastin)
- Ranibizumab (Lucentis)
- Aflibercept (Eylea)
Your doctor injects these medications into the affected eye. You may need injections every four weeks to maintain the beneficial effect of the medication. In some instances, you may partially recover vision as the blood vessels shrink and the fluid under the retina absorbs, allowing retinal cells to regain some function.
Help for the visually impaired
Low vision aids. These are devices that have special lenses or electronic systems to create larger images of nearby things. They help people who have vision loss from macular degeneration make the most of their remaining vision.
- AMD never leads to blindness
- Early diagnosis is very important for the outcome of the disease
- Compliance – once a patient is diagnosed with AMD, regular check-ups are very important to manage the disease
- intravitreal injections are first line therapy in wet macular degeneration. These method is far advanced nowadays