What Is Age-Related Macular Degeneration?
Age-related macular degeneration (AMD) is an eye disease in which the center of the retina is progressively damaged, leading to gradual central vision loss. The macula, found at the center of the retina, is responsible for producing central vision [1,2].
Symptoms and their severity depend on which of the two types of AMD you have, either "dry" or "wet." However, you are likely to experience a gradual loss of central vision, dark spots in your vision, and a distortion in the appearance of straight lines.
Treatments differ by type, but may include medication or procedures, supplements, and lifestyle modifications to either limit or prevent AMD.
You should visit your primary care physician within a few weeks to discuss your symptoms. The diagnosis will be made via eyesight tests.
How common is Age-Related Macular Degeneration?
Symptoms that always occur with Age-Related Macular Degeneration:
- Vision changes
Age-Related Macular Degeneration is also known as
- Age-related maculopathy (ARM)
- Macular degeneration
- Nonexudative ("dry") AMD
- Exudative ("wet") AMD
Age-Related Macular Degeneration Symptoms
Early AMD usually does not cause any symptoms, as the gradual loss in vision will occur if the AMD advances. Wet AMD typically causes more severe symptoms than dry AMD, including dark spots in your vision and a distortion of straight lines. Wet AMD is the cause of 90 percent of cases of legal blindness among patients with AMD . However, dry AMD is the more common type, present in about 80 percent of people with AMD .
Symptoms of dry and wet AMD
You will likely experience the first symptom in both forms of AMD, and the two latter in wet AMD. Details include:
- Gradual, painless loss of central vision: The vision loss initially occurs slowly over months to years, but may develop faster once wet AMD develops. Vision loss usually develops first in one eye, but may subsequently develop in the other eye. Vision loss may first be noticed as difficulty reading or driving.
- Dark spots in the vision ("scotoma"): Some people with AMD may develop dark spots in their vision, known as scotoma. Scotomas are more common in people with wet AMD.
- Distortion of straight lines ("metamorphopsia"): Straight edges such as the sides of doors or windows may appear curved.
Age-Related Macular Degeneration Causes
The retina is the "film" in the back of the eye that senses light to produce vision, and the center of the retina is known as the macula, which is what progressively becomes damaged.
- Dry AMD: Abnormal deposits of debris called drusen develop in the retina, and specific cells in the retina degenerate and become lost. The name "dry" refers to the fact that there are no abnormal blood vessels that cause leakage of fluid in dry AMD . Over time, dry AMD can develop into wet AMD.
- Wet AMD: New, abnormal blood vessels grow into the retina, causing bleeding and severe vision loss. Wet AMD is associated with leakage of these blood vessels, suggesting the name.
There are a number of factors that contribute to the development of AMD besides age, including lifestyle habits, decreased blood flow to the eye, abnormal blood vessel growth in the eye, family history and genetics, and cardiovascular disease [4,6].
Age and lifestyle habits
Older age is the main risk factor for developing AMD. AMD affects 4.6 percent of people aged 75 to 84 years and 13.1 percent of people older than 84 years old . Other lifestyle factors may contribute as well. Details include:
- Age: The specific way in which age leads to AMD is not clear, but likely has to do with cumulative damage to the retina from decreased blood flow and inflammation, which are described below.
- Smoking: People who currently smoke have approximately a two to three times higher risk of developing AMD compared to people who have never smoked . In addition, smoking increases the risk of progressing from dry AMD to wet AMD.
- Diet: In one study, people who ate a healthy diet high in fruits, vegetables, and whole grains and low in saturated fat, sodium, and added sugar had a 46 percent lower odds of developing AMD than people who did not eat a healthy diet .
Decreased blood flow
Decreased blood flow to specific parts of the retina is thought to contribute to the development of drusen, and thus, dry AMD. In addition, decreased blood flow may stimulate the growth of abnormal blood vessels to compensate, which can cause wet AMD.
Abnormal blood vessel growth
Abnormal new blood vessel growth near the retina leads to the development of wet AMD. When certain cells in the retina are damaged from insufficient blood flow, they release a factor called vascular endothelial growth factor (VEGF). This factor stimulates the growth of abnormal new blood vessels, which can lead to bleeding in the retina.
Family history and genetics
There is believed to be a genetic component with AMD, resulting in likely inheritance.
- Family details: Studies of twins have revealed genetic factors in AMD, and having a parent, child, or sibling with AMD increases a person's risk for AMD by three to four times .
- Genetics details: There are currently 52 different genetic variants associated with AMD . One specific genetic mutation associated with AMD involves a gene that is important in controlling a part of the immune system. People with this mutation experience increased levels of inflammation, which may contribute to the development of AMD.
Having cardiovascular disease, such as a stroke or heart attack, is associated with an increased risk of developing AMD. This may be related to increased inflammation or decreased blood flow to parts of the retina.
Treatment Options and Prevention
AMD is a chronic condition that cannot be completely cured. However, treatments are available that can slow the progression of the disease and stabilize or reverse vision loss. Treatments generally differ for dry AMD and wet AMD. Specific treatment options include injections, photodynamic therapy, lifestyle changes, and supplements .
Injection of medications into the eye
Most people with wet AMD are treated with injections of vascular endothelial growth factor (VEGF) inhibitor medications into the eye . VEGF is a factor that increases the growth of abnormal blood vessels in the eye and plays a key role in the development of wet AMD.
- Details: These injections can be done in the office with local anesthetics, and are generally administered once a month, although some physicians may administer them more or less frequently depending on the status of the AMD.
- Types: Commonly used VEGF inhibitor medications include ranibizumab (Lucentis), bevacizumab (Avastin), and aflibercept (Eylea).
- Efficacy: Injecting VEGF inhibitor medications into the eye has been shown to slow the progression of wet AMD and stabilize or even reverse vision loss.
Some people with wet AMD who do not respond to VEGF inhibitor medications may benefit from a treatment called photodynamic therapy.
- Details: A dye is first injected intravenously, and then a laser is applied to the inside of the eye using a contact lens. The laser activates the dye, which preferentially binds to and damages the abnormal blood vessels.
- Efficacy: Photodynamic therapy is effective for blocking abnormal blood vessels, but is associated with a high rate of recurrence .
Smoking has been associated with an increased risk of progressing from dry AMD to wet AMD, and quitting smoking has been shown to decrease the risk of developing wet AMD. Beyond quitting smoking, it is also important to maintain a healthy diet and exercise regularly.
For some people with dry AMD, taking a specific formulation of antioxidants and supplements has been shown to decrease the risk of progressing from dry AMD to wet AMD or for cases of wet AMD in general .
- Details: There are two formulations that have been shown in large clinical trials to reduce the risk of progression from dry AMD to wet AMD, known as "AREDS" and "AREDS2." These formulations generally contain a combination of vitamin C, vitamin E, and zinc, as well as either beta-carotene or lutein and zeaxanthin.
- Types: These formulations are available over-the-counter and include brands such as PreserVision AREDS and AREDS2 formulas and ICAPS AREDS formula.
When to Seek Further Consultation
You should seek medical attention if you develop symptoms of AMD, described below.
If you develop any symptoms of AMD
You should see your eye doctor if you experience a gradual loss of vision, dark spots in your vision, or a distortion of straight lines. Your eye doctor can examine your eye to determine if you have AMD, and then offer the appropriate treatment.
Questions Your Doctor May Ask to Diagnose
To diagnose this condition, your doctor would likely ask about the following symptoms and risk factors.
- Have you been feeling more tired than usual, lethargic or fatigued despite sleeping a normal amount?
- How long has your vomiting been going on?
- How severe is your nausea?
- Has your nausea been constant or come-and-go?
- How many times have you vomited in the last 24 hours?
The above questions are also covered by our A.I. Health Assistant.
- Facts About Age-Related Macular Degeneration. National Eye Institute. Published September 2015. NEI Link
- Boyd K, Janigian RH. What Is Macular Degeneration? American Academy of Ophthalmology. Published May 17, 2018. AAO Link
- Age-Related Macular Degeneration: Facts & Figures. BrightFocus Foundation. Published Jan.5, 2016. BrightFocus Foundation Link
- Mogk LG, Duffy MA. Risk Factors for Age-Related Macular Degeneration (AMD). VisionAware. VisionAware Link
- Dry vs Wet Age-Related Macular Degeneration. American Macular Degeneration Foundation. AMDF Link
- Diet, Exercise, Smoking Habits and Genes Interact to Affect AMD Risk. National Eye Institute. NEI Link. Published September 15, 2015.
- Schwartz SG, Hampton BM, Kovach JL, Brantley MA. Genetics and age-related macular degeneration: a practical review for the clinician. Clin Ophthalmol. (Auckland, NZ). 2016;10:1229-1235. NCBI Link
- Macular Degeneration Treatments. American Macular Degeneration Foundation. AMDF Link
- Nowak-Sliwinska P, Weiss A, Sickenberg M, Griffioen AW, van den Bergh H. The role of photodynamic therapy in non-malignant and malignant eye disorders. J Anal Bioanal Tech. S1:007. Journal of Analytical & Bioanalytical Techniques Link
- Antioxidant Vitamins and Zinc Reduce Risk of Vision Loss from Age-Related Macular Degeneration. National Eye Institute. Published October 12, 2001. NEI Link
- Smith W, Assink J, Klein R, Mitchell P, Klaver CC, Klein BE, Hofman A, Jensen S, Wang JJ, de Jong PT. Risk factors for age-related macular degeneration: Pooled findings from three continents. Ophthalmol. 2001;108(4):697-704. NCBI Link
- Mares JA, Voland R, Sondel SA, Millen AE, LaRowe T, Moeller SM, Klein ML, Blodi BA, Chappel R, Tinker L, Ritenbaugh C, Gehrs K, Sarto G, Johnson EJ, Snodderly M, Wallace RB. Healthy lifestyles related to subsequent prevalence of age-related macular degeneration. Arch Ophthamol. 2011;129(4):470-480. NCBI Link