Age-related macular degeneration affects nearly 2 million Americans. More than 7 million Americans are at substantial risk for developing age-related macular degeneration. Some estimate that nearly 3 million people will be affected by 2020. Macular degeneration is the leading cause of central visual impairment that affects reading, driving, recognizing faces and performing close-up work among people aged 65 and above.
What Causes Age-Related Macular Degeneration?
The exact way age related macular degeneration develops is unknown. But, oxidative stress of the retina is thought to be a major contributor. The high concentration of oxygen and exposure to intense light seem to make the retina susceptible to oxidative damage.
Smoking is a well known way to deplete antioxidants. Smoking also increases blood viscosity and constricts blood vessels thus reducing the blood flow to the eyes. Every cigarette you smoke does damage to your eyes.
As the name (“age-related” macular degeneration) implies, age also plays its part. The aging of the retinal pigment epithelial layer and Bruch’s membrane (the layer below the epithelial layer) can allow the accumulation of debris and drusen. And, any existing abnormality typically worsens with age causing further damage and dysfunction of the retinal pigment epithelial layer.
Once the retinal pigment epithelial cells are damaged they secrete several growth factors including vascular endothelial growth factor (VEGF) which encourages the growth of new blood vessels (choroidal neovascularization) that cause problems in the “wet” form of age-related macular degeneration.
High BMI (body mass index) is also associated with increases in the late stage of the dry form of age related macular degeneration. Those in the obese category (BMI>30) compared to those with a “normal” BMI (ranging from 18.5 to 24.9) had nearly twice the incidence of this severe form of macular degeneration.
Exposure to bright, ultra-violet light increases (as does oxidative stress) after cataract surgery because the human lens helps reduce ultra-violet transmission to the retina.
Cardiovascular disease along with high cholesterol and hypertension (high blood pressure) are associated with the “wet” or neovascular age-related macular degeneration. Even subclinical cardiovascular disease with plaques in the artery walls increases the likelihood of late state age-related macular degeneration by 5 times.
Genetics can predispose a person to get age-related macular degeneration. It is more prevalent in some families indicating a genectic factor. Genetics along with environmental stress make the disease more likely. Certain chromosomal regions seem to be associated with the disease, including 1q31–32, 6q21 and 10q26.
A poor diet low in antioxidants, low in omega-3 fatty acids, and low in leafy green vegetables does not provide protection. Unfortunately, the increasingly popular habit of eating manufactured foods and at fast food restaurants is leading, in many ways, to a sick population that is getting sicker as the years go by.
Difference Between Wet and Dry Macular Degeneration
While that main effect of age-related macular degeneration is the reduction in central vision, there are two causes for this impariment. They are designated “dry” and “wet” macular degeneration.
Dry age related macular degeneration is characterized by “drusen” which are yellow deposits forming under the macula. As these deposits build up they cause the retinal pigment epithelium and photoreceptors to atrophy. There are three stages of dry age related macular degeneration: early, intermediate and late. These stages are characterized by the size of the drusen deposits and the degree of athrophy in the retinal pigment epithelium and photoreceptors. The intermediate stage is when a person begins have trouble reading, recognizing faces, and having trouble adapting to changes in lighting.Wet age-related macular degeneration is caused by the abnormal growth of blood vessels under the retina. These blood vessels are delicate and often leak, producing a spontaneous hemorrhage. The scarring from the broken vessels causes irreversible damage to the macula. Such damage produces the most drastic loss of central vision. This “wet” version can develop on its own or it can be the result of the “dry” version.
Around 90% of age related macular degeneration is of the “dry” variety while 10% is the “wet” variety.
What is Macular Degeneration?
Macular degeneration is a disease which affects the retina. In this video we will describe the symptoms of macular degeneration. The retina is the layer at the back of the eye which helps us to see the world around us.
First Signs of Macular Degeneration
Before any visual problems are noticed an ophthalmologist can detect drusen within the retina.
Drusen are small yellow or white deposits just under the retina. While the presence of drusen in people over aged 60 is normal, the risk of age-related macular degeneration increases significantly when the drusen are large or are numerous. The thickness of the drusen is related to the degree of degeneration of the retinal pigment epithelium and vision loss.
Can Macular Degeneration be Prevented?
Preventive measures usually fall under three categories:
A number of nutritional clinical trials have been conducted to determine what nutrients work to delay or prevent age-related macular degeneration.
AREDS Formulation of Nutritional Supplements
The “Age-Related Eye Disease Study” and the followup study “Age-Related Eye Disease Study 2” produced formulations of nutrients that reduced the risks of advancing to the advanced stage of age-related macular degeneration.
But, it was noticed that the vitamin A as beta carotene seemed to increase cancer risks in mostly former smokers. A second study (AREDS2) was performed to replace beta carotene. The final formulation consists of:
- Antioxidant vitamin C
- Antioxidant vitamin E
- Omega-3 long-chain polyunsaturated fatty acids
- Lutein + Zeaxanthin
Does everyone need to take the AREDS2 vitamins for their eye health?
Lutein and zeaxanthin are carotenoids (plant pigments) that exist in high concentrations in the macula. They act as short-wavelength light filters that help reduce oxidation. Because the human body cannot make lutein, it must come from the diet or supplements.
Neither lutein nor zeaxanthin were available during the first AREDS study because they could not be manufactured in a research formulation. But, they are now available from several reliable sources.
Omega-3 fatty acids have been known for some time to help reduce cardiovascular disease and strokes. Its qualities of helping to reduce inflammation and regulate the autoimmune response make it an ideal addition the to AREDS2 formulation to help prevent the advance of age-related macular degeneration.
Many people are interested in berries for their antioxidant properties. Though not extensively studied, the most important berries for their antioxidant properties are:
- Goji berry (also called wolfberry)
- Anthocyanin (found in blueberry, raspberry, black rice, and black soybean)
Lifestyle changes include:
- Smoking cessation
- Reducing BMI
- Reducing light exposure (sunglasses)
Can Drugs Reverse Macular Degeneration?
There are currently no drug treatments to regain lost vision.
FDA accepted treatments are available for the “wet” form of age-related macular degeneration only. These drugs are intended to prevent the further creation of additional blood vessels under the retina. As already mentioned, the deterioration of the retinal pigment epithelial cells produce vascular endothelial growth factor (VEGF) which encourages the growth of these new, weak blood vessels. The treatment involves injecting anti-VEGF drugs into the eye near the retina.
The costs for these drugs is high and multiple injections are required.
At the time this is written there are 322 clinical trial in progress dealing with macular degeneration. A few of these are:
- Managing Neovascular (Known as “Wet”) Age-related Macular Degeneration Over 2 Years Using Different Treatment Schedules of 2 mg Intravitreal Aflibercept Injected in the Eye
- Evaluation of Visual Function and Driving Health Using Ocusweep in Patients Suffering From Wet Age-related Macular Degeneration
- Age-related Macular Degeneration (AMD) in the Vitamin D and Omega-3 Trial (VITAL)
- Clinical Study of Subretinal Transplantation of Human Embryo Stem Cell Derived Retinal Pigment Epitheliums in Treatment of Macular Degeneration Diseases
Conclusions You Can Use
While you cannot do anything about your genetic makeup, you can take steps to reduce your likelihood of reaching a stage of age-related macular degeneration that interferes with your central vision. This involves simple habits that everyone should develop. These include:
- Eat healthy foods
- Lose excess weight
- Take supplements
- Age-related macular degeneration and the aging eye from the journal Clinical Interventions in Aging
- Double-masked, placebo-controlled, randomized trial of lutein and antioxidant supplementation in the intervention of atrophic age-related macular degeneration: the Veterans LAST study (Lutein Antioxidant Supplementation Trial) from the journal Optometry
- Prevention of age-related macular degeneration from the journal International Ophthalmology
- Lutein + zeaxanthin and omega-3 fatty acids for age-related macular degeneration: The Age-Related Eye Disease Study 2 (AREDS2) randomized clinical trial from the journal Ophthalmology
- Laser Treatment in Patients with Bilateral Large Drusen The Complications of Age-Related Macular Degeneration Prevention Trial from the journal Ophthalmology
- Dietary ω-3 Fatty Acid and Fish Intake in the Primary Prevention of Age-Related Macular Degeneration from the journal Archives of Ophthalmology
- Dietary antioxidants and primary prevention of age related macular degeneration: systematic review and meta-analysis from the British Medical Journal
- EVALUATION OF CURCUMIN-LOADED NANOLIPOSOMES FOR THE TREATMENT AND PREVENTION OF AGE-RELATED MACULAR DEGENERATION a
Thesis submitted in partial fulfillment of the requirements of the Gemstone Program University of Maryland, 2017