Since the finest vessels in the human body are found in retinal tissue, risk factors affecting circulation include high blood pressure and cholesterol, diabetes mellitus and smoking. Diet, lifestyle and medication can reduce these risk factors causing vision loss from artery and vein occlusions as well as hypertensive and diabetic retinopathy.
Although treatment exists for improving vision in some of these sight threatening conditions, prevention is the only assurance of maintaining excellent vision. The key to both good general and eye health is long term control of one's blood pressure, cholesterol and blood sugar control.
What is age-related macular degeneration?
Age-related macular degeneration is a retinal dystrophy, meaning it has a genetic component, (several genes have been identified with varying risks in terms of severity of disease) but is multifactorial with risk factors such as smoking, poorly controlled blood pressure and cholesterol posing significant risk for disease progression and for the development of "wet" AMD.
Macular degeneration begins as the dry form in all individuals with this condition and fortunately remains such throughout their lives, with only approximately 15 percent developing abnormal vessels under the retinal macula and bleeding or fluid which can cause sudden loss of central vision. Since the macula provides central vision, one's peripheral or side vision remains unaffected by macular degeneration.
What can you do to prevent AMD?
The macula is the central part of the retina responsible for fine, detailed vision such as reading. Although there is no cure or prevention for age-related macular degeneration, certain factors can be addressed to reduce the risk of disease progression.
If there is a family history of macular degeneration, closer monitoring of the macular status in individuals over age 50 is recommended. Risk factors such as smoking, obesity, hypertension and high cholesterol should also be addressed. Furthermore, diets rich in antioxidants, lutein, zeaxanthin, and omega 3 acids appear to be beneficial.
In 2001, the Age-Related Eye Disease Study (AREDS) demonstrated a benefit from nutritional supplements for those with moderate to severe "dry" macular degeneration. The AREDS supplements included high dose Vitamin A (Betacarotene), Vitamin S C, E, zinc and copper.
A more recent AREDS 2 study has found a beneficial effect from lutein, xeanthin, lower doses of zinc, and no betacarotene. The addition of Omega-3 fatty acids in AREDS 2 did not show a beneficial effect in reducing the progression of advanced AMD.
It is important to remember that dietary intake of these antioxidants provides better bioavailability than oral supplements, and only the group who had low dietary intake of lutein/zeaxanthin showed a reduced rate of progression to advanced AMD using AREDS2.
Food sources rich in these antioxidants include dark green leafy vegetables, fish (i.e. mackeral, salmon sardines), nuts (pistachios, walnuts, almonds) and fruits.
AREDS supplements may reduce the progression to advanced dry macular degeneration in approximately 25 to 30 percent of patients who have high risk macular degeneration.
A discussion with your retinal specialist and primary eye care physician should be undertaken before initiating these supplements, because individuals with mild AMD or no AMD do not show a benefit from these supplements. Nonetheless, a healthy diet provides general eye and health benefits.
Can AMD be treated?
Currently there is no treatment to reverse or "cure" dry macular degeneration. However, research continues to identify genetic markers and trials are underway to test whether progression of the dry form of macular degeneration can be treated with pharmacological agents.
With respect to the "wet" form of macular degeneration, treatment consist of pharmacological agents called Anti-VEGF agents, which are administered as intraocular shots to stop the abnormal growth of vessels under the retina and leakage of fluid which is responsible for distorted and/or blurred central vision.
Research continues to find longer acting agents and methods of treatment to reduce the need for monthly or bimonthly injections associated with wet AMD. This is an exciting era in research related to addressing sight-threatening diseases and potential surgical procedures such as artificial vision and gene therapies for individuals with severe vision loss from optic nerve and retinal diseases.
With more than 18 years of experience, Dr. Nancy Bonachea specializes in diseases and surgery of the retina including macular degeneration and diabetic eye disease, as well as macular, retinal tear and detachment surgery. She is currently Chief of Ophthalmology, Elliot Hospital, and Retinal Specialist for CMC Special Care Nursery.