Today while I was under the hairdryer I read an article about Dame Judi Dench who is living with Age-Related Macular Degeneration, a medical condition which usually affects older adults and results in a loss of vision in the center of the visual field (the macula) because of damage to the retina. It occurs in “dry” and “wet” forms. It is a major cause of blindness and visual impairment in older adults (>50 years). Macular degeneration can make it difficult or impossible to read or recognize faces, although enough peripheral vision remains to allow other activities of daily life.
What are the risk factors?
Age – The number one risk factor is age. One third of adults over the age of 75 are affected by age-related macular degeneration.
- Smoking – Smoking increases an individual’s chances of developing age-related macular degeneration by two to five-fold. The retina has a high rate of oxygen consumption. Anything that affects the rate of oxygen delivery to the retina has the potential to negatively impact vision. Smoking causes oxidative damage, which is thought to contribute to the development and progression of this disease.
- Family history of macular degeneration – An individual is more likely to be affected by age-related macular degeneration if someone in his or her immediate family has been affected.
- Gender – Females are more likely to be affected by age-related macular degeneration than males. This may be due to the fact that females live longer than males, and thus have more time to develop the disease.
- Race – Caucasians are more likely to be affected by age-related macular degeneration than other races. This may be due to differences in genetic background or pigmentation.
- Prolonged sun exposure – Ultra-violet (UV) light damages retinal tissue directly, and can also lead to the accumulation of products that are harmful to the retina.
- A high fat diet, and/or one that is low in nutrients and antioxidants – Individuals with diets high in fat, cholesterol and sugar, and low in antioxidants are more likely to be affected by age-related macular degeneration.
- Obesity – Overweight individuals are more likely to be affected by age-related macular degeneration. An individual with a body mass index (BMI is a measure of body fat) of greater than 30 is 2.5 times more likely to be affected by age-related macular degeneration.
- High blood pressure – Individuals with high blood pressure are more likely to be affected by age-related macular degeneration. High blood pressure, like smoking, leads to a constriction, or narrowing, of the blood vessels that nourish the retina, negatively affecting its health.
- Eye color – Individuals with light-colored eyes are more likely to be affected by dry age-related macular degeneration. This may be due to the fact that light-pigmented eyes offer less protection from damaging UV light.
- Inactivity – Individuals who do not follow a regular exercise routine are more likely to be affected by age-related macular degeneration. In dry age-related macular degeneration, the retina does not receive adequate oxygen, leading to the death of cells in the macula. It is known that exercise improves cardiovascular health, and might prevent an individual from developing this disease.
- The presence of macular degeneration in one eye – If an individual has macular degeneration in one eye, he or she is more likely to develop it in the other eye.
Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. The blood and fluid raise the macula from its normal place at the back of the eye. Damage to the macula occurs rapidly.
With wet AMD, loss of central vision can occur quickly. Wet AMD is also known as advanced AMD. It does not have stages like dry AMD.
An early symptom of wet AMD is that straight lines appear wavy. If you notice this condition or other changes to your vision, contact your eye care professional at once. You need a comprehensive dilated eye exam.
Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred spot in the center of your vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye.
The most common symptom of dry AMD is slightly blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks. Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected.
One of the most common early signs of dry AMD is drusen. Drusen are yellow deposits under the retina. They often are found in people over age 60. Your eye care professional can detect drusen during a comprehensive dilated eye exam.
Drusen alone do not usually cause vision loss. In fact, scientists are unclear about the connection between drusen and AMD. They do know that an increase in the size or number of drusen raises a person’s risk of developing either advanced dry AMD or wet AMD. These changes can cause serious vision loss.
Dry AMD has three stages, all of which may occur in one or both eyes:
- Early AMD. People with early AMD have either several small drusen or a few medium-sized drusen. At this stage, there are no symptoms and no vision loss.
- Intermediate AMD. People with intermediate AMD have either many medium-sized drusen or one or more large drusen. Some people see a blurred spot in the center of their vision. More light may be needed for reading and other tasks.
- Advanced Dry AMD. In addition to drusen, people with advanced dry AMD have a breakdown of light-sensitive cells and supporting tissue in the central retinal area. This breakdown can cause a blurred spot in the center of your vision. Over time, the blurred spot may get bigger and darker, taking more of your central vision. You may have difficulty reading or recognizing faces until they are very close to you.
Symptoms of age-related macular degeneration include the following:
- Blurred or decreased central close-up and distance vision, which is often delayed because patients subconsciously ignore the eye with worst vision prior to development of the condition in the previously good eye.
- Blind spots, or scotomas, are a direct result of lost macular function.
- Straight lines look irregular or bent, called metamorphopsia, and objects appear a different color or shape in each of the eyes.
- Objects appearing smaller in one eye than the other, called micropsia, may also indicate a swelling and bulging of the macula, leading to a greater distance between the individual photoreceptors, which in turn causes the brain to interpret the object as smaller than seen by the good eye.
- 18 years to 60 years: every 2 years
- 61+ years: every year
- Those who wear glasses or contacts: every year
Sources: http://www.ahaf.org/macular/?gclid=CKjVmNit064CFcbsKgodoCBCgQ; http://www.ahaf.org/macular/about/risk.html?gclid=CPPu2YCu064CFYZoKgod8RFjfA; http://en.wikipedia.org/wiki/Macular_degeneration#Signs_and_symptoms; http://www.emedicinehealth.com/macular_degeneration/page3_em.htm; http://www.nei.nih.gov/health/maculardegen/armd_facts.asp#2c; http://www.cnib.ca/en/your-eyes/eye-conditions/amd/?gclid=CI-2sse3064CFU3UKgod_hwbdA; http://www.northcarolinahealth.com/