Questions answered in this video include:

1. What is age-related macular degeneration (AMD)?
2. What is the typical progression of AMD?
3. What are the risk factors for developing AMD?
4. Is exposure to UV rays a risk factor?
5. What can we do to help prevent macular degeneration?
6. Does lutein help to protect us against AMD?
7. What symptoms do patients with AMD experience?
8. At what age do symptoms usually start to show?
9. How is macular degeneration diagnosed?
10. Where do ophthalmologists look for drusen?
11. What treatment options are available for macular degeneration?
12. Are there any medical or surgical therapies for AMD?

Notes on Dr. Tennant:

This interview is with Dr. Matthew Tennant, MD, FRCSC, Dip ABO, a retinal eye surgeon in Edmonton Alberta. After completing his medical degree at the University of British Columbia and ophthalmological training at the University of Alberta, Dr. Tennant completed a 2 year vitreoretinal fellowship at the prestigious Wills Eye Hospital in Philadelphia. Dr. Tennant’s numerous research interests include tele-ophthalmology and diabetic retinopathy, and he has received numerous awards throughout his career, acknowledging his many academic and research accomplishments. He is currently a clinical professor and residency program director with the Department of Ophthalmology at the University of Alberta.

You can visit Dr. Tennant’s website at: http://www.alberta-retina.com/ for more information on AMD and other eye conditions.

Overview:

Age related macular degeneration (AMD) is a common disease where a loss of clear vision occurs at the center of the field of view, often found in older individuals. This disease affects an area of the retina known as the macula, which responsible for forming clear, sharp images. This loss of sharp vision makes common tasks such as reading and driving difficult.

There are two types of age related macular degeneration, wet and dry. Wet AMD, the more severe form of the two, is when abnormal growth of blood vessels happens underneath the macula; dry AMD, on the other hand, is when the light sensitive cells of the macula degenerate, which often involves a slower, more indolent clinical course. Age related macular degeneration is a leading factor in vision loss in elderly individuals over 60 years of age, and can be caused by a large variety of genetic, environmental, and lifestyle factors.

Pathophysiology:

Wet AMD is due to abnormal blood vessel growth beneath the macula. Due to their delicate nature, these blood vessels may leak fluid below the macula, lifting the macula from its normal position. Wet AMD is considered to be an advanced AMD stage as soon as it appears, and can cause rapid damage to the patient’s vision. This type of age related macular degeneration makes up two-third of all advanced AMD patients, though it only accounts for a minority of cases if both intermediate and advanced stages are considered.

The most common symptom for wet AMD is having a straight line appear as though it were crooked; this is due to the lifting of the macula, which distorts the image projected onto it. Also, a small blind spot at the center of field of view may also be present.

Dry AMD results from a loss of light sensitive cells in the retina; the progress of the degeneration can be slow enough to be unnoticeable. But over time, it can progress to the degree that central vision is completely lost. Dry AMD directly leads to blurred vision, which can make recognizing faces, reading, driving, and other tasks difficult. It has been observed that both eyes are generally affected in dry AMD patients, but the severity of the degeneration can vary greatly between the two eyes.

Early symptoms of dry AMD include blurred vision, lower contrast sensitivity, and drusen, which are characteristic yellow deposits of extracellular material which accumulate under the retina. Drusen can only be detected by a comprehensive dilated eye exam. However, in isolation they are rarely a cause of vision loss, and researchers are yet to determine the exact relationship between druse and AMD.

Dry AMD can be further categorized into three stages: early, intermediate, and advanced dry AMD. In the early stage vision loss is minimal, and is accompanied by minor presence of druse. The intermediate stage normally has many drusen or a few large ones, and vision loss at the center of the visual field can be observed. The advanced stage happens when light sensitive cells start to breakdown.

Many factors can raise the risk of age related macular degeneration, including smoking, obesity, race, genetics, hypertension, and exposure of the eye to UV rays. Race-wise, it has been noted that white populations are more prone to vision loss caused by AMD than African American populations. Genetics also plays an important role in the development of AMD, with over half a dozen genes discovered to be highly related to this disease. It has also been observed that those having a close relative with AMD are also at higher risk for developing the disease. As well, females appear to have a greater risk than males. Finally, healthy lifestyle choices such as eating a diet rich in vegetables and fish, exercising regularly, maintaining an adequate body weight and blood pressure, and not smoking and/or smoking cessation can help reduce the risk of developing age related macular degeneration.

Treatment:

Dry AMD has no effective treatment once it has reached the advanced stage. However, during early and intermediate stages, specific mixtures of antioxidants and zinc have been observed to greatly reduce the progress of dry AMD.

Wet AMD, on the other hand, can be treated with injections, laser surgery, and photodynamic therapy. The injections method, as the names suggests, involves injecting a type of chemical known as anti-VEGF into the eye. This chemical discourages the growth of blood vessels and is proven to be very effective in halting the progress of the AMD, sometimes even resulting in improved vision. However, since the effect of this chemical wears off with time, regular treatments are required.

Laser surgery uses a laser to destroy leaky blood vessels under the macula, preventing further vision loss. However, laser surgery may destroy surrounding tissues and some vision as well. Only a small portion of wet AMD patients are suitable for this treatment, and it is more effective when the blood vessel growth is further away from the fovea.

Photodynamic therapy involves injecting a light-sensitive drug called verteporfin into the patient. Since it tends to stick to new blood vessels, it preferentially binds to new blood vessels in the macula. When a light is shone into the eye for a short period of time, the drug becomes activated and destroys the blood vessels. This method does not destroy the surrounding tissue, and can effectively halt the progression of AMD. However, due to the nature of the drug, patient must avoid exposure to bright light such as sun light for five days after treatment.

Research:

Currently, research is being done at the National Eye Institute in the U.S. researching the possibility of transplanting healthy cells to the affected areas of the macula. As well, various anti-inflammatory treatments for wet AMD are currently being investigated.

References:

Medscape Reference:

http://emedicine.medscape.com/article/1940442-overview#showall

National Eye Institute:

http://www.nei.nih.gov/health/maculardegen/armd_facts.asp