Macular Degeneration

The number one cause of blindness and vision loss in the Western world past the age of 50 is age related macular degeneration. This condition is also known as ARMD or AMD. Since people within the specific age range are becoming tone of the population's largest percentages, macular degeneration has become a major problem that continues to grow.

Macular degeneration is just what is sounds like; the macula degenerating. The macula is a part of the retina and is responsible for the centrally sharp vision that is needed to do tasks such as reading and driving. Since AMD primarily affects the macula, the loss of central vision can occur. It typically causes distortion and blind spots that are directly in front of the visual field.

Dry and Wet Macular Degeneration

When a diagnosis of macular degeneration is made, it is either wet or dry. A wet diagnosis is known as neovascular while a dry diagnosis is known as non-neovascular. The term neovascular refers to new blood vessel growth in a specific area like the macular; these are areas in which there should not be any growths.

Dry macular degeneration is more common than wet macular degeneration. Approximately 90% of patients are diagnosed with a dry AMD. The disease in wet form typically leads to a more serious level of vision loss.

Dry Macular Degeneration/Non-Neovascular: The dry from of this eye disease is a beginning stage of AMD. It can be caused by the thinning and aging of the macular tissue which causes macular pigments, or a mixture of each of the processes.

When a yellow like spot or spots called drusen start to accumulate around and in the macula, this is dry macular degeneration. The theory is that these spots are debris or deposits from the deteriorating tissues. Slow central vision loss can occur with this disease, but it is generally not as serious as the symptoms of wet AMD. However, dry macular degeneration can progress slowly over a period of time; usually years. The late stage, geographic atrophy, gradually degredates the cells of the retina and cause severe loss of vision.

A study done by the National Eye Institute has announced that there is strong evidence that there are specific nutrients such as vitamins A, E and C, that might slow down or altogether prevent the progression of dry AMD. Their findings have led to the development of several kinds of AREDS nutritional formulas for preventing macular degeneration. The studies also show that by taking these formulas in high doses, the risk of early progression of AMD can be reduced by 25%.

In addition to possible preventative treatments, eye doctors further recommend that those with dry AMD wear specialized sunglasses that contain protective qualities against UV rays.

Wet Macular Degeneration/Neovascular: Out of all the dry AMD cases, approximately 10% will progress to a more damaging and advanced form of this eye disease. Under the retina, new blood vessels start to grow and leak fluid and blood. When this happens, the disease has progressed to wet macular degeneration. The leaking will cause permanent and irreversible damage to the light sensitive retina cells and they will die out, creating central vision blind spots.

CNV, also known as choroidal neovascularization, is the underlying issue that causes wet AMD and abnormal growth of blood vessels in order to supply more oxygen and nutrients to the retina. Rather, the process causes scarring to develop and this sometimes leads to severe loss of the central vision.

Wet AMD falls into two separate categories:

• Occult: This type of wet AMD is marked by the growth of new blood vessels under the retina that are not as pronounced. The leakage is not as evident in this from of wet macular degeneration, and this means that the loss of vision is less severe.
• Classic: In this type of wet AMD, the scarring and blood vessel growth have extremely clear outlines that are delineated just below the retina. In classic cases the risk for more sever loss of vision is ever present.

Signs and Symptoms

Age related macular degeneration typically produces loss of vision that is slow and painless. However, in rare instances, the loss of vision can come on suddenly. Early signs and symptoms of loss of vision due to AMD include the following:

• Shadowy looking areas in your central line of vision
• Unusually fuzzy vision
• Distorted vision

Using an Amsler grid, which is equal to viewing a chart full of blackened lines in the pattern of a graph, is one method of telling if you have this specific type of vision issue.

Often, eye care practitioners can detect the early signs of AMD before any typical symptoms present themselves. This is usually done by way of a retinal examination. When this eye disease is suspected, a short test that uses an Amsler grid to measure the central vision is done. If there is a central vision defect found, such as blurriness or distortion, the doctor might test by way of fluorescein angiography. This is a way to examine retinal blood vessels that surround the macula.

Common Causes

Although macular degeneration is connected with the aging process, it has been suggested by some researchers that there is also a genetic factor in play with this eye disease. Researchers at Duke University have been able to note a strong correlation between the development of age related macular degeneration and a genetic variant known as the H factor, or CFH. The deficiency of this gene is connected to nearly half of all cases of AMD.

Investigators from Columbia University Medical Centre have found variants of yet another gene known as complement factor B. This gene might also play a role in the development of macular degeneration.

Variants that are specific to both of the newly discovered genes, which seem to have a role in the immune responses of the human body, have been pinpointed in 74% of those who have been studied. In addition, variances of complement factor C3 have been connected with a higher risk of developing age related macular degeneration.

In December of 2003, it was reported by the Ophthalmology Clinics of North America that deteriorating cells that are starved for oxygen in the retina are quite likely to aid in the triggering of neovascularization and the damage that accompanies wet AMD. A protein known as vascular endothelial growth factor, or VEGF, is activated in cases of neovascularization. This is targeted in macular degeneration treatments though anti-VEGF medications.

Likely Candidates for Age-related Macular Degeneration

Aside from affecting people in the older population, AMD also occurs in Caucasians of all ages; particularly females. This disease may also be the result of medication side effects and seems to be genetically connected. In other words, ARMD may actually run in the family of those who are affected and have been diagnosed.

It is strongly suggested by recent evidence, that smoking ranks high on the short list for macular degeneration risk factors. Other factors for AMD include the following:

• Others in your family that have been affected by ARMD
• Lighter eye colour
• Obesity
• High blood pressure

Some research also points to too much sun exposure as a factor in the development of ARMD. However, this theory is not conclusively proven. Another theory is that high amounts of dietary fat may also be an AMD risk factor.

The following risk factors are fairly common for developing macular degeneration:

Aging: Loss of vision on significant levels is tied in with the advanced forms of age related macular degeneration. It increases from less than 1% of people in their 60's, to nearly 15% of those who are in their 90's. This data was garnered from the Canadian Medical Association Journal in February 2004.

Inactivity and Obesity: Those who have macular degeneration and are also overweight or inactive, have twice the amount of risk for developing advanced forms of AMD as compared to people who are at a normal body weight. This information was garnered from a study reported in Jun of 2003 in the Archives of Ophthalmology. This same study showed that people who partook in high level activities at least three times each week actually reduced the risk of advanced AMD development. This is compared to research done on people who were much less active.

Genetics: As already stated, there are recent studies that have shown variants of specific genes that are found in the majority of those who have AMD. Twin studies, both identical and fraternal, have also demonstrated that genetics are a factor in who does and does not develop AMD, and how severe it gets.

Hypertension/High Blood Pressure: As reported in Investigative Ophthalmology and Vision Science, a European study showed results that demonstrated that hypertension could possibly be connected to the development of macular degeneration. This study was printed in September of 2003.

Smoking: According to one British study, smoking definitely plays a major role in the risk for the development of AMD. Smoking was directly connected with approximately 25% of age related macular degeneration cases that caused a severe loss of vision. In the early part of 2006, The British Journal of Ophthalmology further reported that their findings showed that those who lived in the same home with a smoker are at double the risk of developing this eye disease.

Light Eye Colour: Since it has been long theorized that macular degeneration affects Caucasian people more than other populations, (especially those who have light skin and eye colour) some studies suggest that since darker eyes contain more pigment, the pigment serves as a protective factor against developing AMD due to over exposure to the sun. There is yet to be any conclusive evidence to support this theory but researchers are looking into it more.

A smaller study that was reported on by the British Journal of Ophthalmology in January of 2006 was not able to find any connection between sun exposure and AMD. In fact, this same research study found zero relation between AMD and lighter eye or hair or skin colour. Earlier research that found lighter eyes and skin are in fact connected with greater risk for AMD contradicts the above findings.

Side Effects of Medications: In some macular degeneration cases, there seems to be an increased risk from side effects of certain toxic medications, such as the following:

1. Stelazine
2. Trilafon
3. Thorazine
4. Aralen
5. Phenothiazine

It is noted in the findings of the American Academy of Ophthalmology, risk factors of AMD have proven to be contradictory depending on the research and studies. The only consistent risk factors of AMD are smoking and aging.

Treatments and Methods

Currently there are no outright cures for age related macular degeneration. However, there are a few treatments that may be able to improve vision quality, or even delay the diseases progression.

Macular degeneration treatments depend on what stage the disease is in. There are no treatments for dry AMD that have been approved in Australia as of yet. However, wet AMD can be slowed or prevented through nutritional intervention.

For wet AMD, available treatments are aimed at halting the growth of abnormal blood vessels. There are approved FDA medications for this form of the eye disease. They include these drugs:

• Eylea
• Lucentis
• Macugen
• Visudyne
• Photodynamic Therapy (PDT)

A significant amount of people suffering from wet macular degeneration have shown improvement from using Lucentis.

Nutrition and Macular Degeneration

Many eye care professionals and researchers believe that specific types of nutrients, such as lutein, zinc, zeaxanthin, and vitamins E, C and A, can help to lower the risk for developing AMD, or at the very least, slow the progression of dry AMD. High levels and zinc and antioxidants for slowing or halting development of macular degeneration have been heavily reported on based on results shown in 2001 by the Age-Related Eye Disease Study. The Age Related Eye Disease Study showed these results and the research was done by the National Eye Institute.

Part two of the Age Related Eye Disease Study started late in the year 2005 to figure out if similar protective affects against age related macular degeneration may be connected to other types of nutrients such as Lutein, omega 3 fatty acids and zeaxanthin, which is found in leafy green vegetables.

Findings in the August 2001 edition of the Archives of Ophthalmology show that by consuming omega 3 fatty acids proved to provide a protective effect against advanced macular degeneration. On the other hand, consuming omega 6 fatty acids, which is found in vegetable oils, was connected with a higher risk for development of AMD.

Testing and Low Vision Devices for Treatment

Even though there has been significant progress towards treatment and research of macular degeneration, experiencing a total recovery of lost vision due to this eye disease remains unlikely. Your eye care specialist may want to regularly check your vision using the Amsler grid which is mentioned above. Testing each eye separately with this grid helps to better monitor vision loss. The Amsler grid is a highly sensitive testing method and it can detect problems with central vision before the doctor sees any age related macular degeneration damage during routine eye examinations.

For people who have experienced loss of vision due to AMD, there are several low vision devices that are available to aid in mobility and other tasks that are visually specific.