Macular Degeneration

Age Related Macular Degeneration is a condition that cause the loss of visual acuity in a person’s central vision.  There are two types of macular Degeneration, wet and dry, and both have the same debilitative effect on the central vision of an affected person. The risk of developing macular degeneration increases rapidly beyond the age of 50, but there are many factors both controllable and otherwise that can dramatically change the likely hood of developing the disease.

Article Contents:

  • Types
    • Wet
    • Dry
  • Causes
  • Symptoms
  • Detection
  • Treatments 

Macular Degeneration: Types

The macular is the central part of the rear layer of the eye known as the retina. Light is focused through the cornea, iris, and lens onto the retina which captures and converts the light into signals to send to the brain through a network of thousands of tiny nerves. Right behind the retina is the Choroid, which supplies blood to the retina and is also integral to the process of macular degenertion. While the macula only represents as little as 3% of the surface area of the retina, because it interprets central vision it is responsible for nearly 50% of the visual information sent to the brain.

Wet Macular Degeneration

Wet macular degeneration (also known as exudative or neovascular AMD) is caused by blood vessels growing up from the choroid into the retina, a process that is normally subdued by the retinal pigment epithelium cells. The leakage of blood and proteins eventually causes permanent damage to the photo-receptors on the retina and without treatment. Left untreated, this process will cause central vision to decay rapidly.

Due to the rapid onset and permanent damage caused, wet macular degeneration is considered more severe than dry macular degeneration. In fact whilst only 10% of macular degeneration sufferers have this form of the disease, they account for 90% of people who are blinded as a result. It should be noted that macular degeneration does not cause complete blindness, but without central vision simple tasks such as reading become completely impossible.

Until recently there were no treatments available, but fortunately modern science has been able to discover a way to disrupt the growth of the blood vessels, helping to stall the decay of vision. There are at least 4 treatment options available or in development that involve varying levels of risk and success, you can read about them on the macular degeneration treatments page.

Dry Macular Degeneration

Loss of vision through dry macular degeneration happens as a result of cells in the pigment epithelial layer (below the retina) dying. When these cells die, the photo receptor cells (rods and cones) above them on the retina also die leaving blank spots in an affected person’s vision. Around 90% of macular degeneration sufferers have this form of the disease.

While there is currently no cure, the advancement of dry macular degeneration is relatively slow and the National Eye Institute has suggested that vitamins with high quantities of the antioxidants lutein and zeaxanthin can further slow it’s progression. An Australian study is also suggesting that laser therapy could be used to eliminate the buildup of drusen (fatty deposits of dead cells, an early sign of macular degeneration) on the retina in an attempt to slow or even halt the onset of dry macular degeneration.

Causes of Macular Degeneration

Whilst macular degeneration is largely regarded to be age related given the high correlation between older age and increased presence of the condition, there are many factors that can dramatically increase the chances of contracting this debilitating disease.

  • Aging: Approximately 10% of people aged 66-74, and 30% of people aged 75-85 have macular degeneration. While various studies report dramatically different figures, the upward trend with age is always present.
  • Obesity, Fat intake, high blood pressure and general cardiovascular health all have been found to demonstrate an increased risk of contracting macular degeneration
  • Smoking increases the risk of contracting macular degeneration by 2 to 3 times. Quitting smoking is the best controllable way to reduce the risk of getting macular degeneration, studies have shown that chemicals in tobacco have toxic side effects on the retina.
  • Exposure to sunlight is a controversial issue, some studies have shown no correlation, where others have shown strong correlation. Regardless, exposing the eye to UV rays is proven to increase the risk of contracting many other vision debilitating eye conditions and sun-glasses should always be worn outdoors.
  • Ethnicity studies have shown that Caucasians are more susceptible than people of African heritage.
  • Genetic inheritance plays a large part in the risk of contracting macular degeneration. The odds of contracting the disease jump from around 12% to 50% for those with a relative that has macular degeneration.

Symptoms of Macular Degeneration

As macular degeneration directly affects central vision, the early signs often include:

  • Blurred vision
  • Shadowed vision 
  • Fuzziness.

 As the condition progresses, other symptoms may include:

  • Lower responsiveness to a change from bright light to a darker room.
  • Trouble separating dark colors from other dark colors, and light colors from other light colors
  • Distorted vision – the Amsler test below is a common example where the lines of the grid may appear warped or even missing in parts.

The onset of all of these symptoms can be very slow, as seen with dry macular degeneration, or extremely fast with wet macular degeneration. Because the damage this disease causes can often become permanent it is extremely important visit an eye care professional immediately apon any loss of visual acuity. The sooner the condition is identified the more effectively it can be handled. These symptoms are all discussed in further detail on our macular degeneration symptoms page.

Macular Degeneration Tests & Detection

The Amsler grid, as picutred to the right, is a common self-diagnosis tool and a full size grid along with usage instructions can be found right here on our macular degeneration testpage. The amsler grid is simply a grid with a dot in the middle to provide a point of focus. If a user is unable to see the dot in the center, or the lines of the grid appear warped or distorted, it is definitely book an appointment with an eye doctor for a proper retinal examination.

Nowadays most eye doctors will use optical coherence tomography (OCT) for both diagnosis and monitoring of macular degeneration. OCT is a process that captures extremely fine detail 3D images from within biological tissue by shooting long wavelength light (allowing better penetration) into the tissue. This technology is perfect detecting issues in the eyeball on and between the retina and choroid where macular degeneration develops.

Macular Degeneration Treatments

Whilst there is no way to cure age related macular degeneration, there are some treatments now available that can help to suspend or at least slow the onset of the condition.

The sooner the condition is identified the more likely that it can be handled successfully. Dry macular degeneration has no known cure, but at least one study has shown that if discovered early enough – a dietary change or vitamin supplement including  the antioxidants lutein and zeaxanthin can slow progression. Unfortunately the validity of this study is questionable considering it was sponsored by the company that manufactured the supplements used in the study, and there have been other studies made which found similar products to have no noticeable effect.

There are now some approved treatments for wet macular degeneration. They can work to stop the progression of the disease, but involve injections directly into the retina on a fortnightly or monthly basis and cannot undo any permanent damage doneas a result of leaving the disease unchecked too long.

Follow this link for a full rundown on the current macular denegeration treatments.