Dry macular degeneration: Causes, symptoms, and dry vs. wet AMD

By: Bel Marra Health | Eye Health | Thursday, July 06, 2017 - 06:30 AM

dry macular degenerationDry macular degeneration is a common eye disorder that requires early treatment if you want to avoid vision loss, but macular problems can also be classified as wet. So, here we take a look at dry vs. wet AMD (age-related macular degeneration).

Dry macular degeneration is an eye issue that tends to occur in people over the age of 65. It impacts the part of the retina (macula) that is responsible for clear vision in our direct line of sight. It can develop in one eye and then progress to both eyes. Dry age-related macular degeneration makes it difficult for some people to read, drive, and even recognize faces—however it does not necessarily mean that you lose your sight completely.

Dry macular degeneration is a chronic condition that can have a big impact on a person’s quality of life. Wet macular degeneration, which occurs when blood vessels grow beneath the retina, is less common.

How to understand macular degeneration?

Difficulty with vision can be attributed to many different things, but there are ways you can tell if AMD is at play. People might assume that dry macular degeneration means your eyes are literally dry, but the word dry refers to the type of macular problem and not the state of lubrication in your eyes. If a person suspects they have macular degeneration or has already been diagnosed, they should be monitoring their vision. This can be done several times a week with something called the Amsler Grid, or by using an object that has a pattern on it. A pattern of straight lines is helpful because, with wet macular degeneration, one of the first signs is a distortion of straight lines.

The Amsler Grid is a grid of horizontal and vertical lines with a dot in the center. It is held at a comfortable reading distance. One eye is covered while looking at the grid and then you switch and test the other eye. Changes in vision can be detected where the lines are no longer straight or absent. The earlier changes are detected, the more likely that treatment will be effective.

What causes dry macular degeneration?

While research into the cause of dry macular degeneration is ongoing, some evidence seems to point to a combination of hereditary and environmental factors, such as smoking and diet. Below is a list of common factors that could increase your risk of getting macular degeneration.

  • Age – the eye disorder is common in people over the age of 65
  • Genetics – researchers have identified several genes related to the development of the disorder
  • Race – it seems to be more common in Caucasians
  • Smoking – smoking cigarettes or being exposed to smoke can increase risk
  • Obesity – studies show that being obese can increase risk of early macular degeneration, which will progress to a more severe form of the eye condition
  • Cardiovascular disease – a link has been found between diseases that impact the heart and blood vessels and macular degeneration

There can be complications with dry macular degeneration. For instance, people with dry macular degeneration and central vision loss may also experience depression or visual hallucinations. Dry macular degeneration can also progress to wet macular degeneration.

Dry macular degeneration stages

There are three stages of dry macular degeneration. In the early stage of dry AMD, there is small yellow material that builds up in the retina. This is called drusen. Eye doctors can see this during an eye examination. At this stage, a person is not likely to have any reduced vision. However, in the intermediate stage, there tend to be more Drusen or irregular shaped Drusen, and people experience blurred vision. In the intermediate stage, some people find that objects appear distorted or a blind spot starts to develop. Advanced AMD is characterized by changes to the pigment in the retina. As well, the light-sensitive layer of the retina breaks down. Central vision can become distorted as a result of scarring. At the same time, central blind spots can be much larger, making it hard to read. People with this stage often begin to use more peripheral vision since central vision has been lost.

Symptoms of dry macular degeneration

Age-related macular degeneration can be painless when it is developing, so it is important to get regular eye exams. Being familiar with dry macular degeneration symptoms and not hesitating to seek medical attention if they develop can make the difference between clear vision versus a limited window to the world.

The following list covers many of the common dry macular degeneration symptoms:

  • Reduced central vision in one or both eyes
  • Visual distortions, including straight lines looking bent
  • Decreased ability adapting to low light
  • Increased blurriness
  • Difficulty seeing things at a distance
  • Difficulty recognizing faces
  • Difficulty distinguishing between colors that are similar
  • Decreased intensity of bright colors
  • Visual hallucinations, including flashes of light, color, and shapes
  • Presence of a blind spot in the central vision

Diagnosing dry macular degeneration

If you are experiencing any of the symptoms mentioned above, you should seek medical attention. Your doctor will diagnose your condition after considering your medical and family history and after conducting a thorough eye examination. You may undergo a variety of tests, including some that are listed below.

  • Back eye exam – a special instrument is used to examine the back of the eye. In this case, the doctor is looking for a blotchy or spotted appearance, which can be a sign of Drusen.
  • Center vision test – the eye doctor may use an Amsler Grid to test for problems in the center of your vision.
  • Fluorescein angiography – the doctor injects a colored dye into a vein in your arm and the dye travels to the eyes. It highlights blood vessels in the eyes. A special camera then takes pictures so the doctor can see if you have abnormal vessels or changes to your retina.
  • Indocyanine green angiography – this is an injected dye that is used to help identify specific types of macular degeneration.
  • Optical coherence tomography (OCT) – this is an imaging test, which shows a cross-section image of the retina in great detail. It is used to identify thinning or swelling of the retina.

Wet vs. dry macular degeneration

While both can impact vision, there is a difference between dry vs. wet AMD. The word “dry” is simply a classification of the disease.

Dry macular degeneration is diagnosed in close to 90 percent of cases and often occurs in both eyes. It is also known as “non-neovascular” since it does not involve the leakage of blood or serum, but can lead to deterioration of the retina. Wet macular degeneration, on the other hand, happens in about 10 percent of cases, but it results in 90 percent of the blindness that is linked to age-related macular degeneration. Wet AMD is caused by abnormal blood vessels growing behind the macula. When these vessels leak fluid into the retina, the macula bulges or lifts up, distorting central vision. Wet macular degeneration can lead to rapid vision loss.

It is important to know that about 10 percent of all age-related macular degeneration cases become wet AMD.

Dry macular degeneration progression

Dry macular degeneration progresses slowly. Many people don’t notice subtle changes in their vision at first. Over time though, they might become aware of gradual distortion or a decrease in their ability to read. When dry macular degeneration occurs near the center of the macula and spreads to involve the center, it can lead to dramatic changes in vision. There are often cases where the vision in one eye deteriorates much faster than the other eye. Researchers are hard at work, trying to find ways to prevent progression of the disease.

Currently, many eye specialists recommend a healthy lifestyle that includes proper nutrition and vitamin supplements to help promote good eye health. Unfortunately, there are no specific treatments for AMD. Various approaches, including laser treatments, transfusions, and injections to prevent progression from dry to wet macular degeneration have proved unsuccessful. Right now, close to two million Americans are suffering from age-related macular degeneration, but that number is expected to rise to three million by the year 2020. Today, there is a great deal of research being conducted around the world in the hopes of finding effective treatments.

Related: Home remedies to reverse age-related macular degeneration naturally


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Sources:

http://www.mayoclinic.org/diseases-conditions/dry-macular-degeneration/home/ovc-20164874
https://books.google.co.in/books?id=dI293mGVUMgC&pg=PT43&dq=dry+macular+degeneration&hl=en&sa=X&ved=0ahUKEwj51KX_6vHUAhVHto8KHYgfB_4Q6AEINTAD#v=onepage&q=dry%20macular%20degeneration&f=false
https://www.macular.org/dry-vs-wet-macular-degeneration
https://nei.nih.gov/eyedata/pbd4

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