Types of AMD

AMD develops gradually, moving from early to advanced stages. There are two types of AMD: dry and wet.

Dry AMD

About 90 per cent of AMD cases are classified as dry AMD. Usually, AMD starts as the dry type and can develop in one or both eyes. The process is slow and can advance over the course of several years. In fact, many people are unaware that they have AMD, since early dry AMD is usually mild or free of symptoms.

Dry AMD occurs when the layer of cells beneath the retina begins to age and thin. One of the most common early medical signs of dry AMD is the presence of small yellow-white deposits called drusen, which accumulate under the retina. These deposits may affect the overlying retina, particularly the light-sensitive cells in the macula. But the presence of drusen does not necessarily mean someone will develop AMD. In fact, many people over the age of 60 have a harmless type of drusen.

Dry AMD has three stages:

  • Early: In this stage, central vision is usually not affected. The eyes may have some small drusen, but there is a low risk (1.3 per cent) of progressing to advanced dry AMD.

  • Intermediate: In this stage, near and distance vision is affected, and a person may have a blind spot or blurring to some degree in the central vision. People with intermediate dry AMD are likely to have many medium-sized drusen, or one or more large drusen. After five years with intermediate dry AMD,the risk of progressing toward the advanced stage is 18 per cent. For people with large drusen in both eyes, the risk of developing advanced AMD is greater.

  • Advanced: At the advanced stage, the cells in the macula completely lose their ability to function. There is a definite blurred or blank spot in the centre of one’s sightline. Over time, vision will likely worsen and a person will have difficulty reading or recognizing faces. Up to 43 per cent of people in this stage of dry AMD will progress to wet AMD, the more aggressive form of the disease.

Wet AMD

Wet AMD is the most severe form of AMD and can cause a sudden loss of vision within weeks or months. Recognizing and then managing wet AMD early can help prevent further vision loss. That’s why it’s so important to speak with your eye doctor as soon as you notice a change in your vision.

Wet AMD involves the unexpected growth of abnormal blood vessels below the retina, which break into the macula, causing blood and fluid to leak. Cells in the macula become damaged, resulting in central blind spots and blurred vision. Once wet AMD is present in one eye, the chance of developing it in the other eye is greatly increased.

Two side by side images showing normal vision versus how vision can potentially be affected by AMD

Photos showing normal vision versus vision as it potentially can be affected by AMD, courtesy of the National Eye Institute.

CNIB partnered with Novartis Pharmaceuticals Inc. to raise awareness of the impact of AMD. The campaign, called "Worth a thousand words: Preserve your vision​," features this unique photo album of images that have been digitally altered to appear as they might be seen by someone living with AMD or diabetic macular edema (DME).​

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