Age-related macular degeneration, or AMD, is a disease affecting one’s central vision. It is the main cause for vision loss in the United States for individuals 50 years of age and older.
AMD may be categorized into two types: the wet form and the dry form. The majority of those affected by macular degeneration have dry AMD. Only about 10 percent of patients have wet macular degeneration, which is the more severe of the two types.
What is Wet Macular Degeneration?
An eye with wet macular degeneration will begin to form blood vessels under the macula from behind the retina. These abnormal and new blood vessels are very delicate and usually break. As a result, the blood vessels behind the eye hemorrhage blood as well as fluid,. From this excess of fluid, the macula is raised from its proper position in the middle of the retina. This causes severe and rapid damage to the macula.
One of the first few signs of wet macular degeneration is that one will begin to see straight lines as wavy.
What is Dry Macular Degeneration?
With dry macular degeneration, the light-sensitive cells found in the macula are progressively deteriorating. That is why the affects of AMD do not become apparent until later in life as early stages of dry AMD are slow moving.
As dry AMD advances, one will develop poor vision in the central field of sight. Objects within the center field of vision will begin to appear blurred or dimmed. Drusen are another symptom of dry AMD. Drusen are yellow to white in colour.
They are deposits found under the retina and while the exact correlation to dry AMD is not fully understood, it is known that the more drusen present in an eye, the greater the risk is for advanced dry AMD. Advanced dry AMD is the last stage of the disease and for which there is no cure.
- In total there are three stages of dry AMD:
- Early dry macular degeneration
- Intermediate dry macular degeneration
- Advanced dry macular degeneration
- Early Dry AMD
During the early stages of dry AMD, any loss of vision has not yet occurred. Drusen will be present in an eye with early dry AMD, however, the drusen will either be small in size but high in number, or medium-sized but low in number.
Intermediate Dry Age-Related Macular Degeneration
At this stage of dry AMD, a patient may notice some changes to vision such as a blurred central vision, or the need for more light to see or read. With intermediate dry AMD, drusen are several in number as well as medium in size, or there are few but very large drusen present.
Advanced Dry AMD
With advanced dry macular degeneration, drusen are not only present in the eye, but the structure of the macula and retina begin to break down. Again, one will experience a blurred or dimmed center field of vision that may grow bigger and / or darker over time.
It is important to highlight that individuals with dry AMD in only one eye may not notice the symptoms or any impact to their vision until the other eye is also affected. With one healthy eye, an individual may still be able to see clearly in their center field. The best solution to detect the disease and prevent it from progressing is to make sure regular eye exams and dilated eye exams are scheduled.