Macular degeneration: What is an AMD?
Age-related macular degeneration – or AMD for short – is one of the most common eye diseases in Germany. There are around five to six million people affected by this retinal disease. AMD is one of the causes that can lead to blindness in the elderly.
AMD comes in two different forms:
- In dry AMD, cells in the retina gradually die. AMD cannot be cured and there is currently no effective therapy for the dry form of AMD.
- In wet AMD, blood vessels grow into the retina and destroy central vision as the disease progresses. The wet form and the ingrowth of blood vessels into the retina can be treated by injection therapy and be slowed down the use of growth inhibitor drugs .
The macula – the affected area in the disease
The macula is an anatomical structure at the central retinal location and a crucial location on the retina. The most important information received by the eye is perceived through this point. In the macular degeneration, it is precisely this point that is affected.
Age-related macular degeneration is a type of chronic metabolic disease in which the metabolic transport of nutrients between the retina and the choroid no longer functions properly.
Metabolic transport between retina and choroid disrupted
Macular degeneration is a type of metabolic disease in which the metabolic transport between the retina and the choroid no longer works properly.
The choroid is the layer below the retina. The outer retinal layers and sensory cells – the so-called photoreceptors – are supplied by the choroid. The retina gets all the nutrients that this part of the retina needs to take care of itself and to process visual information.
Metabolic exchange no longer works properly
The metabolic end products that arise during vision must be broken down and transported away again through the choroid. This metabolic exchange between the retina and the choroid no longer works properly in macular degeneration.
As a result, over time – in advanced age -, metabolic end products collect below the retina. These deposits of metabolic end products under the retina can be seen as small yellow spots during the ophthalmological examination. They are called druses because of their similarity to rock inclusions. Over time, these druses increase in size and number and can affect the functioning of the retina.
Dry AMD disease
In the early stages of dry AMD, the so-called druses accumulate under the macula. As the process progresses, the druses become larger, increase and thus further restrict the flow of nutrients between the retina and the choroid. If the retina and thus also the macula are not supplied with necessary nutrients, the macula will progressively lose its function, and this will result in considerable impairment of cognitive vision.
In the late stage of dry AMD, visual cells are lost and so-called geographic atrophy occurs, which means the loss of visual fields directly in the central field of vision of the person affected. Dry AMD usually progresses slowly.
In 10-20% of patients, the so-called wet age-related macular degeneration develops from the dry form.
Wet AMD disease
The wet form of AMD occurs less often, but if left untreated it is also the more aggressive form of the disease.
The metabolic exchange between the retina and the choroid becomes so bad in the course of the disease that the retina begins to produce growth hormones and tries to form new vessels in order to be able to supply itself better. More nutrients should be drawn from the new vessels.
The newly formed, diseased vessels are leaky and cause fluid to accumulate and even bleed in the center of the retina. Macular edema develops. This severely restricts vision and leads to distorted vision and disturbances in the central field of vision.
If an ophthalmologist does not intervene quickly, this might lead to complete blindness. With prompt examination by the ophthalmologist there are now various therapeutic approaches that slow or stop the progression of the disease.