ICD codes for this disease: ICD codes are internationally valid medical diagnosis codes. They are found e.g. in medical reports or on incapacity certificates. H35
"Smoking is one of the biggest risk factors for macular degeneration, so protect yourself from blindness by stopping smoking!"Dr. med. Mira SeidelArticle overviewMaculum generation
- Causes and risk factors
- Examinations and diagnosis
- Disease course and prognosis
Macular degeneration: description
The retina is a special part of the nervous system that lines most of the inside of the eyeball. It is responsible for converting light stimuli into nerve impulses: The light strikes certain molecules in the photocells of the retina, which generates the nerve impulses. These impulses are in turn directed by the optic nerve to the brain, where they are processed and finally recognized as images.
The retina construction and its function
The retina consists of many layers that are formed by different types of nerve cells. The first link in the processing of light signals to nerve impulses are the light-sensory cells, the so-called cones and rods. They convert the light stimuli and pass them on to other nerve cells, which in turn are connected to other cells. In this way, the signal is transported via several intermediate stations to the optic nerve and from there to the brain.
The light-sensory cells are located in the deepest layer of the retina, so that the light must first pass through all other layers. When the light has arrived there, a certain cell component, the retinal, changes and splits off small parts ("membrane discs"). It is consumed and must be renewed.
Disturbed waste removal
This reprocessing of the photoreceptor cells is the responsibility of the associated retinal pigment epithelium (RPE). It transports the resulting waste products and regenerates the cones and rods.
If this degradation component is damaged, accumulating metabolic products in the retina, for example, the lipofuscin and split membrane discs can no longer be properly removed. They pile up and destroy the RPE first. As a result, the photoreceptor cells also perish and macular degeneration occurs.
What happens with macular degeneration?
Although the macular degeneration is a disease of the retina, it is not the entire retina damaged, but mainly a specific area. The area is called macula lutea or "yellow spot". This is a roundish, approximately five millimeters large area in the center of the retina, which stands out from its environment by a special density of light sensory cells.
The light-sensory cells of the macula are predominantly cones that allow sharp vision in color. The other group of light-sensing cells (photoreceptors) represent the rods. They are responsible for the black-and-white vision in low light conditions and therefore important above all in dim light or at night. Without the yellow spot, one would not be able to read, recognize faces, and only dimly perceive the environment.
If the macula is destroyed, it results in a massive visual impairment. Since the retina around the yellow spot often remains intact, one does not completely blind in this disease. Accordingly, in the macular degeneration, the edges of the field of view are still perceived, but not what is fixed in the center of the visual field.
Which forms of macular degeneration are there?
A distinction is made between the age-related macular degeneration of those in which gene defects or other factors are the cause. In addition, a distinction is made between wet and dry macular degeneration.
Age-related macular degeneration (AMD)
The most common form is called age-related or age-related macular degeneration. The destruction of the yellow spot rarely begins before the age of 60.
Overall, this disease is the leading cause of blindness in western industrialized countries. In Germany alone, about 4.5 million people are affected. The term "blindness" may be misleading, because even a low vision is maintained. In the later stage of the disease, one can almost speak of blindness.
In poorer countries, age-related macular degeneration is often not the first cause of blindness because of the dominance of other eye diseases that can not be treated adequately due to lack of medical care. Examples are the green star (glaucoma) or infectious diseases like the trachoma.
The dry macular degeneration
75 percent of patients with age-related macular degeneration are known as dry macular degeneration. The insufficiently transported away waste products of the photoreceptors and especially lipofuscin are deposited and form in some places larger associations, which are called "drusen".
Drusen-induced extensive damage to the retinal pigment epithelium is also known as "geographic atrophy". As dry macular degeneration progresses slowly, it initially has little effect on vision. However, it can change into a wet macular degeneration at any time.
The wet macular degeneration
The wet macular degeneration (exudative form) is almost always the result of a dry macular degeneration. The pathological deposits in the retina lead to the destruction of the cells of the retinal pigment epithelium and create gaps in the membranes under the retinal layer. In addition, the blood supply is disturbed by the choroid and the retina at the affected sites are no longer sufficiently supplied with oxygen.
Vessels destroy the retina
The body therefore forms certain messenger substances, so-called growth factors, which stimulate the regeneration of small blood vessels. These factors also play an important role in macular degeneration treatment. Their action sprouts small vessels from the choroid. The process is called choroidal neovascularization (CNV).
Although the body thus wants to counteract the oxygen deficiency, the new vessels also grow through the membrane gaps under the retina, where they actually do not belong. As a result, the retina may detach, leading to impaired vision and eventually partial or even total blindness. In addition, the walls of the newly formed vessels are not as stable as the normal blood vessels. Therefore, a little bit of fluid constantly leaks into the environment, which further promotes retinal detachment. This phenomenon also explains the term "wet macular degeneration". The small vessels can also tear, bleeding into the retina.
The wet macular degeneration is much faster and more dangerous than the dry form. It is estimated that about every seventh dry macular degeneration eventually passes into a damp.To the table of contents
Macular degeneration: symptoms
The macula is the most important area of the retina for seeing, if you fix something sharply, it is only possible through the yellow spot. In the peripheral areas of the visual field, the environment is only dimly perceived. But even the blurred vision of the edges around the macula is important. Only in this way can one orientate oneself in space and register movements around oneself.