Macular Degeneration


Macular Degeneration
The term macular degeneration, a group of diseases of the human eye is summarized by the macula lutea ("the point of sharpest vision") - also called "yellow spot" called - involve the retina, accompanied by a gradual loss of function located there tissue.

Etiology and prevalence
Starting point for the sickness is not the nerve tissue of the retina, but its support structures, the retinal pigment epithelium, Bruch's membrane and choroid. With progressive disease is affected by the death of retinal cells in the central vision field. By far the most common form of macular degeneration is the age-related (or senile) macular degeneration (AMD), by definition, only after the 50th Age occurs. By changing age structure of the proportion of people who are affected by such disorders has increased significantly. The age-related macular degeneration is the leading cause of blindness in people over the age of 50 years in developed countries. It causes 32% of Neuerblindungen, followed by glaucoma and diabetic retinopathy by 16% of Neuerblindungen.

Worldwide, 25-30 million people are infected and about 500,000 new cases are added annually. In Germany, suffering from a form of macular degeneration, an estimated two million people in Austria are a total of 125,000 people affected.

Causes
Smoking is associated with the largest effect on the risk for future AMD, in addition to genetic predisposition and high blood pressure. Defects in the genes CFH, C3 and ARMS2 were confirmed in several studies as risk factors for the occurrence of AMD, but not for the further course of the disease.

Forms
Macular degeneration due to high myopia is known as myopic macular degeneration. There are genetic, so-called macular dystrophy, such as Best disease and Stargardt's disease, also called an "inverse" Retinitis pigmentosa is known to attack first the macula. Macular degeneration can also be toxic, as a result of Chloroquineinnahme occur, for example, for prophylaxis of malaria or rheumatism, and as a consequence of inflammation (so-called Presumed Ocular Histoplasmosis Syndrome, POHS).

The vast majority of patients but is of the age-related (or senile) macular degeneration (AMD) affected. The term "age" indicates the age down as the biggest risk factor besides smoking and genetic load. AMD is classified according to the Hamburg professor of ophthalmology Sautter in two forms: dry and the wet macular degeneration.

Dry macular degeneration
The dry (atrophic) form represents about 80% of cases, but only 50-10% of blindness caused by AMD. It begins by deposits of so-called drusen, metabolic end products (lipofuscin), and may in advanced stage in a flat cell death (geographic atrophy) pass the retinal pigment epithelium. Their progress is usually slow and insidious. Due to the frequent location below the point of sharpest vision but it can sometimes also lead to rapid loss of vision, and a protrusion of the visual cortex. This makes itself felt through distorted vision (metamorphopsia).

The dry form is no generally accepted treatment is known. It is discussed whether progression could be inhibited by administration of high doses of vitamins. A longer-term ingestion of such high doses of vitamins may increase the risk for certain cancers, so a careful Nutzen-/Risikoabw├Ągung should be done together with the treating physician. Recent studies such as AREDS for a possible preventive effect of the carotenoid lutein or WAFACS for a possible preventive effect of vitamin B complex (Vitamin B6 - pyridoxine, Vitamin B9 - Folic acid and vitamin B12 - Cyanocobalamin).

Wet macular degeneration
The dry may pass into the wet (exudative) macular degeneration, in which form under the retina flat vascular membranes (Choroidal neovascularization, CNV), which are prone to bleeding.

The occurrence of a distorted vision of the eye doctor should be consulted, as should be dealt with expeditiously. Report any losses can not be eliminated. In about 20 percent of cases are successfully treatable form in small blood vessels grow into the visual cortex. After a precise diagnosis by means of the optical coherence tomography Fluoreszenzangiografie and treatment can be started. In photodynamic therapy (PDT) is a substance photosensitising (verteporfin) is injected into the vein in your arm and exposed the place of the regenerated vascular membrane with a "cold" laser. This can often be a closure of the membrane can be achieved - deserted the new vessels - which is staying further Sehverfall.

Currently, new therapies with inhibitors of blood vessel growth, called anti-VEGF's (anti-Vascular Endothelial Growth Factor, German growth factor) inhibitors tested clinically. The currently most promising anti-VEGFs are ranibizumab (approval in the EU on January 24, 2007), Novartis and as a cheaper off-label bevacizumab treatment. In many patients it leads to a vision improvement. The aptamer pegaptanib since February 2006 in Germany for the treatment of age-related macular degeneration (AMD). It was developed with the aim to block highly specific and with high affinity to VEGF. This is possible too, but according to the results presented by different studies, the loss of sight "only slowed, not stopped. Other inhibitors of vascular growth are Corti statins.

Functional impact
The damage to the macula leads to

* Decrease in visual acuity, and thus the ability to read,
* Loss of contrast sensation,
* Loss of color vision,
* Decrease in the ability to adapt to changing light conditions (adaptation)
* Increasing the sensitivity to glare
* Central visual field defects.

Fixed the person an object, it is not possible to identify him clearly. The offender may see a clock but the clock does not recognize or see a conversation partner, not its features. Age of onset and severity of symptoms vary and depend on the form of the disease.

Since the disease is usually limited to the macula, is the external field and thus obtain the orientation ability of those affected. Even in darkness the parties involved are usually quite good, as the rods remain functional outside of the central retina.

macular degeneration are distinguished from the degeneration of the peripheral retina shares (for example, retinitis pigmentosa).

For the early diagnosis usually the Amsler grid test is applied.

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