Friday, July 15, 2016

Age-related macular degeneration




Definition
The macula is part of the retina with oval form, situated near its center, which is responsible for the sharp, central vision. Age-related macular degeneration is the most common causes for vision loss in people over age of 60. Macular degeneration, contrary to glaucoma, affects the central vision, which rarely results in complete blindness but seriously hardens people’s daily activities like reading, driving, recognizing faces, focusing different objects.
Forms
• Dry form: it is the more common form. It has slow evolution and rarely leads to complete vision loss. It is characterized by the formation of yellow deposits, called druses, in the macula. Such deposits could be found in many healthy people over age 60, but it is considered that the increase in their number is related to the development of macular degeneration. However, the exact role of the druses is yet unknown.
• Wet form: also named exudative or neovascular form. It is present in 15% of the patients with macular degeneration
. It can appear on the base of advanced macular degeneration or primary. In the second case, macular degeneration has faster development and more serious prognosis. Wet macular degeneration is characterized by the formation of abnormal and fragile blood vessels (a process known as neovascularization) . Their distortion leads to hemorrhages into the retina, which damages the central vision. Contrary to dry form, wet macular degeneration may lead to sudden and severe vision loss.
Risk factors
As causes for macular degeneration are still unclear, risk factors are to be revised and completed in the future. At the moment they include:
• Age- 10% of people aged between 66 and 74 years suffer from macular degeneration. This number jumps to 30% when talking about individuals aged over 80 years.  That’s because as with age sclerotic changes into the vessels grow, the blood supply of the macula is gradually being reduced, which causes slow atrophy of the cells.
• Smoking- smokers have twice as high risk for macular degeneration as non-smokers
• Family history of macular degeneration
• High blood pressure
• High cholesterol levels
• Race and phenotype- the condition affects more people from the white race and amongst them- those with lighter skin tone and eyes color
• Sex- more often in women 

Symptoms
In most of the cases macular degeneration has slow evolution. At the beginning the patients attribute the symptoms to over fatigue and do not look for medical assistance. In addition macular degeneration usually affects one of the eyes at the early stages, while the healthy one compensates the decreased vision. These are the reasons for the late diagnosis of the condition.
Symptoms of macular degeneration include:
• Blurred vision- one of the earliest signs could be the need of more light while reading or writing, or difficulty to focus the different words.
Diminished/ changed color perception- difficulty to differentiate colors, especially light colors from white colors or dark colors from dark colors
• Appearance of dark/white blind spots in the central visual field- outside of the spots, called scotomas, the vision is preserved
• Difficulty to see straight lines- the lines in the area of central vision appear wavy. Although this is a late symptom, it usually is the first one that bothers the patients enough to look for medical help
Diagnosis
Early diagnosis offers better chances to preserve the vision of the patient. In order to put the diagnosis macular degeneration, your doctor may perform some of the following tests:
• Amsler grid- a pattern that resembles a checkerboard with a dark square in its center. If the patient sees the straight lines as wavy, while watching the dark spot at the center of the grid, this could be a sign of macular degeneration
• Vision acuity test- to reject anomaly of refraction
• Ophthalmoscopy- a method that allows to see the macula and eventual presence of druses
• Fluorescein angiography- after injection of special contrast, the blood vessels in the eye are being visualized. This test allows to appreciate eventual neovascularization, which is characteristic for the wet form of macular degeneration
• Optic coherent tomography (OCT)- a special photograph that shows magnified image of the layers of the retina. Useful for early detection of macular degeneration, as well as for treatment evaluation
Treatment
No definitive treatment is available for macular degeneration. At the moment there are several treatment options:
• Antioxidants and vitamins like vit.C, E, zinc, copper, beta-carotene, to protect the retina and preserve the vision left
•Anti-angiogenic drugs- injected into the eye these medications slow down the formation of new blood vessels
• Laser therapy- in order to destroy newly formed blood vessels
• Photodynamic therapy- a photosensitive drug that selectively accumulates into the new vessels is injected into the blood stream. Than the drug, which is noxious for the vessels is activated with the help of a laser


Conclusion
As there is no specific prophylaxis for macular degeneration, the elimination of the risk factors, the healthy eating regime with lots of fruits and vegetables and the regulars eye check are the best steps a person could undertake to protect himself.


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