Age-related macular degeneration is the most common cause of blindness in the elderly population, but it could be prevented. Let us find out how...
The eye is a delicate yet the most important part of our human body. However, we encounter different eye problems like unable to see things at a distance or nearby objects. Even as we age, we undergo several eye related issues. Age-related macular degeneration is the most common cause of blindness in the elderly population, but it could be prevented. Let us find out how...
The BBSRC reported on January 4, 2010, that scientists at University College London have discovered that the relationship between two blood proteins has a main role in preventing the onset of Age-related macular degeneration. In a paper to be published in the American Journal of Biological Chemistry, January 8, 2010, the UK research team presented their new findings on how the interaction of blood proteins work to promote or hinder the development of AMD.
What is Chronic Degenerative Condition?
AMD is the single most common cause of eye disease in the world's elderly population. Around 15 million cases in the US alone and many millions more throughout the world suffers from this condition. The disease attacks the macula which is the centre of the eye where the sharpest vision takes place, and leaves the victim with blurred or pitted vision or dark holes in sight.
This is caused by the breakdown of retinal cells that can lead to 'dry' AMD, or the more serious 'wet' form. The latter affects only about 10 per cent of all AMD sufferers, but is the most common cause of the majority of cases of blindness.
In the wet form of AMD, the membrane underneath the retina thickens and then dislodges. This results in a disruption of the oxygen supply to the macula, which in turn leads the body to compensate by growing new, abnormal blood vessels. These blood vessels begin to grow and push up from beneath the membrane through the cracks behind the retina and head towards the macula. The retina will often appear raised. Damage to the macula results in central vision loss, which can happen very quickly. Once lost it is irreparable.
New Insight Helps Fight Disease
The UCL research team have studied the way in which a common blood protein which is present in the degenerative process, pulls in another related blood protein. It is this other blood protein that provides the key to serious eye damage. In the presence of inflammation, its production increases at a vast rate and this causes macular deterioration.
It is believed that both forms start on a common molecular route and then deviate into wet or dry AMD. An early indicator of the condition, are the yellowish deposits or drusen that is usually discovered by an ophthalmologist. By studying this material, the team were able to isolate two blood proteins involved in its formation - blood protein factor H, and a second known as C-reactive protein.
During the normal aging process, the eye will naturally lose cells and this is offset by the blood supply thereby bringing C-reactive protein at a low level of activity to assist in the routine clearing away of dead cells through mild inflammation.
However, in conditions of high inflammation, the levels of C-reactive protein will increase drastically. This sets up a vicious circle in which uncontrolled C-reactive protein causes damage to the retina, which is followed by more inflammation and then more retinal damage, and so on. It is the debris resulting from this process which is known as drusen.
The team also discovered that a genetically different form of Factor H does not bind to the C-reactive protein as well as the conventional one which suggests that those individuals carrying this different type are more susceptible to inflammation and the build up of drusen.
In most cases Factor H acts as a braking mechanism thereby inhibiting high C-reactive protein levels, and protects the eye from damage to the retina. C-reactive protein also prevents Factor H from banding together in clumps and hastening the formation of drusen.
In the typical group of individuals suffering from AMD, those without the genetically modified blood protein, Factor H presents as being helpful in restraining C-reactive protein from getting out of control, and being responsive to C-reactive protein as an inhibitor of drusen build up.
While there is no cure for AMD, this new insight into the natural defence mechanisms of the eye will help to design therapies that are aimed at more effective treatment of symptoms, and delay the progression of disease.