The journal “Nature” has reported that an international group of research scientists believes they have found a link between one of the leading causes of blindness and an enzyme. This raises hopes that this might lead to a cure, although no human studies have yet been carried out to verify that the link exists in humans.
Age-related macular degeneration is the commonest cause of irreversible blindness in developed countries. Over 8 million people in the US alone have some form of this disease, and more Americans are affected by AMD than are affected by cataracts and glaucoma combined.
The journal reported that the excitement is all about an enzyme known as DICER1. It seems that DICER1, stops functioning in suffers. Such links in the past have lead to cures when synthetic alternatives have been found.
The macula is the part of the eye which sits in the centre of the retina. Its function is to create for us the fine detail right we see at the centre of our field of vision.
The researchers homed in on the enzyme DICER1 when they found that it was less active in the retina of people with the most common so called, “dry degeneration form” of the affliction. They investigated further by turning-off the gene which is known to produce this enzyme in mice, and according to the journal “Nature” the test results showed that the retina cells were damaged only in those animals suffering a deficit in their DICER1.
Further investigation revealed that DICER1 carries out an essential function by destroying small particles of genetic material called Alu RNA.
If no DICER1 is present, the Alu RNA builds up causing a poisoning effect eventually leading to the decay of the retina cells which provide our central eyesight.
This closely follows what sufferers experience, as macula cells begin to deteriorate, a person loses sight in the central field of vision but peripheral vision remains intact. Macular degeneration has two forms which are commonly classified as either “dry” or “wet”. The dry form is more common than the wet (about 90 percent of patients).
Many people do not realize that this eye disease is not permanently curable.
Age-related macular degeneration is the most common cause of vision loss in individuals over the age of fifty. Thankfully, it is usually mild, but can in some circumstances have severe consequences in which the center vision is completely lost. The difficulty with macular degeneration is that although it does not cause complete blindness, it can result in the inability to read words and in time also recognize faces.
Age-related macular degeneration (AMD) is not hereditary, but may sometimes be a consequence of aging. Macular deterioration can also cause images to appear distorted , or may cause an area of cloudiness or darkness to form at the center of the persons visual field. Diseases such as diabetes and atherosclerosis may accelerate the process.
Vision rehabilitation can help patients maximize remaining vision and adapt activities of daily living. Families need encouragement in providing support and assistance as patients adjust to being partially sighted. The process is usually quite slow, and often takes years to develop.
Drugs are often prescribed to alleviate age-related macular degeneration. Prior to the discovery, company Genentech, the originator of the successful blockbuster drug Lucentis, has become the market leader and has a share of more than 90%, followed by Visudyne with their drug Verteporfin.
Vitamins C and E have not been shown to reduce risk, nor did selenium in one large study. The use of zinc has been suggested, but results have been inconclusive, with some studies showed a benefit, while others showed no benefit, and surprisingly one actually showed an increased risk of ARMD with increased levels of zinc in the blood.
Further reading on Age-Related Macular Degeneration: