Macular Degeneration (AMD) is age related and common eye disease (ARMD, which causes deterioration of the macula (approximately 3 – 5 millimeters), which is the central area of the retina. This area is a paper-thin tissue at the back of the eye, where millions of light sensitive cells send visual signals to the brain. The macula processes sharp or clear straight ahead vision. When the macular becomes damaged, causes the development of blind spots, blurry or distorted vision. This can impede daily activities or simple tasks, which requires good eyesight, such as driving or reading, increasingly becomes difficult. There are two types of AMD: Milder “dry” (non-neovascular) form and more sever “wet” (neovascular) form. The dry AMD cause degeneration of the macula slowly, and becomes progressively worse over months or years. Most of the time, this disease starts in one eye, and then occurs in the other eye. Studies have shown, taking certain vitamins can slow down the degeneration of the disease, but unfortunately no cure. The “wet” form of AMD is caused, when new blood vessels grow from the choroid underneath the macular portion of the retina. These new vessels are called choroidal neovascularization (CNVs). These vessels will leak fluid or blood, which is refereed to as “wet” macular degeneration, thus causing vision loss or damage. Researchers are evaluating various reasons for this disease. Ten to eleven percent of those having “dry” AMD, will develop ‘”wet” macular degeneration. In selected cases wet macular degeneration can be treated effectually, by laser photocoagulation, which seals leaking or bleeding vessels. However, this treatment does not restore vision, but may prevent further loss. In the United States, macular degeneration is a major cause of visual impairment, and leading cause of blindness, in people over age 55. Middle aged adults have a two percent chance of getting AMD, while the risk increases to more than thirty percent in people in their seventy’s. The ‘Archives of Ophthalmology’ in 2004 estimated that 1.75 million U.S. residents had significant symptoms associated with age – related macular degeneration, and expects the number to grow to three million by 2020.
Those developing the beginning stage of macular degeneration, require more light when close-work is necessary, newspapers will be harder to read, straight signs or street signs will be harder to recognize, grid on a map will look distorted or crooked, and upon visually looking at object or item, gray or blank spots will obstruct the center of vision. Also, colors will appear less bright, and difficulty recognizing faces. The condition will gradually or rapidly lead to severe vision loss in one or both eyes and develop, as you get older.
Recent studies have shown causes of macular degeneration. According to published edition of the ‘American Journal of Human Genetics’ – published March 6, 2006. Researchers at Duke University Medical Center and Vanderbilt University Medical Center, discovered a gene called ‘LOC387715,’ which is found in cigarette smoking. Cigarette smokers are susceptible to acquire this gene, which can lead to the onset of macular degeneration. Also, if someone in your family had macular degeneration, than family members have a higher risk of acquiring this type of gene. Researchers concluded that sixty-one percent of macular degeneration is related to the gene ‘LOC387715.’ In 2006, researchers at Columbia Medical Center, pinpointed the role of two genes – Factor ‘H’ and Factor ‘B’, which form the development of nearly three out of four cases of age – related macular degeneration. There findings, indicated that seventy-four percent of AMD patients carry certain variants in one or both of these genes, which significantly increases the risk getting this disease.
According to published research study in the January 2006 issue of ‘American Journal of Ophthalmology,’ discovered that patients with elevated homocysteine in their blood, which is an amino acid, known as a biomarker for cardiovascular disease, increases the risk of developing macular degeneration. The amount of homocysteine can be reduced by taking vitamin ‘B6,’ ‘B12,’ and folate (A water-soluble ‘B’ vitamin that occurs naturally in foods such as: Leafy green vegetables, fruits, dried beans or peas.) Another study has linked AMD, when being exposed to heavy secondhand smoke. Also, nicotine makes wet macular degeneration worse. Additionally, being severely overweight increases the chance of getting either stage of AMD disease, and exposure to ultraviolet light, increasing the risk for developing macular degeneration.
Clinical studies have shown, during macular degeneration the presence of drusen or extra cellular deposits, which accumulate beneath the retinal pigment epithelium. The epithelium is a layer of cells that perform various functions: Protection and nourishment of the retina and removal of waste products. The presents of drusen increases the risk factor for developing wet AMD, and small yellowish deposits form, within layers of the retina (part of the eye which converts light into nervous signals). According to research published in February 2006, issue of the “Proceedings of the National Academy of Sciences, Dr. Jayakrishan Ambati, University of Kentucky Healthcare physician and Associate Professor and Vice Chairman of the Department of Ophthalmology and Visual Sciences, discovered that bioactive fragments found in drusen, stimulates the progression of AMD to the worst advance or wet stage. Further studies are underway, leading to blocking those components, preventing the occurrence of AMD from dry to wet stage.
Diagnosis for macular degeneration performed by: Ophthalmologist or optometrist. The doctor will dilate the pupil with eye drops, and examine the interior of each eye, looking at the retina for the presence of yellow bumps, called drusen, and observing for any changes in the macula, such as thinning. Patients may undergo Amsler Grid Test, which will check for spots of sight loss. Evaluating the extent of damage from AMD, the doctor may use a pluorescein angiography. During the procedure a fluorescein dye is injected into a vein in the arm, and photographs are taken of the back of each eye, as the dye passes through blood vessels in the retina and choroid. Examining photographs will show changes in macular pigmentation or the extent of abnormal blood vessels in the macula.
Eating fish more than four times a week reduces the risk of macular degeneration by forty percent, especially eating canned tuna. Fish is a major source of DHA (an omeg-3 fatty acid), which reduces the risk of AMD, and eating any type of nuts. Also, a diet that derives 20 -25 percent total calories from fat is healthier and helps treat AMD patients.
Certain drugs approved by Food and Drug Administration (FDA) for treating AMD. In December 2004, the FDA approved pegaptanib (Macugen) treating wet AMD. The medication is injected into the vitreous fluid in the eye, and targets the proten, causing the growth of abnormal blood vessels, and decreases the leakage from existing blood vessels. Similar to this drug is ranibizumab (Lucentis) for treating wet macular degeneration, and being tested in clinical trials. Lucentis has the promise to reverse the effects of AMD and preventing further vision loss. Hopefully, in 2006 the FDA will approve Lucentis after final phase of clinical trials. The drug bevacizumab (Avastin) is related to Lucentis, has similar effects, for treating wet AMD, and injected directly into the eye. Also under review is Evizon (squalamine lactate), which is given intravenous infusion, for treating several types of cancer and wet macular degeneration.
According to research conducted by Lucian V. Del Priore, MD and PHD, a procedure surgically removes the new blood vessels, growth found in wet macular degeneration. Then replacing them with healthy donated cells, which should migrate, and populate the damaged retinal pigment layer without rejection. This transplant technique should improve vision.