Age related macular degeneration(ARMD)
AMD is deterioration of the macula, which is the small central area of the retina of the eye that controls visual acuity.
Types Of Macular Degeneration
Macular degeneration is diagnosed as either dry (non-neovascular) or wet (neovascular). Neovascular refers to growth of new blood vessels in an area, such as the macula, where they are not supposed to be.
The dry form is more common than the wet form, with about 85 to 90 percent of AMD patients diagnosed with dry AMD. The wet form of the disease usually leads to more serious vision loss.
Dry macular degeneration (non-neovascular). Dry AMD is an early stage of the disease and may result from the aging and thinning of macular tissues, depositing of pigment in the macula or a combination of the two processes. Dry macular degeneration is diagnosed when yellowish spots known as drusen begin to accumulate in and around the macula. It is believed these spots are deposits or debris from deteriorating tissue.
Gradual central vision loss may occur with dry macular degeneration but usually is not nearly as severe as wet AMD symptoms. However, dry AMD through a period of years slowly can progress to late-stage geographic atrophy (GA) — gradual degradation of retinal cells that also can cause severe vision loss.
Two large, five-year clinical trials — the Age-Related Eye Disease Study (AREDS; 2001) and a follow-up study called AREDS2 (2013) — have shown nutritional supplements containing antioxidant vitamins and multivitamins that also contain lutein and zeaxanthin can reduce the risk of dry AMD progressing to sight-threatening wet AMD.
Wet macular degeneration (neovascular). In about 10 percent of cases, dry AMD progresses to the more advanced and damaging form of the eye disease. With wet macular degeneration, new blood vessels grow beneath the retina and leak blood and fluid. This leakage causes permanent damage to light-sensitive retinal cells, which die off and create blind spots in central vision.
Choroidal neovascularization (CNVM), the underlying process causing wet AMD and abnormal blood vessel growth, is the body’s misguided way of attempting to create a new network of blood vessels to supply more nutrients and oxygen to the eye’s retina. Instead, the process creates scarring, leading to sometimes severe central vision loss due to fluid or even haemorrhage.
Wet macular degeneration falls into two categories:
Occult. New blood vessel growth beneath the retina is not as pronounced, and leakage is less evident in the occult CNV form of wet macular degeneration, which typically produces less severe vision loss.
Classic. When blood vessel growth and scarring have very clear, delineated outlines observed beneath the retina, this type of wet AMD is known as classic CNV, usually producing more severe vision loss.
Symptoms
- Central blurry vision
- Unusually fuzzy or distorted vision
Ophthalmologist often detect early signs of macular degeneration before symptoms occur. Usually this is accomplished through a retinal exam. When macular degeneration is suspected, An Amsler grid test that measures your central vision may be performed.
If your eye doctor detects some defect in your central vision, such as distortion or blurriness, he or she may order a fluorescein angiography to examine the retinal blood vessels surrounding the macula
Risk factors
- Ageing-For those over 60 years of age, the rate is one in eight (12.5 percent); and for seniors over 80, one in three (33 percent) has AMD
- Obesity and inactivity
- Smoking
- High blood pressure (hypertension)
Treatment for Early Dry AMD
The treatment for early dry AMD is generally nutritional therapy, with a healthy diet high in antioxidants to support the cells of the macula.
Treatments for Wet AMD:Anti-VEGF Therapy
Anti-VEGF Therapy VEGF is an acronym for vascular endothelial growth factor. Currently, the most common and effective clinical treatment for wet Age-related Macular Degeneration is anti-VEGF therapy – which is periodic intravitreal (into the eye) injection of a chemical called an “anti-VEGF.” In the normal life of the human body, VEGF is a healthy molecule which supports the growth of new blood vessels. In the case of macular health, though, VEGF is unhealthy.
An intraocular injection of an anti-VEGF drug inhibits the formation of new blood vessels behind the retina and may keep the retina free of leakage. The procedure is usually not painful because the eye has been anesthetized. It takes about fifteen minutes. Usually the appointment requires an hour. The effect lasts for a month or maybe more.
Researchers report high rates of success with anti-VEGF injections, including receding blood vessels behind the retina, a far slower progression of the disease, and, in some cases, moderate gains made in vision. In some parts of the world, anti-VEGF treatments have reduced the incidence of legal blindness by 50 percent. However, they have noted that injections of even small amounts of anti-VEGF drugs could — though research is inconclusive — have an effect on vascular function in the rest of the body.
Types of Anti-VEGF Drugs
Several anti-VEGF drugs are being developed to inhibit VEGF by trapping it or preventing it from binding with elements which will stimulate growth.
Chemically synthesized short strands of RNA (nucleic acid) called “aptamers” prevent the binding of VEGF to its receptor. The various forms of anti-VEGF injections include ranibizumab (Accentrix, made by Novartis), bevacizumab (off label Avastin from Genentech), and the recently Food and Drug Administration-approved aflibercept (Eylea/VEGF Trap-Eye from Regeneron/Bayer). Each of these chemicals works in a different way to inhibit blood vessel growth.
Stroke or recent Heart disease is a contraindication for usage of Anti-VEGF. In few cases, clearance from a treating vascular surgeon or a cardiologist is required.