It’s the central portion of the retina that provides sharp, central vision needed to read, drive or recognize faces. It allows us to see the fine details when we look directly at something and damage to it may cause loss of central vision and makes it difficult for a person to read and do fine work.
Age-related macular degeneration, often called AMD or ARMD, is the leading cause of vision loss and blindness in patients over the age of 50 years. It is a painless disorder that affects the macula of one or both eyes causing progressive loss of central and detailed vision.
Does not lead to total blindness but a patient may find it difficult to do read, drive and recognize people.
The area surrounding the macula is not affected so peripheral vision remains clear and the patient can usually still move around fairly freely.
Age-related macular degeneration usually produces a slow, painless loss of vision.
Macular degeneration can be either dry (non-neovascular) or wet (neovascular). Neovascular refers to the 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 start developing 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. Yellowish spots (drusen) that form in the back of the eye or retina are an early sign of “dry” macular degeneration.
Wet Macular Degeneration (neovascular): In few 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 (CNV), 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 retina. Instead, the process creates scarring, leading to sometimes severe central vision loss.
There is no permanent cure for age-related macular degeneration, but some treatments may delay its progression or even improve vision. Treatments for macular degeneration depend on whether the disease is in its early-stage, dry form or in the more advanced, wet form that can lead to serious vision loss. No FDA-approved treatments exist yet for dry macular degeneration.
Laser treatment may stop or lessen vision loss in the early stages of the disease. It is performed with a specific wavelength designed to cauterize abnormal blood vessels. A laser beam destroys existing blood vessels and may stop the growth of new ones. A scar forms after the laser treatment. This produces a permanent loss of vision in that area of the retina, sacrificed in order to preserve the rest of the eye layer. Vision usually does not improve after laser treatment. It works in about half the cases, and only a small number of people meet the criteria for laser treatment. Its limitations have prompted a search for other forms of therapy.
A light-activated drug called verteporfin (Visudyne) is given intravenously, and a specially designed laser is used to close the abnormal vessels while leaving the retina intact. You may need several treatments over one to two years because closed blood vessels can reopen within the treated area. Because Verteporfin is activated by light, exposure to sunlight must be avoided for five days after treatment.
Vascular Endothelial Growth Factor (VEGF) causes new blood vessels to develop and increases leakage and inflammation of blood vessels. Most of these drugs are insoluble and therefore cannot be given as eyedrops. Thus, the ideal form of administration is directly into the eye with a very fine needle. These injection procedures are a form of surgical intervention and should be performed only by an ophthalmologist familiar with the technique, indications, contraindications, possible complications, and alternative therapies. Strict sterile protocols are necessary as with any surgical procedure.
Bevacizumab (Avastin) is an anti-VEGF drug that is currently approved for cancer of the colon or rectum. There is now an NIH-sponsored trial underway to scientifically compare Avastin to Lucentis. Both drugs carry a small risk to the patients of stroke. Ranibizumab (Lucentis) is an anti-VEGF for the treatment of wet age-related macular degeneration. It is administered inside the eye via the pars plana. Preliminary studies have shown an improved vision in patients with many forms of wet age-related macular degeneration.