What is macular degeneration?
The macula is the small, middle portion of the retina, which is the light sensitive lining at the back of the eye. The macula is responsible for sharp, central (straight-ahead) vision necessary for functions such as reading, driving a car, and recognizing faces.
Macular degeneration, also known as ARMD, AMD, or Age-Related Macular Degernation, is an eye disease that occurs when there is cellular damage, thinning, or any other breakdown of the macular region. Macular degeneration makes seeing objects and details straight ahead difficult or impossible. This is a chronic, progressive, and painless condition.
Two types of macular degeneration
Ninety percent of macular degeneration is called "atrophic" or "dry" macular degeneration. It is characterized by a thinning of the macular tissue and the development of small deposits on the retina called drusen. This usually develops slowly and often only causes mild visual loss. Dry macular degernation can be categorized into early, intermediate, and advanced dry macular degernation. In certain cases, dry macular degeneration can lead to wet macular degeneration.
The second form of is called "exudative" or "wet" macular degeneration, because of the abnormal growth of new blood vessels under the macula which can leak and eventually create a large blind spot in the central vision. This form of the disease is of much greater threat to vision than the more common dry type.
What are the symptoms of macular degernation?
General symptoms of macular degeneration include blurry or fuzzy central vision, a reduction in color vision, straight lines appear distorted, wavy, or crooked, and a dark or empty area may appear in the center of vision.
The symptoms of wet macular degeneration occur at a much faster rate than dry macular degeneration, which can take up to ten years before symptoms are noted.
What causes macular degeneration?
Unfortunately, the cause is not fully understood, but the aging process does at least have a partial cause. As we age, we become more susceptible to numerous degenerative processes like arthritis, heart conditions, cancer, cataracts, and macular degeneration. These conditions may be caused by the body's overproduction of free radicals.
During the everyday metabolic processes of the body, oxygen atoms with an extra electron are released. These extra electrons are quite destructive and cause cellular damage, alter DNA, and are thought to be at least partially responsible for many of the degenerative diseases mentioned above. The production of these free radicals is normal during metabolism, but the body produces its own "anti-oxidants" to neutralize them.
Some of the vitamins in the food we eat also have anti-oxidant properties. These are vitamins A, C, E and beta-carotene. Unfortunately, smoking, poor nutrition, and other lifestyle factors result in the body producing too many free radicals. For this reason, lifestyle factors may contribute to the risk of macular degeneration.
There is some evidence to suggest that macular degeneration has a genetic basis, as the condition tends to run in families. However, the exact nature of this familial tendency has not been clarified. It has been suggested from twin studies that there is a defect in the genes responsible for the integrity and health of the retina.
Exposure to certain types of light may also play a role, mainly ultraviolet, or UV, light. Studies performed on fishermen in the Chesapeake Bay suggest that long-term exposure to ultraviolet light from the sun may increase the risk of macular degeneration and other eye conditions such as the development of cataracts
Smoking cigarettes reduces the protective antioxidants in the eye, meaning that macular degeneration is more than twice common in people who smoke more than one pack of cigarettes a day, compared to people who do not smoke. The risk also remains high, even up to 15 years after quitting.
Who develops macular degenetation?
Macular degeneration is the most common cause of irreversible vision loss for people over the age of 60. It is estimated that 2.5 million people in developed countries will suffer visual loss from this disorder, and that there are approximately 200,000 new cases diagnosed every year.
Macular degeneration is most common in people over the age of 65, but there have been some cases affecting people as young as their 40s and 50s. Caucasians are at a higher risk for develoiping macular degeneration than other races. Women also develop macular degeneration at an earlier age than men.
Other risk factors include poor diet and nutrition, overexpsore to sunlight and UV, smoking, genertic factors, high blood pressure, heart disease, and diabetes.
How is macular degeneration diagnosed?
In some patients, macular degeneration advances so slowly that it will have little effect on vision for many years. In early stages, signs and symptoms may not be noticeable, so yearly comprehensive eye examinations are important for early detection.
In our yearly comprehensive eye examinations, our optometrists perform a variety of tests to determine if you have macular degeneration or other eye health problems. We assess any risk for macular degeneration, test visual acuity (the ability to see), test central and peripheral vision, take retinal photographs, check color vision, and use special magnifying lens to look at the retina through a dilated pupil.
In certain patients, we will perform an Amsler Grid evaluation. Some patients are instructed to perform this daily at their home, usually shortly after waking up. If any changes are noticed, contact our office right away. Below is an Amsler Grid you can use and instructions for it's proper use.
Some patients with a diagnosis of macular degeneration will have other scans of the back of the eye performed, usually either an OCT and/or FANG, or fluorescein angiography.
How is macular degeneration treated?
Although researchers are spending a great deal of time investigating the cause and treatment of ARMD, there is no real cure available. The goal of current treatment efforts is to attempt to stabilize the condition. Once central vision is lost, it cannot be regained, so early diagnosis is of the utmost importance.
Lifestyle changes are heavily discussed early on. These include stop smoking, eating a healthy diet, exercising, and maintaining a normal blood presure. A low-fat diet, rich in dark green leafy vegetables, including spinach, some types of leaf lettuce and broccoli, can slow vision loss due to macular degeneration.
AREDS 2 vitamins are usually suggested by our optometrist. In the AREDS (Age-Related Eye Disease Study), it was determined that our bodies need certain supplements to slow the progression of certain age-related diseases. We cannot get these vitamins in the proper amount in our everyday diet or with a standard multivitamin. There are various types of these vitamins, so please speak with our optometrists to determine which would be best for you.
Please note that smokers should not take any supplements or vitamins that contain high levels of betea carotene (>25,000 IU) or high levels of zinc.
For the more severe wet form of the disease, patients are referred to ophthalmologists for anti-VEGF (vascular endothelial growth factor) drugs which are delivered via a shot into the eye. Usually several treatments needed, about once a month. These drugs block the trouble-causing VEGF, reducing the growth of abnormal blood vessels and slowing their leakage. This is not a permanent cure, but it can be used to slow the rate of central vision loss.
Other options include laser photocoagulation, which involves directing a beam of laser light at the abnormal blood vessels in order to destroy them and prevent their leaking. Provided that the blood vessels have not grown under the macula, this treatment can be helpful in arresting the progress of the disease. If the blood vessels are already under the macula, the laser may cause scarring and permanent vision loss.
Photodynamic therapy (PDT) is also an option. A drug, injected into the arm travels to the affected eye and is then exposed to a non-thermal red light. This light activates the drug to close and seal off the abnormal blood vessels. The entire treatment only takes about 30 minutes and requires no anesthetic.
Several new treatments are still under development as well. These procedures may preserve more sight overall, though they are not cures that restore vision to normal. Our optometrists and the ophthalmologists we work with will help you make the decision for which treatment is best for you.
Low Vision Devices
Patients can be fit with low vision devices to help perform certain activities when some vision hasbeen lost due to macular degeneration. These telescopic and microscopic lenses, magnifying glasses, illuminated magnifiers, and closed circuit television systems can be prescribed to help make the most effective use of remaining vision and restore function.
What is the prognosis for macular degeneration?
The effect of this disease can range from mild vision loss to central blindness. Since macular degeneration progression can be avoided with early intervention, it is important that you maintain your regular eye examinations, returning every 6-12 months, depending on the advice of our optometrists and you follow all instructions given to you.