Macular Degeneration also known as Age-Related Macular Degeneration (AMD) is a major cause of visual impairment in the United States. Approximately 1.8 million Americans age 40 and older have advanced AMD, and another 7.3 million people with intermediate AMD are at substantial risk for vision loss. The government estimates that by 2020 there will be 2.9 million people with advanced AMD. AMD is a common eye disease that causes deterioration of the macula, the central area of the retina, the paper-thin tissue at the back of the eye where light-sensitive cells send visual signals to the brain. Sharp, clear, “straight ahead” vision is processed by the macula. Damage to the macula results in the development of blind spots and blurred or distorted vision. When the macula becomes damaged, many daily activities such as driving and reading become increasingly difficult. AMD usually affects individuals older than 50 years of age, and scientific evidence shows that genes may play a role in the development of nearly three out of four cases of this devastating eye disease.
Macular degeneration usually develops gradually and painlessly. The signs and symptoms of the disease may vary, depending on which of the two types of macular degeneration you have.
- The need for increasingly bright illumination when reading or doing close work.
- Increasing difficulty adapting to low levels of illumination, such as when entering a dimly lit restaurant
- Printed words appear increasingly blurry
- Colors appear less bright
- Difficulty recognizing faces
- Gradual increase of haziness in your overall vision
- Blurred or blind spot in the center of your visual field combined with a profound drop in your central vision acuity
- A need to scan your eyes all around an object to provide a more complete image
- Visual distortions, such as straight lines appearing wavy or crooked, a doorway or street sign that seems out of whack, or objects appearing smaller or farther away than they should
- A decrease in or loss of central vision
- A blurry spot in the center of your vision
No one knows the etiology, or cause, of age-related macular degeneration. Causes are likely to be genetically inherited, but environmental factors may also contribute. Macular degeneration often runs in families. There may be a wide variety of different genes and proteins associated with dry and wet macular degeneration. Studies of twins showed that genetic factors play a significant role in the cause. Many of the following risk factors have been found to be associated with age-related macular degeneration.
The likelihood of developing macular degeneration increases with age.
Macular degeneration is more common in whites but occurs in all races.
Macular degeneration is more common in lightly pigmented people.
As a corollary of skin pigmentation, people with a more lightly colored iris are more likely to develop some forms of macular degeneration.
Women seem to be at greater risk.
Smoking is a well-established risk factor for both forms of macular degeneration.
Those with lifelong outdoor careers or hobbies as well as those living near the equator and at high altitudes are at greater risk.
Some medications like Fosamax for osteoporosis may predispose to macular degeneration.
Family history is perhaps the most important risk factor other than age.
There are several different tests by which a qualified eye care physician can reach a macular degeneration diagnosis, each more or less useful for detecting different stages of the disease. Pupil dilation, fluorescein angiograms, and the Amsler grid test are currently the most effective ways to diagnose the disease. It is recommended that you see a specialist for a thorough diagnostic macular degeneration test and eye exam if you are over the age of 55 or are noticing any of the symptoms.
During a standard eye exam, your eye care specialist may dilate your pupils to get a fuller view of the retina and a closer examination of any possible damage or debris. The patient’s eyes will be blurry for several hours after the test. A visual examination assisted by pupil dilation is one of the best ways to detect the early, or dry, form of macular degeneration. While detection of debris and decayed tissue in the eye does not necessarily mean that the patient will develop macular degeneration, the test is useful for determining whether preventative measures should be taken to defend against it.
If an eye care specialist suspects a patient is suffering from wet macular degeneration, he or she may order a fluorescein angiogram test. During the procedure, a special dye is injected into the bloodstream through the arm. Within seconds, the dye travels through the body to the eye. A special camera is then used to highlight the dye, allowing the eye care professional to see if there are leaks or problems in the eye — and, if so, where the problems are. While there are currently no treatments available to completely repair the eye after the onset of macular degeneration, catching it early enough may allow medications to prevent further damage or even restore some lost vision.
One of the easiest methods for detecting macular degeneration is the Amsler grid test. The Amsler test is merely a square grid with black lines running parallel to each other horizontally and vertically, and a black dot in the center for the patient to focus on. A person with normal vision will see the grid as it appears on the page; however, a person with wet macular degeneration will see distortion in the lines, as if the grid has been twisted or has a hole in the middle of it. Early macular degeneration diagnosis may facilitate prevention of further vision loss, or even restore vision that has been lost.
There is as yet no outright cure for age-related macular degeneration, but some treatments may delay its progression or even improve vision. There is a variety of advanced treatments for patients with wet and dry macular degeneration, including injectable drug therapy, Photodynamic therapy, laser treatment, surgery, and vitamin and mineral supplements.
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, although nutritional intervention may help prevent its progression to the wet form.
For wet AMD, treatments aimed at stopping abnormal blood vessel growth include FDA-approved drugs of Lucentis, Macugen and Visudyne used with Photodynamic Therapy. Lucentis has been shown to improve vision in a significant number of people with wet macular degeneration.
The goal of treatment is to preserve eyesight and prevent future vision loss. There have been many recent advances in treatment for wet macular degeneration, and research in dry and wet macular degeneration is ongoing.