Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is the most common cause of vision loss in individuals over the age of 50. The name of the condition derives from its cause: damage to the macula, the most sensitive spot on the retina, required for clarity in the center of the vision.
Damage to the macula results in retinal tissue degeneration that gradually worsens, diminishing or destroying central vision.
The speed at which AMD advances is variable. In some patients, the condition progresses slowly and the changes in vision are imperceptible for some time. In others, the disease moves at an accelerated pace, leading relatively quickly to loss of central vision in one or both eyes. While AMD does not result in complete blindness because some peripheral vision always remains, it does make ordinary activities, particularly those that require close visual acuity, increasingly difficult.
Types of Macular Degeneration
Macular degeneration can be classified as either dry (non-neovascular) or wet (neovascular). Dry macular degeneration is the more common diagnosis and is considered to be an early stage of the disease. This form of the disorder usually develops as the macular tissues thin during aging. Deposits of pigment within the macula may also occur.
In only a small percent of patients does the condition progress to the more advanced form of the disease. If this occurs and the patient develops wet macular degeneration, new abnormal blood vessels develop beneath the macula, causing a leakage of blood and fluid. This leakage can lead to the creation of blind spots and permanent damage to central vision.
The exact cause of macular degeneration is not exactly known.
Early detection is key in preserving vision and preventing vision loss for a longer period.
Risk Factors for Macular Degeneration
As people age, everyone is at risk for macular degeneration, but some people are at elevated risk due to genetic and/or environmental factors.
Macular degeneration is most common in females and people with light eye color, and the risk for all patients increases as they age.
Individuals over the age of 50 with a family history of the disease are at increased risk of developing AMD. Environmental factors may also increase risk.
Other factors that may increase the risk of developing macular degeneration include:
- Blue Eye color
- High fat diet
- Elevated cholesterol levels
- Prolonged sun exposure
- High blood pressure
- Certain medications
Patients can minimize their risk of macular degeneration by exercising, eating a diet rich in Omega-3 fatty acids, and getting regular eye examinations.
Symptoms of Macular Degeneration
Just as there are a number of signs that indicate the presence of AMD to the Ophthalmologist, there are a number of symptoms experienced by the patient. Visual symptoms of macular degeneration may include:
- Shadowy areas in the central vision
- Fuzzy and distorted vision
- Difficulty perceiving color
- Difficulty seeing fine details
- Blind spots in central vision
- Wavy lines
- Gradual lessening of color perception
- Distorted or blurry vision
- Dimmed vision, especially when reading
- Dark spots in the center of the visual field
If the disease progresses to the wet form, patients may also perceive straight lines as wavy or crooked, and have larger and larger blind spots, increasingly losing central vision. With wet macular degeneration, central vision loss can occur rapidly, sometimes in as little as a few days or weeks.
Macular degeneration may necessitate many lifestyle changes as it progresses. Patients may lose the ability to drive, have difficulty reading, and have difficulty recognizing faces. Because they retain peripheral vision, however, they usually remain capable of managing independently.
Diagnosis of Macular Degeneration
The Ophthalmologist may be able to detect early signs of macular degeneration through a regular eye examination while the patient is still asymptomatic. Any signs of this condition can be further confirmed by testing a patient's central vision with an Amsler grid test.
Treatment of AMD
While there is not yet a cure for macular degeneration, many patients have been helped greatly by recent innovations in treatment. Regular eye exams to facilitate early detection of AMD are essential since most therapies work best when started at an early stage of either type of the disorder.
It is essential for patients with macular degeneration, wet or dry, to seek continuous medical treatment to manage the condition and prevent permanent vision loss.
Even though treatments cannot reverse the disease process, they are often able to stop the progression of symptoms so the patient can maintain as much vision as possible.
Intraocular injections of vascular endothelial growth factor are often successful in stopping abnormal blood vessel growth in wet macular degeneration. The medications are injected into the vitreous of the eye on a monthly basis to control the damaging effects of wet macular degeneration.
Recommended treatments for AMD may include one or more of the following, each of which approaches controlling AMD in a somewhat different way:
- Vitamin supplementation known as AREDS2
- Injections of anti-VEGF (vascular endothelial growth factor)
- Laser therapy
- Laser submacular surgery
- Use of low vision aids
An innovative device, known as an implantable miniature telescope (IMT) has been designed to be implanted in place of the patient's natural lens. While not a cure for AMD, it offers hope for much-improved vision for those with the disorder.