Macular degeneration, also known as age-related macular degeneration (AMD), is a common condition in older adults, and the leading cause of vision loss in people aged 50 and older. Macular degeneration affects the macula, the part of the retina responsible for the crisp, detailed central vision needed for reading or driving.
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 about 10 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.
With either type of macular degeneration, peripheral vision is maintained.
Risk Factors for Macular Degeneration
As people age, they are at risk for macular degeneration, but some are at elevated risk due to genetic and/or environmental factors. Some individuals have a genetic variant known as complement factor H that makes them more likely to develop this condition. Nearly half of the cases of blindness associated with macular degeneration are linked to this genetic deficiency.
Macular degeneration is most common in females and people with light skin or eye color, and the risk for all patients increases as they age. More than 30 percent of adults age 75 and older have been diagnosed with advanced or intermediate age-related macular degeneration.
Other factors that may increase the risk of developing macular degeneration include:
- Diet high in fat
- 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
Patients with dry macular degeneration may notice gradual changes, including the following, to their vision:
- Shadowy areas in the central vision
- Fuzzy and distorted vision
- Difficulty perceiving color
- Difficulty seeing fine details
- Blind spots in central vision
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. Detecting macular degeneration and other serious eye conditions as early as possible can help to prevent permanent loss of vision.
Treatment of Macular Degeneration
While there is no cure for macular degeneration, there are several treatment options available to help patients manage this condition and preserve their vision. The best treatment option for each patient depends on the severity and type of the condition, as well as how much, if any, permanent vision loss has occurred.
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. Photodynamic therapy is also effective in removing the newly developing abnormal blood vessels characteristic of wet macular degeneration. Many patients also benefit from vitamin and mineral supplements, which help to clear out toxic substances that may build up.
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.