Age-Related Vision Loss
Age-related macular degeneration (AMD) is a disease associated with aging that gradually destroys sharp, central vision. Central vision is needed for seeing objects clearly and for common daily tasks such as reading and driving. Though it doesn’t cause pain, AMD affects the macula, the part of the retina that allows you to see fine detail. In some cases, AMD advances so slowly that people notice little change in their vision. In others, the disease progresses faster and may lead to a loss of vision in both eyes. AMD is a leading cause of vision loss in Americans 50 years of age and older.
Wet Macular Degeneration
AMD occurs in two forms: wet and dry.
Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. These new blood vessels tend to be very fragile and often leak blood and fluid. Damage to the macula occurs rapidly.
With wet AMD, loss of central vision can occur quickly. An early symptom of wet AMD is that straight lines appear wavy, or a dark spot appears in the center of the vision. If you notice this condition or other changes to your vision, contact your eye care professional at once. You need a comprehensive dilated eye exam.
Treatment of Wet Macular Degeneration
One option to slow the progression of neovascular or wet AMD is to inject drugs into the eye.
With wet AMD, abnormally high levels of vascular endothelial growth factor (VEGF) are secreted in the eyes. VEGF is a protein that promotes the growth of new abnormal blood vessels. Anti-VEGF injection therapy blocks this growth.
If you get this treatment, you may need multiple monthly injections. Before each injection, your eye will be numbed and cleaned with antiseptics. To further reduce the risk of infection, you may be prescribed antibiotic drops.
In this treatment procedure, the doctor injects a drug called Visudyne into the arm and activates the drug as it passes through the abnormal blood vessels by shining a low-energy laser beam into the eye. Visudyne is activated by the laser light, which produces a reaction that destroys abnormal blood vessels. The procedure is virtually painless.
Photodynamic therapy slows the rate of vision loss; it does not stop vision loss or restore vision in eyes already damaged by advanced AMD. Treatment results often are temporary and you may need to be treated more than once. This treatment is less common than anti-VEGF injections and is often used in combination with them for specific types of wet AMD.
Eye care professionals treat certain cases of wet AMD with laser surgery, though this is less common than other treatments. A "hot" laser is aimed at the abnormal blood vessels in your eyes to destroy them. This laser is not the same one used in photodynamic therapy, which may be referred to as a "cold" laser.
This treatment is more likely to be used when blood vessel growth is limited to a compact area in your eye, away from the center of the macula, which can be easily targeted with the laser. Even so, laser treatment also may destroy some surrounding healthy tissue.
This often results in a small blind spot where the laser has scarred the retina. The size and location of this blind spot will vary with where the abnormal blood vessels were. If the abnormal blood vessels were small, and not too close to the macular center, there may only be a small blind spot that the patient does not even notice. However, it is much more common for the abnormal blood vessels to be large and close to the center of the macula. Laser treatment then results in a noticeable blind spot. Still, this blind spot is often not as bad as the vision damage from the untreated blood vessels.
Dry Macular Degeneration
Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye. As dry AMD gets worse, you may see a blurred or gray spot in the center of your vision. Over time, as less of the macula functions, central vision is gradually lost in the affected eye.
The most common symptom of dry AMD is blurred vision. You may have difficulty recognizing faces. You may need more light for reading and other tasks.
Dry AMD generally affects both eyes, but vision can be lost in one eye while the other eye seems unaffected. One of the most common early signs of dry AMD is drusen – yellow deposits under the retina often found in people over age 60.
Dry macular degeneration can sometimes lead to significant vision loss, but milder visual symptoms are more likely. More severe vision loss is usually due to wet macular degeneration. That’s why the wet form is considered more serious. Still, even with wet macular degeneration, complete vision loss is very unlikely.
Patients who lose central vision may be unable to drive, read and perform other tasks that require sharp vision, but they almost always maintain peripheral vision. This usually allows them to walk around without assistance and perform other activities that do not require sharp central vision
Treatment of Dry Macular Degeneration
Once dry AMD reaches the advanced stage, no form of treatment can prevent vision loss. However, treatment can delay and possibly prevent intermediate AMD from progressing to the advanced stage, in which vision loss occurs.