Age-Related Macular Degeneration
What Is Age-Related Macular Degeneration?
As we get older, our vision naturally begins to change. Some of these changes are easily corrected with the help of glasses, contact lenses, and other vision aids. However, age also brings an increased risk for serious vision conditions. One of the most common causes of vision loss in adults over the age of 50 is a condition known as age-related macular degeneration (AMD). It affects an estimated 11 million individuals in the US.
AMD affects a part of the eye known as the retina. Lining the back of the eye, the retina is a small but complex multi-layered tissue that serves as one of the primary mechanisms behind our ability to see. The retina contains photoreceptive neurosensory cells known as rods and cones. When light enters the eye, it refracts through the lens until it hits the retina. The retina’s rod and cone cells convert the light into neural signals that are sent directly to the visual cortex of the brain through the optic nerve, which is connected to the retina. The visual cortex then processes, organizes, and integrates the visual information into a cohesive image.
Rods and cones process light in different ways; rods are responsible for our peripheral vision and the ability to see in low-light situations, whereas cones are responsible for color perception and visual acuity. Rods are primarily concentrated along the outer edges of the retina (also known as the peripheral retina), while cones are more centrally located. The central area of the retina with the highest concentration of cones is the macula. Measuring less than a quarter of an inch in diameter, the macula is the part of the eye that’s activated whenever we do everyday activities like reading, driving, or focusing on fine details (e.g. threading a needle).
As a person gets older, the macula can begin to atrophy and degrade, making it increasingly difficult to perform these tasks. As time goes on, a patient with AMD may lose the ability to see things within their central visual field, with their peripheral vision remaining normal. To illustrate what this might look like, imagine looking at a round picture on a wall but only being able to see the picture frame.
Types of Age-Related Macular Degeneration
AMD is classified into two distinct subtypes. The more common one is known as dry AMD, also sometimes referred to as atrophic AMD. Approximately 90% of patients with AMD have this form. Dry AMD occurs as the macular tissue wears thin with age and typically causes a gradual loss of vision.
About 10% of patients with AMD will eventually develop wet AMD. Also referred to as exudative or neovascular AMD, this version of the disease is far more serious. Wet AMD is characterized by abnormal changes in the retinal vascular system, specifically the growth of fragile, unhealthy blood vessels under the retina. These blood vessels do not function normally and tend to break easily, leaking fluid and blood and scarring the macular tissue. Vision loss with wet AMD can be significant, permanent, quick, and severe.
How Is Age-Related Macular Degeneration Treated?
Currently, there are no treatments available for dry AMD. The primary treatment protocol for this version of the disease is to have your eyes regularly examined by a retina specialist so that they can monitor the disease’s progression. Although there are no medications or procedures available for dry AMD, there are some preventative measures that may be recommended, such as taking specific vitamins.
Wet AMD, on the other hand, is often treated using a class of medications that hinder the growth of abnormal blood vessels. This medication works by inhibiting signal chemicals known as vascular endothelial growth factors (VEGFs), which trigger the growth of new blood vessels. Although VEGFs play an important role in fetal development and recovery after an injury, they can also contribute to disease when overexpressed. The anti-VEGF medications help to diminish this overexpression in the retina, which helps to slow vision loss.
The most common anti-VEGF medications used to treat neovascular retinal diseases are aflibercept (Eylea), brolucizumab (Beovu), and ranibizumab (Lucentis). Bevacizumab (Avastin) is also sometimes used, but is considered off-label for the treatment of wet AMD. These medications are administered directly into the eye via injection using a very small, fine needle. Most patients need to receive injections regularly every few weeks or months.
The idea of getting eye injections is understandably scary for many patients. However, the actual process is much more comfortable than patients initially imagine. Retina specialists take great care to make sure the patient’s eyes are sterilized and numbed before beginning the procedure. This helps prevent infection and minimize discomfort. The injection takes only a few seconds to complete and most patients feel only a little bit of pressure at the injection site. Furthermore, the risk of experiencing complications, such as injuries or infections, from anti-VEGF injections is very low.
Schedule a Consultation for Age-Related Macular Degeneration
To learn more about age-related macular degeneration or schedule a visit with one of our retina specialists, call Pacific Northwest Retina toll-free at (800) 331-3719 or (206) 215-3850. We have locations in Seattle, Bellevue, Bellingham, Burlington, Mountlake Terrace, Kent, and Ellensburg.