Age-related macular degeneration (AMD) is a progressive eye condition that primarily affects the macula, the small central part of the retina responsible for sharp, straight-ahead vision. Damage to this area can lead to a loss of central vision, which is necessary for tasks like reading and recognizing faces. AMD occurs in two distinct forms, known as dry and wet, which differ significantly in their underlying causes, rate of progression, and overall threat to eyesight.
Understanding Dry Macular Degeneration
Dry AMD is the most frequently diagnosed form, accounting for approximately 85% to 90% of all cases. It develops when small, yellowish deposits called drusen accumulate underneath the macula, causing the macula to gradually thin and deteriorate.
Vision loss is typically slow and gradual, often developing over many years. Early symptoms may include a need for brighter light when reading or difficulty adapting to low-light environments. As the condition advances, a blurred spot can appear in the center of the vision.
Understanding Wet Macular Degeneration
Wet AMD is the less common form, but it is substantially more aggressive and poses a much greater risk to vision. This form is characterized by a process called neovascularization, which involves the growth of fragile, abnormal new blood vessels beneath the macula.
These newly formed vessels are weak and prone to leakage, seeping blood and fluid into the retina. This fluid leakage quickly damages the light-sensitive cells in the macula, often causing the formation of scar tissue. Vision impairment can be rapid and dramatic, sometimes occurring within days or weeks.
Comparing Vision Loss and Treatment Urgency
Wet AMD is definitively the more serious form because it causes a rapid and severe loss of central vision. The sudden fluid accumulation and damage from leaky blood vessels can quickly distort vision, making straight lines appear wavy or bent. This rapid deterioration contrasts sharply with the slow, gradual progression seen in the dry form.
For dry AMD, the primary approach focuses on monitoring and utilizing preventative measures. Nutritional supplements, such as the Age-Related Eye Disease Study 2 (AREDS2) formula, are often recommended to slow progression in intermediate and advanced dry AMD.
Wet AMD, however, is considered a medical emergency that demands immediate action. The gold standard treatment involves anti-vascular endothelial growth factor (anti-VEGF) medications, which are injected directly into the eye. These injections block the growth of abnormal, leaking blood vessels, which can stop the leakage and often stabilize or even improve vision.
While dry AMD can remain stable for years, it can unexpectedly progress to the more severe wet form at any time, underscoring the need for consistent monitoring. Once vision is lost due to scar tissue, it is often permanent.