Age-related macular degeneration (AMD) is a common eye condition that primarily impacts central vision, making tasks like reading or recognizing faces challenging. This condition affects the macula, a crucial part of the retina responsible for sharp, detailed sight. Understanding the specific characteristics of its two main forms, dry and wet, can help clarify their distinct impacts on vision.
Understanding Dry Macular Degeneration
Dry macular degeneration is the more prevalent form of AMD, accounting for approximately 85% to 90% of all cases. This condition progresses at a slower rate, developing over several years. Its mechanism involves the gradual thinning of the macula and the accumulation of tiny yellow deposits known as drusen, which are waste products from retinal cells.
As drusen increase in size and number, they can interfere with the macula’s function, leading to a slow decline in central vision. Symptoms include blurred central vision, making fine details difficult to discern. Individuals may also experience difficulty recognizing faces or require more light for reading and close-up tasks.
Understanding Wet Macular Degeneration
Wet macular degeneration is less common but more severe than its dry counterpart. This form is characterized by the growth of abnormal and fragile blood vessels beneath the retina, a process known as choroidal neovascularization. These new vessels are prone to leaking blood or fluid into the macula, which can rapidly damage the light-sensitive cells.
The leakage and subsequent scarring lead to a sudden onset of symptoms and a quicker loss of central vision. Individuals with wet AMD report distorted vision, such as straight lines appearing wavy or bent. They may also notice blind spots in their central field of vision or experience a rapid decline in overall central visual acuity.
Distinguishing Features
The primary distinction between dry and wet macular degeneration lies in their underlying mechanisms. Dry AMD involves the gradual thinning of macular tissue and the formation of drusen deposits. In contrast, wet AMD is defined by the abnormal growth of fragile blood vessels that leak fluid or blood beneath the retina.
Their progression rates also differ significantly; dry AMD advances slowly over years, whereas wet AMD can lead to sudden vision loss within weeks or months. Dry AMD is more prevalent, but wet AMD is responsible for a majority of severe vision loss. Visually, dry AMD presents with gradual blurriness and difficulty in low light. Wet AMD is marked by acute symptoms like distorted or wavy lines, blind spots, and a sudden reduction in central vision.
Management and Treatment
Management strategies for dry and wet macular degeneration vary considerably due to their distinct biological processes. For dry AMD, there is currently no treatment to reverse the damage, but interventions can help slow its progression. The Age-Related Eye Disease Studies (AREDS and AREDS2) have shown that a specific formulation of high-dose antioxidant vitamins and minerals can reduce the risk of progression to advanced stages. Lifestyle adjustments, such as a healthy diet, regular exercise, and smoking cessation, are also recommended to support eye health and slow disease advancement.
For wet AMD, active treatments target abnormal blood vessel growth and leakage. The primary treatment involves anti-vascular endothelial growth factor (anti-VEGF) injections directly into the eye. These medications, such as ranibizumab, aflibercept, and bevacizumab, block a protein that stimulates blood vessel growth and leakage, helping to stabilize or improve vision. These injections are typically administered regularly, often every four to twelve weeks, with the frequency determined by individual response. Regular monitoring using imaging techniques like optical coherence tomography (OCT) assesses treatment effectiveness and guides ongoing care.