Age-related macular degeneration (AMD) is a progressive eye condition and a leading cause of severe, irreversible vision loss in older adults. It affects the macula, the small central part of the retina, impairing the detailed, straight-ahead vision necessary for tasks like reading and recognizing faces. Concerns about total vision loss, or blindness, are common, but the risk depends heavily on the disease stage and type.
Defining the Risk of Severe Vision Loss
The concern about “going blind” from AMD generally refers to legal blindness—a severe reduction in central vision—not a complete loss of all light perception. Legal blindness is defined as a corrected visual acuity of 20/200 or worse in the better-seeing eye. Total blindness, meaning the complete absence of light perception, is extremely rare because AMD typically spares the peripheral, or side, vision.
The risk of severe vision impairment varies significantly across the entire population of AMD patients. Approximately 10% to 15% of all Age-related Macular Degeneration cases progress to the late, advanced stages that cause the most significant vision loss. The less common Wet form is responsible for about 90% of legal blindness cases attributed to AMD. For the overall population of individuals diagnosed with late-stage AMD, the prevalence of legal blindness is estimated to be around 5.4%.
Understanding Dry and Wet Macular Degeneration
The likelihood of severe vision loss is primarily dictated by which of the two main types of AMD is present. The vast majority of diagnoses, about 90%, are the Dry (atrophic) form, which typically advances slowly over many years. Dry AMD is characterized by the accumulation of small yellow deposits called drusen beneath the retina and the gradual breakdown of light-sensitive cells in the macula.
Although Dry AMD is less aggressive, it can still lead to severe vision impairment if it progresses to Geographic Atrophy (GA), an advanced stage where macula tissue death occurs. The Wet (neovascular or exudative) form is far less common, accounting for about 10% of cases, but it is responsible for the majority of rapid and severe vision loss. Wet AMD is always preceded by the dry form and involves the uncontrolled growth of new, fragile blood vessels under the macula.
These abnormal vessels leak fluid and blood, causing scar tissue and rapid damage to the macula, which can lead to profound vision loss within weeks or months without intervention. About 10% to 15% of people with Dry AMD will eventually progress to the more damaging Wet form. This transition dramatically increases the risk of severe vision impairment for a patient.
Key Factors That Influence Disease Progression
Several factors influence how quickly AMD progresses to advanced stages. Smoking is the single most significant controllable risk factor, accelerating the disease and considerably increasing the risk of developing advanced AMD. The risk of progression also increases prominently with age, rising from about 2% for those in their 50s to nearly 30% for individuals over 75.
Genetic predisposition plays a substantial role, as certain genetic variations, such as those in the Complement Factor H (CFH) gene, influence the rate at which intermediate AMD advances to the late stage. Nutritional factors are also relevant, particularly a diet lacking in specific antioxidants and minerals. A poor diet contributes to the oxidative stress and inflammation that drives the deterioration of the macula.
How Treatment Affects the Percentage of Vision Loss
Modern medical interventions have dramatically improved the prognosis for patients and significantly reduced the percentage of those who experience severe vision loss. This improvement is most notable in the treatment of Wet AMD, the form that causes most legal blindness. The introduction of anti-vascular endothelial growth factor (anti-VEGF) injections has revolutionized care.
These treatments work by blocking the protein that signals the abnormal blood vessels to grow and leak, effectively stabilizing vision for many patients. Anti-VEGF therapy has been shown to maintain visual acuity in over 90% of treated eyes. The success of this treatment has been so substantial that the rate of blindness attributed to AMD has dropped by an estimated 50% to 70% since these medications became widely available.
For the more common Dry AMD, treatment involves specific high-dose vitamin and mineral supplements, such as the AREDS formulation. These supplements can slow the progression from the intermediate stage to the advanced stages that cause vision loss.