Age-related Macular Degeneration (AMD) Quiz

Study Notes

Definition and Epidemiology

Age-related macular degeneration (AMD) is a chronic degenerative disorder that affects older individuals, characterized by central visual loss.
AMD is the leading cause of irreversible blindness in people over 50 years in developed countries.
It affects 1 in 7 people over 50 years.
AMD is the leading cause of legal blindness and severe vision loss in Australia.

Risk Factors

Advanced age: risk increases from ~2% in people aged 50 years to >30% in people aged >75 years.
Smoking: increases oxidative damage, and incidence increases with more smoking.
Hypertension
Obesity
Cardiovascular disease
Female gender
White ethnicity
Certain ocular conditions: blue iris color, hyperopia, and cataract
Family history: a significant risk factor for AMD
Genes implicated as risk factors: Complement factor H (CFH), Apolipoprotein E2 (APOE), Fibulin 5, and ABCA4

Role of RPE

Melanin absorbs excess light to prevent UV damage
Regenerates visual pigments
Forms the outer blood ocular barrier
Balances fluid and electrolytes
Phagocytoses spent outer disc segments
Maintains chorio-capillaries

Pathogenesis of AMD

RPE dysfunction
Alteration in Bruch's membrane and the extracellular matrix
Oxidative damage
Inflammatory processes
Ischemia
Drusen: a metabolic waste product between RPE and Bruch's membrane
Sub-retinal inflammation elicited by drusen leads to further damage and ischemia

Types of AMD

Dry (non-exudative): 90%, characterized by drusen and RPE dysfunction leading to geographic atrophy
Wet (exudative): 10%, characterized by the formation of choroidal neovascularization (CNV) leading to retinal fibrosis and disciform scarring

Drusen

Early signs of AMD
Round yellow deposits located between Bruch's membrane and RPE
Can be seen in healthy eyes due to aging (small and hard drusen)
Classified by size: small (< 63 µm), intermediate (63 – 124 µm), and large (> 125 µm)
Hard drusen: small, bright yellow, solid appearing drusen with well-defined margins
Soft drusen: large, pale yellow, ill-defined, fluffy margins; high risk for neovascular AMD

Description

Test your knowledge of age-related macular degeneration, a chronic degenerative disorder that affects older individuals and causes central visual loss. Learn about its epidemiology, symptoms, and types.