Macular Degeneration, Age-Related
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- Age-related macular degeneration (ARMD) is the leading cause of irreversible, severe visual loss in persons age >65 years.
- ARMD results in pigmentary changes in the macula or typical drusen associated with visual loss to the 20/30 level or worse, not caused by cataract or other eye disease, in individuals >50 years of age, although some definitions exclude age or visual acuity criteria.
- System(s) affected: nervous
- Synonym(s): senile macular degeneration; subretinal neovascularization (SRN)
- Neovascular/exudative form is rare in blacks and more common in whites.
- Predominant sex: female
- In the Framingham Eye Study (FES), drusen were noted in 25% of all participants who were ≥52 years of age. ARMD-associated visual loss was noted in 5.7%.
- Atrophic/nonexudative stage accounts for 20% of cases of severe visual loss.
- Neovascular/exudative stage accounts for 80% of cases of severe visual loss.
Per FES study:
- People 65 to 74 years old: 11%
- People ≥75 years old: 27.9%
Etiology and Pathophysiology
- Breaks in the Bruch membrane allow choroidal neovascular membranes (CNVMs) to invade the retinal pigment epithelium (RPE) and grow into the subretinal space.
- Atrophic/nonexudative: drusen and/or pigmentary changes in the macula
- Neovascular/exudative: growth of blood vessels underneath the retina
- Polypoidal choroidal vasculopathy is a subtype of exudative ARMD.
- Visible light can result in the formation and accumulation of metabolic by-products in the RPE, a pigment layer underneath the retina that normally helps remove metabolic by-products from the retina. Excess accumulation of these metabolic by-products interferes with the normal metabolic activity of the RPE and can lead to the formation of drusen.
- Neovascular stage generally arises from the atrophic stage.
- Most do not progress beyond the atrophic/nonexudative stage; however, those who do are at a greater risk of severe visual loss.
- Genetic susceptibility may be a factor in ARMD: ~25% genetically determined
- Complement factor H is an important susceptibility gene for ARMD.
- Although the development of ARMD may be predicted by specific alleles, the clinical response to antivascular endothelial growth factor (VEGF) is not.
- Ethnicity: non-Hispanic whites
- Cigarette smoking
- Chlamydia pneumoniae infection
- Family history
- Excess sunlight exposure
- Blue or light iris color
- History of cardiovascular disease
- Short stature
- High plasma high-density lipoprotein cholesterol levels are associated with an increased risk for ARMD.
- Physical activity is associated with lower risk of early and late ARMD in white populations.
- Aspirin use
- Female sex
- Ultraviolet (UV) protection for eyes
- Routine ophthalmologic visits
- Every 2 to 4 years for patients age 40 to 64 years
- Every 1 to 2 years after age 65 years
- Patients who take statins, which modify lipid profiles, may have a reduced risk.
Commonly Associated Conditions
- Presumed ocular histoplasmosis syndrome
- Exudative retinal detachment
- Vitreous hemorrhage
- Other causes of CNVMs