Epidemiology

AMD is the leading cause of blindness in individuals > 65 years in developed countries.
- Age of onset: usually > 55 years

Etiology

AMD is characterized by progressive degenerative changes in the central part of the retina (macula) → visual impairment.

Dry AMD (∼ 90%)
- Also referred to as nonexudative AMD or atrophic AMD
- Deposition of yellow-whitish material consisting of lipids, vitronectin, and other proteins (drusen) in the retinal pigment epithelium and between it and Bruch membrane → slow progressive atrophy of the local retinal pigment epithelium (centrally or pericentrally)
Wet AMD (∼ 10%)
- Also referred to as exudative AMD or neovascular AMD
- Choroidal neovascularization (between the retinal pigment epithelium and Bruch’s membrane) → leaking of intravascular serous fluid and blood → sudden localized elevation of the macula and/or detachment of the retinal pigment epithelium
  - Hemorrhages can cause sudden loss of vision.

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Painless central or pericentral visual impairment → reduced visual acuity, difficulty adapting to changes in lighting
- Dry AMD: slow progressive visual impairment (usually over decades) and unilateral or bilateral onset
- Wet AMD: acute or insidious onset (over weeks to months) and usually manifests in one eye first
Metamorphopsia: type of visual distortion in which straight lines appear wavy, which can be tested for using an Amsler grid
Scotoma (blind spot)

Amsler grid: detection of metamorphopsias and scotomas
Fundoscopy
- Dry AMD
  - Drusen
- Wet AMD
  - Subretinal and intraretinal hemorrhage and/or exudate

Treatment of wet AMD
- First-line: injection of VEGF inhibitors (ranibizumab, bevacizumab, pegaptanib) into the vitreous body

Mnemonic

Ranibizumab → bizu 两个眼珠