Neovascular Age-Related Macular Degeneration
Age-related macular degeneration (AMD) is the most common cause of visual impairment in patients older than of 55 years in industrialized countries.1
Neovascular AMD (NVAMD) is characterized by growth of abnormal blood vessels (neovascularization) originating from the choroid or retina, leading to hemorrhage, exudation, and subretinal scarring and subsequent vision loss.
The historical gold standard for initial diagnosis of choroidal neovascularization (CNV) in NVAMD is fluorescein angiography (FA). CNV may be classified as classic or occult based on the fluorescence pattern.
Classic CNV shows an early well-demarcated area of hyperfluorescence that progressively increases in size and intensity.
Occult CNV shows a mid-phase or late-phase speckled hyperfluorescence with or without progressive leakage.
However, optical coherence tomography (OCT) has become the most common test for diagnosing NVAMD and associated exudation with optical coherence tomography angiography (OCTA) also increasing in popularity for identifying neovascularization.
An OCT-based CNV classification system has also been described.
Type 1: new vessel growth from under the retinal pigment epithelium (RPE).
Type 2: new vessel proliferation between the RPE and neurosensory retina.
Type 3: new vessel proliferation originating from within the retina with anastomoses with choroidal circulation (also known as retinal angiomatous proliferation [RAP]).
Characteristic finding of AMD includes drusen, which are seen as RPE elevations with sub-RPE material.
The transition to NVAMD is heralded by the development of intraretinal fluid and/or subretinal fluid, reflective of active exudation (Figures 23.1, 23.2, 23.3).
NVAMD OCT findings may include RPE detachments (pigment epithelial detachment [PED]), RPE tears, subretinal fluid, intraretinal fluid, and fibrovascular scarring (Figures 23.1 and 23.2).2
Type 1 CNV (occult CNV) may present as thickened elevated RPE or a PED with serous or fibrovascular sub-RPE material.
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