Age-Related Macular Degeneration

Age-related macular degeneration (AMD), the leading cause of legal blindness in people 65 years or older in the United States,¹ is a degenerative disorder of the retinal pigment epithelium (RPE) and neurosensory retina. The macula is the portion of the central retina with the greatest concentration of photoreceptors and provides high-resolution visual acuity. The early stages of AMD are characterized clinically by the development of soft drusen associated with pigmentary abnormalities of the RPE and retina (Figure 1A). Drusen, accumulations of amorphous, acellular debris within the basement membrane of the RPE, are seen ophthalmoscopically as yellow spots within the macula.² While small drusen are commonly present in the macula as a consequence of aging, the presence of large and numerous drusen is associated with AMD.³ Late-stage AMD is characterized by the development of well-defined areas of RPE loss (geographic atrophy) (Figure 1B), choroidal neovascularization (CNV) (Figure 1C), pigment epithelial detachment, and fibrous scarring of the macula (disciform scarring).^2,4 The presence of soft drusen, pigmentary abnormalities, and geographic atrophy is commonly termed dry (nonneovascular) AMD. The development of CNV, pigment epithelial detachment, or disciform scarring is an exudative process and commonly termed wet (neovascular) AMD. The wet form of AMD comprises approximately 15% of the cases,⁵ but because of its severity, accounts for the majority of severe visual loss due to AMD.⁶