Age-related macular degeneration

Age-related macular degeneration is a potentially progressive maculopathy.

Characterized by drusen formation, macular pigmentary changes, geographic atrophy, and neovascularization of the choriocapillaris with exudation.

Sudden-onset of blurring or distortion of vision is often the presenting symptom in the neovascular form.

Leading cause of adult blindness in industrialized nations.

Typically affects people aged >55 years.

Diagnosis and treatment are highly specialized and involve consultation with a retinal specialist.

Age-related macular degeneration (AMD) is a potentially progressive maculopathy.[1]Arnold JJ. Age-related macular degeneration: anti-vascular endothelial growth factor treatment. BMJ Clin Evid. 2016 Feb 24;2016:0701. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4765776 http://www.ncbi.nlm.nih.gov/pubmed/26909890?tool=bestpractice.com It is characterized by distinct clinical stages including early and intermediate AMD with drusen (yellow deposits under the retina made up of lipids and proteins) and macular pigmentary changes, usually associated with normal or near-normal vision; and late AMD, which is associated with a decrease or loss of central vision. Late (or advanced) AMD has two forms: geographic atrophy (or “atrophic” or “dry” AMD) and neovascular AMD (or “wet” or "exudative” AMD).[2]Ferris FL 3rd, Wilkinson CP, Bird A, et al; Beckman Initiative for Macular Research Classification Committee. Clinical classification of age-related macular degeneration. Ophthalmology. 2013 Apr;120(4):844-51. http://www.ncbi.nlm.nih.gov/pubmed/23332590?tool=bestpractice.com Geographic atrophy is a chronic progressive degeneration of the macula; degeneration commences at the level of the retinal pigment epithelium, which is lost in the late stages with associated thinning and degeneration of the neurosensory retina. Choroidal neovascularization refers to the abnormal growth of blood vessels from the vascular layer of the eye (choroid) to the neurosensory retina. 

People with small drusen (<63 micrometers), also termed drupelets, are considered to have normal aging changes. People with medium-sized drusen (≥63 to <125 micrometers) in the absence of pigmentary changes are defined as having early AMD. People with large drusen (≥125 micrometers) or pigmentary abnormalities and at least medium-sized drusen are defined as having intermediate AMD.

Five-year risks of progressing to late AMD are estimated to increase from 0.5% for normal aging changes up to 50% risk for intermediate AMD.[2]Ferris FL 3rd, Wilkinson CP, Bird A, et al; Beckman Initiative for Macular Research Classification Committee. Clinical classification of age-related macular degeneration. Ophthalmology. 2013 Apr;120(4):844-51. http://www.ncbi.nlm.nih.gov/pubmed/23332590?tool=bestpractice.com

In addition, reticular pseudodrusen (small drusen-like deposits that form between the photoreceptors and retinal pigment epithelium) are now recognized as precursors to both forms of late AMD.[3]Zhou Q, Daniel E, Maguire MG, et al. Pseudodrusen and incidence of late age-related macular degeneration in fellow eyes in the comparison of age-related macular degeneration treatments trials. Ophthalmology. 2016 Jul;123(7):1530-40. https://www.aaojournal.org/article/S0161-6420(16)00330-4/fulltext http://www.ncbi.nlm.nih.gov/pubmed/27040149?tool=bestpractice.com [4]Suzuki M, Sato T, Spaide RF. Pseudodrusen subtypes as delineated by multimodal imaging of the fundus. Am J Ophthalmol. 2014 May;157(5):1005-12. https://www.ajo.com/article/S0002-9394(14)00055-5/fulltext http://www.ncbi.nlm.nih.gov/pubmed/24503406?tool=bestpractice.com