title: Quantitative autofluorescence and cell density maps of the human retinal pigment epithelium.
abstract: OBJECTIVE
  Lipofuscin (LF) accumulation within RPE cells is considered pathogenic in AMD. To test whether LF contributes to RPE cell loss in aging and to provide a cellular basis for fundus autofluorescence (AF) we created maps of human RPE cell number and histologic AF.
  
  
  METHODS
  Retinal pigment epithelium-Bruch's membrane flat mounts were prepared from 20 donor eyes (10 ≤ 51 and 10 > 80 years; postmortem: ≤4.2 hours; no retinal pathologies), preserving foveal position. Phalloidin-binding RPE cytoskeleton and LF-AF (488-nm excitation) were imaged at up to 90 predefined positions. Maps were assembled from 83,330 cells in 1470 locations. From Voronoi regions representing each cell, the number of neighbors, cell area, and total AF intensity normalized to an AF standard was determined.
  
  
  RESULTS
  Highly variable between individuals, RPE-AF increases significantly with age. A perifoveal ring of high AF mirrors rod photoreceptor topography and fundus-AF. Retinal pigment epithelium cell density peaks at the fovea, independent of age, yet no net RPE cell loss is detectable. The RPE monolayer undergoes considerable lifelong re-modeling. The relationship of cell size and AF, a surrogate for LF concentration, is orderly and linear in both groups. Autofluorescence topography differs distinctly from the topography of age-related rod loss.
  
  
  CONCLUSIONS
  Digital maps of quantitative AF, cell density, and packing geometry provide metrics for cellular-resolution clinical imaging and model systems. The uncoupling of RPE LF content, cell number, and photoreceptor topography in aging challenges LF's role in AMD.
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ach
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Carrie
authors.initials: C
authors.lastname: Huisingh
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States University of Alabama at Birmingham, Department of Epidemiology, Birmingham, Alabama, United States.
authors.forename: Gerald
authors.initials: G
authors.lastname: McGwin
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Messinger
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: University of Alabama at Birmingham, Department of Computer and Information Sciences, Birmingham, Alabama, United States.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Bentley
authors.affiliation: Center for Coastal Studies, Texas A&M University-Corpus Christi, Corpus Christi, Texas, United States.
authors.forename: Danielle B
authors.initials: DB
authors.lastname: Gutierrez
authors.affiliation: Medical University of South Carolina, Department of Ophthalmology, Charleston, South Carolina, United States.
authors.forename: Zsolt
authors.initials: Z
authors.lastname: Ablonczy
authors.affiliation: New York University School of Medicine, Department of Ophthalmology, New York, New York, United States.
authors.forename: R Theodore
authors.initials: RT
authors.lastname: Smith
authors.affiliation: University of Alabama at Birmingham, Department of Computer and Information Sciences, Birmingham, Alabama, United States.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Sloan
authors.affiliation: University of Alabama at Birmingham, Department of Ophthalmology, Birmingham, Alabama, United States.
authors.forename: Christine A
authors.initials: CA
authors.lastname: Curcio
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D018450:Disease Progression; D005260:Female; D006801:Humans; D008062:Lipofuscin / Q000493:pharmacokinetics; D008268:Macular Degeneration / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008856:Microscopy, Fluorescence / Q000379:methods; D008875:Middle Aged; D061848:Optical Imaging / Q000379:methods*; D055213:Retinal Pigment Epithelium / Q000378:metabolism / Q000473:pathology*
chemical_list: D008062:Lipofuscin
keywords: autofluorescence; cytoskeleton; lipofuscin; photoreceptor; retinal pigment epithelium