title: Characterization of Choroidal Layers in Normal Aging Eyes Using Enface Swept-Source Optical Coherence Tomography.
abstract: OBJECTIVE
  To characterize qualitative and quantitative features of the choroid in normal eyes using enface swept-source optical coherence tomography (SS-OCT).
  
  
  METHODS
  Fifty-two eyes of 26 consecutive normal subjects were prospectively recruited to obtain multiple three-dimensional 12 x 12 mm volumetric scans using a long-wavelength high-speed SS-OCT prototype. A motion-correction algorithm merged multiple SS-OCT volumes to improve signal. Retinal pigment epithelium (RPE) was segmented as the reference and enface images were extracted at varying depths every 4.13 μm intervals. Systematic analysis of the choroid at different depths was performed to qualitatively assess the morphology of the choroid and quantify the absolute thicknesses as well as the relative thicknesses of the choroidal vascular layers including the choroidal microvasculature (choriocapillaris, terminal arterioles and venules; CC) and choroidal vessels (CV) with respect to the subfoveal total choroidal thickness (TC). Subjects were divided into two age groups: younger (<40 years) and older (≥ 40 years).
  
  
  RESULTS
  Mean age of subjects was 41.92 (24-66) years. Enface images at the level of the RPE, CC, CV, and choroidal-scleral interface were used to assess specific qualitative features. In the younger age group, the mean absolute thicknesses were: TC 379.4 μm (SD ± 75.7 μm), CC 81.3 μm (SD ± 21.2 μm) and CV 298.1 μm (SD ± 63.7 μm). In the older group, the mean absolute thicknesses were: TC 305.0 μm (SD ± 50.9 μm), CC 56.4μm (SD ± 12.1 μm) and CV 248.6μm (SD ± 49.7 μm). In the younger group, the relative thicknesses of the individual choroidal layers were: CC 21.5% (SD ± 4.0%) and CV 78.4% (SD ± 4.0%). In the older group, the relative thicknesses were: CC 18.9% (SD ± 4.5%) and CV 81.1% (SD ± 4.5%). The absolute thicknesses were smaller in the older age group for all choroidal layers (TC p=0.006, CC p=0.0003, CV p=0.03) while the relative thickness was smaller only for the CC (p=0.04).
  
  
  CONCLUSIONS
  Enface SS-OCT at 1050 nm enables a precise qualitative and quantitative characterization of the individual choroidal layers in normal eyes. Only the CC is relatively thinner in the older eyes. In-vivo evaluation of the choroid at variable depths may be potentially valuable in understanding the natural history of age-related posterior segment disease.
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America; Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Mehreen
authors.initials: M
authors.lastname: Adhi
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Daniela
authors.initials: D
authors.lastname: Ferrara
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States of America.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Mullins
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Caroline R
authors.initials: CR
authors.lastname: Baumal
authors.affiliation: Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Faculty of Physics, Ludwig-Maximilians-University Munich, Munich, Germany.
authors.forename: Kathrin J
authors.initials: KJ
authors.lastname: Mohler
authors.affiliation: Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America; Pattern Recognition Lab and Graduate School in Advanced Optical Technologies, University Erlangen-Nuremburg, Erlangen-Nuremburg, Germany.
authors.forename: Martin F
authors.initials: MF
authors.lastname: Kraus
authors.affiliation: Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Emmerson
authors.initials: E
authors.lastname: Badaro
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Tarek
authors.initials: T
authors.lastname: Alasil
authors.affiliation: Pattern Recognition Lab and Graduate School in Advanced Optical Technologies, University Erlangen-Nuremburg, Erlangen-Nuremburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Hornegger
authors.affiliation: Department of Electrical Engineering and Computer Science and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: James G
authors.initials: JG
authors.lastname: Fujimoto
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Duker
authors.affiliation: Department of Ophthalmology, New England Eye Center, Tufts Medical Center, Boston, Massachusetts, United States of America.
authors.forename: Nadia K
authors.initials: NK
authors.lastname: Waheed
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D002829:Choroid / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D055806:Microvessels / Q000502:physiology; D008875:Middle Aged; D011446:Prospective Studies; D055213:Retinal Pigment Epithelium / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology; D012590:Sclera / Q000033:anatomy & histology* / Q000098:blood supply / Q000502:physiology*; D041623:Tomography, Optical Coherence / Q000379:methods; D055815:Young Adult