title: In Vivo Brillouin Analysis of the Aging Crystalline Lens.
abstract: OBJECTIVE
  To analyze the age dependence of the longitudinal modulus of the crystalline lens in vivo using Brillouin scattering data in healthy subjects.
  
  
  METHODS
  Brillouin scans were performed along the crystalline lens in 56 eyes from 30 healthy subjects aged from 19 to 63 years. Longitudinal elastic modulus was acquired along the sagittal axis of the lens with a transverse and axial resolution of 4 and 60 μm, respectively. The relative lens stiffness was computed, and correlations with age were analyzed.
  
  
  RESULTS
  Brillouin axial profiles revealed nonuniform longitudinal modulus within the lens, increasing from a softer periphery toward a stiffer central plateau at all ages. The longitudinal modulus at the central plateau showed no age dependence in a range of 19 to 45 years and a slight decrease with age from 45 to 63 years. A significant intersubject variability was observed in an age-matched analysis. Importantly, the extent of the central stiff plateau region increased steadily over age from 19 to 63 years. The slope of change in Brillouin modulus in the peripheral regions were nearly age-invariant.
  
  
  CONCLUSIONS
  The adult human lens showed no measurable age-related increase in the peak longitudinal modulus. The expansion of the stiff central region of the lens is likely to be the major contributing factor to age-related lens stiffening. Brillouin microscopy may be useful in characterizing the crystalline lens for the optimization of surgical or pharmacological treatments aimed at restoring accommodative power.
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States 2Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Sebastien
authors.initials: S
authors.lastname: Besner
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States 2Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States 3Fischell Department of Bioengineering, University of Maryland, College Park, Maryland, United States.
authors.forename: Giuliano
authors.initials: G
authors.lastname: Scarcelli
authors.affiliation: Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts, United States.
authors.forename: Roberto
authors.initials: R
authors.lastname: Pineda
authors.affiliation: Wellman Center for Photomedicine, Massachusetts General Hospital, Cambridge, Massachusetts, United States 2Department of Dermatology, Harvard Medical School, Boston, Massachusetts, United States 5Harvard-MIT Health Sciences and Technology, Cambridge, Massachusetts, United States.
authors.forename: Seok-Hyun
authors.initials: SH
authors.lastname: Yun
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology; D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D002648:Child; D055119:Elastic Modulus; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000166:cytology / Q000502:physiology*; D008297:Male; D018613:Microscopy, Confocal; D008875:Middle Aged; D013314:Stress, Mechanical; D055815:Young Adult