title: Quasielastic light scattering study of the living human lens as a function of age.
abstract: OBJECTIVE
  To determine contributions of molecular scattering elements to the increase with age in the light scattered from the human ocular lens in vivo.
  
  
  METHODS
  We used quasielastic light scattering to measure autocorrelation functions of the intensity of light scattered in vivo from three locations (anterior, nuclear and posterior) along the optic axis in ocular lenses of 225 subjects, ranging from 17 to 63 years of age. We deduced probability distributions of key parameters (Is, If, Ii, IT), which describe contributions of slowly diffusing (Is), rapidly diffusing (If) and relatively immobile (Ii) scattering elements to the total light intensity (IT) scattered into the collection optics. We deduced characteristic time tau s and tau f that describe the Brownian motion of scattering elements.
  
  
  RESULTS
  Probability distributions for each age decile show clearly defined shifts in key parameters with age. IT at the nucleus increases by a factor of three from age 20 to 60 years. This increase is produced principally by an approximate five-fold increase is Is. IT and Is and can be detected with an accuracy of approximately +/- 10%. We estimate threshold values for IT, which mark the boundary beyond which clinical cataract becomes manifest. This boundary represents 6 to 8 times the light scattering efficiency expected from the newborn lens.
  
  
  CONCLUSIONS
  This methodology permits a sensitive, quantitative, clinically useful representation of the pre-cataractous molecular changes associated with aging in the living human lens.
authors.affiliation: Oculon Corporation, Cambridge, MA, USA. george@critical.mit.edu
authors.forename: G M
authors.initials: GM
authors.lastname: Thurston
authors.forename: D L
authors.initials: DL
authors.lastname: Hayden
authors.forename: P
authors.initials: P
authors.lastname: Burrows
authors.forename: J I
authors.initials: JI
authors.lastname: Clark
authors.forename: V G
authors.initials: VG
authors.lastname: Taret
authors.forename: J
authors.initials: J
authors.lastname: Kandel
authors.forename: M
authors.initials: M
authors.lastname: Courogen
authors.forename: J A
authors.initials: JA
authors.lastname: Peetermans
authors.forename: M S
authors.initials: MS
authors.lastname: Bowen
authors.forename: D
authors.initials: D
authors.lastname: Miller
authors.forename: K M
authors.initials: KM
authors.lastname: Sullivan
authors.forename: R
authors.initials: R
authors.lastname: Storb
authors.forename: H
authors.initials: H
authors.lastname: Stern
authors.forename: G B
authors.initials: GB
authors.lastname: Benedek
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D002386:Cataract; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000502:physiology*; D008027:Light; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012542:Scattering, Radiation