title: Viscoelastic shear properties of the fresh porcine lens.
abstract: OBJECTIVE
  To determine the viscoelastic properties of the porcine lens
  
  
  METHODS
  Linear viscoelastic shear properties of the stroma of four porcine lenses were measured within 5 hours post-mortem, using sinusoidal oscillatory shear deformation. The elastic shear modulus, viscous shear modulus, dynamic viscosity, damping ratio, and phase shift of the lenses were quantified by a controlled-strain, linear simple-shear rheometer at frequencies of 10-50 Hz.
  
  
  RESULTS
  The mean viscoelastic properties and their standard deviations across the frequencies examined were: the elastic shear modulus, G' = 6.2+/-4.0 Pa, the viscous shear modulus, G'' = 19.2+/-2.5 Pa, the dynamic viscosity, eta' = 0.16+/-0.1 Pa x sec, the damping ratio zeta = 4.06+/-1.25, and the phase shift, delta = 76 degrees +/- 5.6 degrees.
  
  
  CONCLUSIONS
  The measured viscoelastic shear properties of the porcine lens reflect a low dynamic viscosity with a high damping ratio. The porcine lens is viscoelastic and is more viscous than elastic. The magnitude of the complex shear modulus of the porcine lens, |G*|, is similar to the shear modulus of the young human lens. Understanding these viscoelastic properties of the natural lens may provide guidance in developing a lens substitute capable of accommodation in the post cataract patient.
authors.affiliation: Department of Physics, University of Arlington, Arlington, Texas, USA. ron@2ras.com
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Schachar
authors.forename: Roger W
authors.initials: RW
authors.lastname: Chan
authors.forename: Min
authors.initials: M
authors.lastname: Fu
mesh_terms: D000818:Animals; D004548:Elasticity; D007908:Lens, Crystalline / Q000502:physiology*; D033081:Shear Strength; D013314:Stress, Mechanical; D013552:Swine / Q000502:physiology*; D014783:Viscosity