title: Evaluation of acoustic wave propagation velocities in the ocular lens and vitreous tissues of pigs, dogs, and rabbits.
abstract: OBJECTIVE
  To evaluate propagation velocity of acoustic waves through the lens and vitreous body of pigs, dogs, and rabbits and determine whether there were associations between acoustic wave speed and age, temperature, and time after enucleation.
  
  
  METHODS
  9 pig, 40 dog, and 20 rabbit lenses and 16 pig, 17 dog, and 23 rabbit vitreous bodies.
  
  
  METHODS
  Acoustic wave velocities through the ocular structures were measured by use of the substitution technique.
  
  
  RESULTS
  Mean sound wave velocities in lenses of pigs, dogs, and rabbits were 1,681, 1,707, and 1,731 m/s, respectively, at 36 degrees C. Mean sound wave velocities in the vitreous body of pigs, dogs, and rabbits were 1,535, 1,535, and 1,534 m/s, respectively, at 38 degrees C. The sound wave speed through the vitreous humor, but not the lens, increased linearly with temperature. An association between wave speed and age was observed in the rabbit tissues. Time after enucleation did not affect the velocity of sound in the lens or vitreous body. The sound wave speed conversion factors for lenses, calculated with respect to human ocular tissue at 36 degrees C, were 1.024, 1.040, and 1.055 for pig, dog, and rabbit lenses, respectively.
  
  
  CONCLUSIONS
  Conversion factors for the speed of sound through lens tissues are needed to avoid underestimation of the thickness of the lens and axial length of the eye in dogs during comparative A-mode ultrasound examinations. These findings are important for accurate calculation of intraocular lens power required to achieve emmetropia in veterinary patients after surgical lens extraction.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706-1102, USA.
authors.forename: Christiane
authors.initials: C
authors.lastname: Görig
authors.forename: Tomy
authors.initials: T
authors.lastname: Varghese
authors.forename: Timothy
authors.initials: T
authors.lastname: Stiles
authors.forename: Jan
authors.initials: J
authors.lastname: van den Broek
authors.forename: James A
authors.initials: JA
authors.lastname: Zagzebski
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Murphy
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D004285:Dogs; D007908:Lens, Crystalline / Q000502:physiology*; D011817:Rabbits; D013045:Species Specificity; D013552:Swine; D013696:Temperature; D013997:Time Factors; D014463:Ultrasonography / Q000662:veterinary*; D014822:Vitreous Body / Q000502:physiology*