title: Noninvasive intraocular pressure measurements in mice by pneumotonometry.
abstract: OBJECTIVE
  To develop a reliable, noninvasive, continuous, and easily implemented system for measuring intraocular pressure (IOP) in mice.
  
  
  METHODS
  Pneumotonometry was adapted for measurement of mouse IOP. Measurements were compared with those obtained with the servo-null micropipette system (SNMS) and with direct anterior chamber cannulation. Heart rate was monitored by the precordial pulse, EKG, or tail pulse in anesthetized mice. The characteristic ocular hypotensive response to mannitol was assessed as an additional validation of the
  
  
  METHODS
  
  
  
  RESULTS
  Measurements of IOP obtained using pneumotonometry agreed closely with values measured by SNMS or by direct cannulation. IOP oscillations were synchronous with the heart rate, with a coherence peak between them of approximately 2 Hz, equal to the pulse frequency. Hypertonic mannitol reduced IOP from 13.7 +/- 0.9 mm Hg by 7.7 +/- 0.7 mm Hg after 15 minutes.
  
  
  CONCLUSIONS
  Pneumotonometry is a reliable and noninvasive method for the measurement of IOP in mice and may permit comparisons of IOP to hemodynamic factors. This system is simpler and more adaptable for glaucoma research than previously reported methodologies for measuring IOP in mice.
authors.affiliation: Department of Physiological Sciences, Facultad de Medicina, Universidad Nacional de Colombia, Bogota, Colombia.
authors.forename: Marcel Y
authors.initials: MY
authors.lastname: Avila
authors.forename: Alejandro
authors.initials: A
authors.lastname: Múnera
authors.forename: Arcadio
authors.initials: A
authors.lastname: Guzmán
authors.forename: Chi Wai
authors.initials: CW
authors.lastname: Do
authors.forename: Zhao
authors.initials: Z
authors.lastname: Wang
authors.forename: Richard A
authors.initials: RA
authors.lastname: Stone
authors.forename: Mortimer M
authors.initials: MM
authors.lastname: Civan
mesh_terms: D000818:Animals; D006339:Heart Rate; D007429:Intraocular Pressure / Q000187:drug effects / Q000502:physiology*; D008353:Mannitol / Q000008:administration & dosage; D051379:Mice; D008810:Mice, Inbred C57BL; D015814:Ocular Hypotension / Q000139:chemically induced / Q000503:physiopathology; D015203:Reproducibility of Results; D014065:Tonometry, Ocular / Q000379:methods*
chemical_list: D008353:Mannitol