title: Evaluation of rebound tonometry in red-eared slider turtles (Trachemys scripta elegans).
abstract: OBJECTIVE
  To evaluate feasibility and accuracy of intraocular pressure (IOP) measurement by rebound tonometry in adult red-eared slider turtles and determine the effects of manual and chemical restraint on IOP.
  
  
  METHODS
  Seventeen adult red-eared slider turtles.
  
  
  METHODS
  Intraocular pressure was measured with TonoLab® and TonoVet® tonometers in conscious, unrestrained turtles. To evaluate the effects of manual restraint, turtles were restrained by digital pressure on the rostral head or proximal neck. The effect of two chemical restraint protocols (dexmedetomidine, ketamine, midazolam [DKM] and dexmedetomidine, ketamine [DK] subcutaneously) on IOP was evaluated. Triplicate TonoLab® and TonoVet® readings were compared with direct manometry in three ex vivo turtle eyes.
  
  
  RESULTS
  TonoLab® correlated better with manometry at IOPs < 45 mmHg than TonoVet® (linear regression slopes of 0.89 and 0.30, respectively). Mean (±SD) IOP in unrestrained conscious turtles was significantly lower (P < 0.01) with TonoLab® (10.02 ± 0.66 mmHg) than with TonoVet® (11.32 ± 1.57 mmHg). Manual neck restraint caused a significant increase in IOP (+6.31 ± 5.59 mmHg), while manual rostral head restraint did not. Both chemical restraint protocols significantly reduced IOP (DKM: −1.0 ± 0.76 mmHg; DK: −1.79 ± 1.17) compared with measurements in conscious unrestrained turtles.
  
  
  CONCLUSIONS
  Chemical and manual neck restraint affected IOP. Rostral head restraint had no significant effect on IOP and is, therefore, recommended as the appropriate restraint technique in red-eared slider turtles. TonoLab® measurements estimated actual IOP more accurately, within physiologic range, than measurements obtained using the TonoVet®.
authors.affiliation: Department of Surgical Sciences, School of Veterinary Medicine, 2015 Linden Drive, Madison, WI 53706, USA.  cherlenedelgado@gmail.com
authors.forename: Cherlene
authors.initials: C
authors.lastname: Delgado
authors.forename: Christoph
authors.initials: C
authors.lastname: Mans
authors.forename: Gillian J
authors.initials: GJ
authors.lastname: McLellan
authors.forename: Ellison
authors.initials: E
authors.lastname: Bentley
authors.forename: Kurt K
authors.initials: KK
authors.lastname: Sladky
authors.forename: Paul E
authors.initials: PE
authors.lastname: Miller
mesh_terms: D000818:Animals; D007429:Intraocular Pressure / Q000502:physiology*; D014065:Tonometry, Ocular / Q000662:veterinary*; D014426:Turtles / Q000502:physiology*
keywords: TonoLab®; TonoVet®; intraocular pressure; manometry; rebound tonometry; turtle
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