Related Experiment Video
Updated: Feb 13, 2026

Use of Rabbit Eyes in Pharmacokinetic Studies of Intraocular Drugs
Published on: July 23, 2016
Intraocular pressure reference intervals in eyes of clinically normal miniature donkeys (Equus africanus asinus)
Carla D Hibbs1, Paul M Barrett1, D Dustin Dees2
1Eye Care for Animals, El Paso, TX, USA.
Purpose:
To determine intraocular pressure (IOP) reference intervals in eyes of healthy miniature donkeys (Equus africanus asinus) via rebound and applanation tonometry.
Methods:
Complete ophthalmic and physical examinations were performed by board-certified veterinary ophthalmologists. Inclusion criteria for animals participating in this study were dictated by the American Society for Veterinary Clinical Pathology (ASVCP) reference interval guidelines. Intraocular pressure estimates (TonoVet® and TonoPen XL® ) were obtained in both eyes. Forty animals (San Angelo group) received intramuscular xylazine hydrochloride 10% and auriculopalpebral (AP) nerve blocks prior to obtaining measurements. Twenty-two animals (Austin group) received no sedation or AP block. Statistical analysis followed ASVCP reference interval guidelines. Analysis was performed using the software sas V9 (SAS Institute Inc., Cary, NC, USA).
Results:
Fifty-seven (114 eyes) healthy miniature donkeys were included in this study. The mean IOP ± standard deviation (SD) was 25.75 ± 5.70 mm Hg for rebound tonometry with reference limits of 14.34 and 37.15. The mean IOP ± SD was 20.69 ± 5.06 mm Hg for applanation tonometry with reference limits of 12.82 and 33.38. No significant difference in IOP was found between the Austin and San Angelo groups (P = .34). A significant difference was noted between rebound and applanation IOP estimates (P < .0001) with rebound tonometric values being higher.
Conclusions:
Reference intervals for IOP's were established for this species. Intraocular pressure readings obtained by the rebound tonometer were significantly higher than with applanation. Sedation and AP block did not affect IOP estimates.
Related Concept Videos
Prediction Intervals
However, the point estimate is most likely not the exact value of the population parameter, but close to it. After calculating point estimates, we construct interval estimates, called confidence intervals or prediction intervals. This prediction interval comprises a range of values unlike the point estimate and is a better predictor of the observed sample value, y.
Confidence Intervals
A...
Inertial Frames of Reference
Non-inertial Frames of Reference
Improper Integrals: Infinite Intervals
Vapor Pressure

