Intraocular pressure reference intervals in eyes of clinically normal miniature donkeys (Equus africanus asinus).

The research article investigates and establishes reference intervals for intraocular pressure in healthy miniature donkeys, and finds that rebound tonometry methods yield significantly higher readings than applanation tonometry methods.

Objective of the Research

• This study aims to identify and establish intraocular pressure (IOP) reference intervals, key benchmarks for eye health, in healthy miniature donkeys. The research team used both rebound and applanation tonometry – two distinctive methods for measuring IOP.

Methodology

• Both full ophthalmic and physical exams were performed by board-certified veterinary ophthalmologists on each of the donkeys included in the study.
• Donkeys were selected based on the criteria outlined by the American Society for Veterinary Clinical Pathology (ASVCP) reference interval guidelines. The IOP levels were estimated using TonoVet and TonoPen XL tools.
• Two groups were formed for the research. Forty animals, known as the San Angelo group, received intramuscular xylazine hydrochloride 10% and auriculopalpebral (AP) nerve blocks before obtaining measurements. The Austin group, comprised of twenty-two animals, received no sedation or AP block.
• Data was analyzed following ASVCP reference interval guidelines with statistical analysis done using sas V9 software.

Results

• Fifty-seven healthy miniature donkeys, accounting for 114 eyes, were included in the study.
• The mean IOP was found to be 25.75 ± 5.70 mm Hg for rebound tonometry and 20.69 ± 5.06 mm Hg for applanation tonometry.
• The study found no significant difference in IOP between the San Angelo group and Austin group, indicating that the sedation or AP block didn’t influence the results.
• The study did find a significant disparity between IOP estimates obtained from rebound tonometry versus applanation tonometry, with rebound measurements being consistently higher.

Conclusions

• The research successfully established reference intervals for intraocular pressure in healthy miniature donkeys. These reference intervals serve as an invaluable resource for veterinarians and researchers when checking for eye health in this particular species.
• It was found that different methods of measuring IOP can yield significantly different results. In particular, readings from the rebound tonometer were notably higher than those from applanation.
• It was also concluded that sedation and AP block did not influence the measurement of IOP, allowing for more consistent standards for future research and clinical practice.