Evaluation of rebound tonometry in non-human primates

Area of Science:

• Veterinary Ophthalmology
• Primate Research
• Ophthalmic Instrumentation

Background:

• Intraocular pressure (IOP) measurement is crucial in veterinary ophthalmology, particularly in non-human primates used in research.
• Accurate and reproducible IOP assessment is essential for monitoring ocular health and disease in cynomolgus macaques.
• The TonoVet® rebound tonometer offers potential advantages in ease of use and portability for IOP measurements.

Purpose of the Study:

• To evaluate the accuracy and reproducibility of the TonoVet® rebound tonometer for measuring IOP in anesthetized cynomolgus macaques.
• To investigate the influence of central corneal thickness on TonoVet® IOP measurements in this species.
• To compare TonoVet® readings with manometric IOP and Goldmann applanation tonometry.

Main Methods:

• Anesthetized cynomolgus macaques underwent IOP manipulation via a cannulated anterior chamber connected to a reservoir and transducer.
• IOP was measured using the TonoVet® and 'minified' Goldmann applanation tonometry at various pressure increments and decrements.
• Central corneal thickness was measured using ultrasonic pachymetry; readings were taken by multiple observers.

Main Results:

• TonoVet® readings demonstrated a strong correlation with manometric IOP (r² = 0.955).
• No significant differences in accuracy were found between eyes or observers, though a trend favored right eyes.
• TonoVet® readings during the decremental phase were significantly more accurate than during the incremental phase (p < 0.004).

Conclusions:

• The TonoVet® rebound tonometer is a reliable and accurate instrument for measuring IOP in cynomolgus macaques.
• Its portability, ease of use, and minimal corneal contact make it advantageous, potentially eliminating the need for topical anesthetics.
• The device provides consistent IOP measurements, supporting its use in primate ophthalmic research.