Comparison of the Effects of Different TonoVet® Plus Modes on Intraocular Pressure Measurements in Healthy Domestic Pigeons (Columba livia)

Objective: The aim of this study was to systematically evaluate Intraocular pressure (IOP) measurements in healthy, conscious domestic pigeons using the four available animal modes on the TonoVet® Plus device. Materials and Methods: Seventy eyes of 35 healthy pigeons were included in the study. IOP measurements were performed in conscious animals, without anesthesia, using the four modes of the TonoVet® Plus device in a randomized order Results: Measurement mode had a statistically significant effect on IOP (p 0.05). Mean IOP ranged from 8.59±2.22 mmHg for the Cat mode to 15.57±2.04 mmHg for the Rabbit mode. All modes demonstrated excellent reliability (ICC 0.88), with the Cat mode having the highest (ICC=0.931) and the Rabbit mode the lowest (ICC=0.882). Compared to the calibrated reference value in the literature, the Rabbit mode provided the result closest to the lower limit of the reference range, while the most reliable Cat mode significantly underestimated IOP. Conclusion: None of the available modes in TonoVet® Plus are ideal for pigeons, and mode selection significantly influences the results. The Cat mode, with its highest reliability, is preferred for monitoring IOP changes, while the Rabbit mode, with its highest apparent accuracy, is preferred for scanning against the reference range. However, in both cases, results should be interpreted cautiously within the limitations of the mode. Direct manometric calibration of TonoVet® Plus for pigeons and the development of a species-specific mode are needed.