Abstract

Background:
Precise intraocular pressure (IOP) quantification is pivotal for investigating glaucoma pathophysiology and establishing reliable animal models.

Aim:
This study comprehensively evaluated the accuracy, precision, and reproducibility of the novel iFalcon™ V100 rebound tonometer using ex vivo and in vivo feline models, referenced against intracameral manometry.

Methods:
Four ex vivo feline eyes and one in vivo subject were included. In the ex vivo phase, IOP was hydrostatically modulated between 5 and 75 mmHg via anterior chamber cannulation. Simultaneous readings were recorded from the iFalcon™ V100 and the reference pressure transducer. Agreement was assessed using linear regression, Bland-Altman analysis, and stratified box plots. In the in vivo phase, bilateral measurements were performed by two independent operators using both the iFalcon™ V100 and an iCare tonometer (Tonovet) to evaluate inter-operator reproducibility and inter-device comparability.

Results:
Linear regression analysis revealed a strong positive correlation between iFalcon™ V100 readings and manometry. Although a slight proportional bias (slope > 1.0) was observed in the high-IOP range—attributed to feline corneal biomechanics—the device maintained excellent linearity. Bland-Altman analysis demonstrated high measurement accuracy with a mean bias of only 0.41 mmHg and 95% limits of agreement (LoA) ranging from -4.17 to 5.00 mmHg. Stratified analysis indicated robust stability within the high-pressure challenge range (30–70 mmHg); however, data acquisition rates decreased during hypotony ( 0.05) and demonstrated high consistency with the iCare tonometer.

Conclusion:
The iFalcon™ V100 rebound tonometer exhibits sub-mmHg mean accuracy and a wide-range linear response in feline models. Despite a minor species-specific proportional bias, its superior repeatability and inter-operator stability validate its utility as a reliable, non-invasive tool for feline ophthalmic research and longitudinal glaucoma monitoring.

Key words: Intraocular pressure; iFalcon™ V100; Rebound tonometer; Feline model.