Validation of Recalibrated TONOVET Plus and TONOVET Pro in Canine Eyes Compared to Manometer and TONOVET

Abstract

Objective: To evaluate the accuracy of recalibrated TONOVET Plus (rTVP) and the newly released TONOVET Pro (TVPR) in measuring intraocular pressure (IOP) in ex vivo canine eyes compared to manometer and the established TONOVET (TV). Procedure: Sixteen enucleated canine eyes were cannulated to establish manometric IOPs ranging from 5 to 80 mmHg. IOP measurements were obtained using TV, rTVP, and TVPR. Results: All tonometers showed a strong correlation with the manometer (R-2 > 0.98). Measurements from rTVP and TVPR exhibited almost perfect agreement with the manometer (CCC = 0.9974 for both), whereas TV demonstrated lower agreement (CCC = 0.9874) associated with greater systematic bias. Specifically, TV showed a lower proportional bias (95% confidence interval [CI] of the slope = 0.987-1.006) but a larger systematic bias (intercept = -3.33 mmHg) compared to rTVP and TVPR (95% CI of the slope = 1.045-1.066 and 1.045-1.063; intercept = -2.532 and -2.633 mmHg, respectively). In accuracy analyses by range, rTVP and TVPR showed no significant difference from the manometer in the 30-70 mmHg and 35-80 mmHg IOP ranges, respectively. Conclusions: Among the ICare rebound tonometers, rTVP and TVPR provided the most accurate IOP measurements in the ex vivo analysis and demonstrated particularly strong agreement in the high IOP range, suggesting their suitability for IOP measurement in glaucomatous patients.