Comparative intraocular pressure measurements using three different rebound tonometers through in an ex vivo analysis and clinical trials in canine eyes.

Abstract

OBJECTIVE: To evaluate the clinical relevance of intraocular pressure (IOP) measured with three different rebound tonometers in an ex vivo analysis and clinical trials in dogs. ANIMALS AND PROCEDURES: Ex vivo analysis and clinical trials were performed separately. For the ex vivo analysis, eight enucleated eyes were obtained from four Beagle dogs. IOP values measured with TONOVET(TV-IOP), TONOVET-Plus(TVP-IOP), and SW-500(SW-IOP) were compared with manometric IOPs. For clinical trials, each tonometer was evaluated separately, depending on whether TVP-IOP was higher or lower than 14 mm Hg. One-way repeatedmeasures analysis of variance, simple linear regression analysis, and Bland-Altman plots were used for statistical analyses. RESULTS: In ex vivo analysis, TV-IOP and TVP-IOP were not significantly different from manometric IOP. However, SW-IOP underestimated IOP compared to manometry. Higher discrepancy was observed in TV-IOP and SW-IOP with an increase in manometric IOP. In clinical trials, no significant difference was observed between TV-IOP (9.73 ± 2.92) and TVP-IOP (11.36 ± 2.23) when TVP-IOP was lower than 14 mm Hg, but SW-IOP (8.70 ± 3.03) was significantly lower than TVP-IOP. TV-IOP (15.96 ± 6.47) and SW-IOP (13.09 ± 3.72) were significantly lower than TVP-IOP (20.08 ± 6.60) when the IOP was higher than 14 mm Hg of TVP-IOP. CONCLUSIONS: This study demonstrates that the TONOVETand TONOVET-Plusprovide a useful approach for ex vivo analysis. In clinical trials, results of TV-IOP and SW-IOP were significantly lower than of TVP-IOP when IOP was higher than 14 mm Hg of TVP-IOP. The characteristics of rebound tonometers should be considered in clinical settings.