Validation of the Reichert® Tono‐Vera® Vet rebound tonometer in normal ex vivo canine eyes

Objective To determine the accuracy of the Reichert® Tono‐Vera® Vet rebound tonometer for canine intraocular pressure (IOP) measurement. Animals Studied Five normal canine ex vivo globes. Procedures The anterior chambers of five freshly enucleated normal canine eyes were cannulated and connected to a reservoir of Plasma‐Lyte A and a manometer. Starting at a manometric IOP of 5 mmHg, the pressure was progressively increased to 80 mmHg by raising the reservoir. Triplicate IOP measurements were taken with the Tono‐Vera® Vet from the central cornea using the dog setting and compared to the manometric pressure by linear regression analysis and Bland–Altman plots. Results There was a strong positive linear regression trend when comparing central corneal Tono‐Vera® Vet IOPs to manometric pressures (r2 = .99) with solid agreement between the two methods. Compared to manometric IOPs, the Tono‐Vera® Vet underestimated IOPs at higher pressures ≥70 mmHg. Conclusions Measurement of IOPs from the central cornea with the Tono‐Vera® Vet provided accurate results over a large range in normal canine globes compared to direct manometry. The mild to moderate underestimation of IOPs at high pressures was not considered clinically relevant.