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.

Validation of the eyeTelemed IOPvet indentation tonometer for use in dogs.

OBJECTIVE: To assess the accuracy of canine intraocular pressure (IOP) estimates from the eyeTelemed IOPvet indentation tonometer. ANIMALS STUDIED: Part 1 included 54 eyes from 28 Beagle dogs-23 ADAMTS10-mutants with open-angle glaucoma and 5 normals. Part 2 involved five normal canine ex vivo globes. PROCEDURE: Part 1 (in vivo) compared IOPvet estimates in normal and glaucomatous dogs to Reichert Tono-Vera® Vet rebound tonometry. The three IOPvet estimates were green (normal; <20 mmHg, according to the manufacturer), yellow (elevated; 20-30 mmHg), and red (high; >30 mmHg). In Part 2 (ex vivo), the pressure inside freshly enucleated normal canine eyes was progressively increased from 5 to 80 mmHg and compared to IOPvet estimates. Descriptive statistics compared IOPvet estimates to rebound tonometry and direct manometry, with the threshold from normal to glaucoma set at 30 mmHg. RESULTS: In Part 1 (in vivo), normal pressures (≤30 mmHg) were mainly identified correctly as green or yellow-110 of 111 estimates, corresponding to a specificity of 99%. Only 16 of 125 affected estimates were correctly displayed in the >30-mmHg range; the remaining 109 showed ≤30 mmHg, corresponding to a sensitivity of 13%. In Part 2 (ex vivo), all normal pressures were correctly estimated with green, but 64 of 88 manometric IOPs >30 mmHg were falsely estimated as 20-30 mmHg. CONCLUSIONS: The IOPvet is inaccurate in estimating canine IOP with a low sensitivity at identifying dogs with IOP > 30 mmHg. Canine-specific instrument revision is required to correctly identify elevated (yellow = 20-30 mmHg) and high (red >30 mmHg) IOPs.