Breed-Specific Relationship Between Rebound Tonometers (TonoVet and TonoVet Plus) in Labrador Retrievers.

TonoVet Plus reads approximately 4.5 mmHg higher than TonoVet in Labrador retrievers; account for this when switching devices.

This prospective observational study evaluated the relationship between two commonly used rebound tonometers—the TonoVet and TonoVet Plus—in 53 clinically normal Labrador retrievers (106 eyes) undergoing routine health screening in Japan. Both devices were used in dog mode, with measurement order effects assessed separately and found to be non-significant. Statistical analysis revealed that the TonoVet Plus consistently measured intraocular pressure (IOP) approximately 4.5 mmHg higher than the TonoVet, with a statistically significant systematic bias (p < 0.0001) and moderate inter-device correlation (r = 0.69). Bland-Altman analysis confirmed this systematic bias with 95% limits of agreement ranging from 1.3 to 7.7 mmHg, indicating clinically meaningful variability at the individual level. Deming regression, which accounts for measurement error in both instruments, yielded a slope of 1.05 and an intercept of 3.52, providing a breed-specific approximation formula: TonoVet Plus IOP ≈ 1.05 × TonoVet IOP + 3.52. Age-related IOP effects were small and non-significant. The authors emphasize that this approximation is most appropriately applied at the population or longitudinal monitoring level rather than for precise individual predictions. The study is limited by its single-breed, single-country design and the use of only the first of three readings per device. External validation in independent Labrador retriever cohorts is recommended before broad clinical application. These findings are particularly relevant for veterinary practices or guide dog programs transitioning between tonometer models.

This summary was distilled by AI and may occasionally misinterpret data. Confirm critical details with the primary literature before clinical application.