Validation of Recalibrated IOPVet in Canine Eyes Compared to Manometry and Recalibrated TONOVET Plus

To evaluate the clinical and manometric accuracy of a recalibrated version of the IOPVet indentation tonometer in dogs, and to compare its performance to a recalibrated TonoVet Plus (rTVP) and in situ direct manometry.

A total of 97 eyes from 49 client-owned dogs were enrolled and divided into three groups: a glaucomatous group of 34 dogs (67 eyes: 41 glaucomatous, 26 fellow normotensive eyes), a control group of 10 healthy dogs (20 eyes), and a manometric group of 10 eyes from 5 euthanized dogs.

IOP was measured using both the rTVP and the recalibrated IOPVet, each device being used by a separate examiner. IOPVet readings were recorded as semi-quantitative intervals: < 10, 10-29, 30-49, and ≥ 50 mmHg. Agreement with rTVP and manometric values was assessed through sensitivity, specificity, and Chi-square analysis. Manometry was performed post-mortem using dual-needle in situ cannulation over a range of pressures (10-70 mmHg).

All glaucomatous eyes (rTVP ≥ 30 mmHg, n = 41) were correctly classified by the IOPVet (sensitivity 100%). Among normotensive eyes (rTVP ≤ 29 mmHg, n = 46), 78.3% were correctly categorized, with 21.7% overestimated (specificity 84.8%). The association between rTVP and IOPVet categories was significant (χ² = 50.2, df = 4, p < 0.0001). In manometric validation, accuracy was 95% (10-29 mmHg), 100% (30-49 mmHg), and 94% (≥ 50 mmHg), with no misclassification below 30 mmHg.

The recalibrated IOPVet demonstrates markedly improved accuracy, excellent sensitivity, and acceptable specificity in detecting elevated IOP in dogs. Its affordability and ease of use support its integration into clinical practice and owner-assisted glaucoma monitoring.