Comparison of first, second, and third versus the average of six probe-corneal touches for intraocular measurement of two rebound tonometers in healthy horses.
Authors: Okur S, Yanmaz L E, Çınar H, Gölgeli A, Orhun Ö T, Turgut F, Şenocak M G, Arslan T
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Determining the most efficient method for measuring intraocular pressure (IOP) in horses has practical implications for clinical practice, particularly when time constraints make obtaining multiple readings difficult. Researchers compared single probe-corneal touches (first, second, and third) against the reference standard of six averaged measurements using two rebound tonometers (Tonovet and Tonovet Plus) on 38 stallions (24 Arabian and 14 crossbreds, mean age 8 years). The first touch showed superior agreement with the six-measurement average across both devices, with 89.5–97.4% of readings within 4 mmHg using the standard Tonovet, compared to only 65.8–78.9% with the Tonovet Plus; mean differences were negligible (0.1 mmHg for the Tonovet, 0.3 mmHg for the Tonovet Plus). For practitioners facing time pressures or uncooperative patients, a single initial measurement using the Tonovet represents a reasonable clinical compromise, though it should be noted that the Tonovet Plus demonstrated greater variability and may require the full six-reading protocol to achieve reliable measurements. These findings offer guidance on streamlining IOP assessment in equine practice without substantially sacrificing diagnostic accuracy.
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Practical Takeaways
- •When time is limited, a single first probe-corneal touch using Tonovet tonometer provides acceptable IOP measurement agreement with the standard six-touch average, making rapid screening feasible in field conditions
- •Tonovet appears more reliable than Tonovet Plus for abbreviated measurement protocols; consider instrument selection based on practice efficiency needs
- •IOP screening in healthy horses can be streamlined to single measurements without substantial loss of accuracy, improving practicality in busy equine practices
Key Findings
- •First probe-corneal touch (PCT) achieved best agreement with average of six PCTs using Tonovet tonometer (mean difference 0.1 mmHg, 89.5% within 4 mmHg)
- •Tonovet performed better than Tonovet Plus for single-touch measurements, with TV+ showing wider limits of agreement (-6.6 to 7.2 mmHg for first PCT)
- •Third PCT showed strongest agreement with six-touch average across both tonometers (97.4% within 4 mmHg for TV, 65.8% for TV+)
- •Single first PCT measurement can serve as practical alternative to six-touch protocol for IOP measurement in horses when time constraints exist