A Modified Schirmer Tear Test in Clinically Normal Horses: Measurement at 30 Seconds versus 60 Seconds.
Authors: Martín-Suárez Eva M, Mesa Pablo, Portillo Miguel, Morgaz Juan, Moreno Ofelia, Guisado Alicia, Galán-Rodríguez Alba
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Modified Schirmer Tear Test at 30 Seconds in Healthy Horses Tear film assessment remains clinically important for diagnosing keratoconjunctivitis sicca and other ocular conditions in horses, yet the standard 60-second Schirmer Tear Test (STT) is time-consuming in practice. Researchers measured tear production in 56 clinically normal horses at both 30 and 60 seconds, establishing reference ranges and statistical relationships whilst investigating potential influences of age, sex, weight, and environmental conditions. Mean tear wetting lengths were 19.06 mm at 30 seconds and 24.26 mm at 60 seconds, with a strong linear correlation between the two timepoints (STT60 = 2.20 + 1.18 × STT30), and notably, tear production values were unaffected by sex, age, weight, ambient temperature, or humidity. These findings suggest that the 30-second modification provides diagnostically equivalent information to the traditional 60-second protocol, making it a practical alternative for busy clinical environments. Practitioners can confidently adopt the abbreviated technique to streamline ophthalmic screening whilst maintaining diagnostic accuracy, though establishing age- and individual-specific reference ranges for clinical horses presenting with suspected tear deficiency would strengthen clinical application.
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Practical Takeaways
- •The 30-second Schirmer test can replace the standard 60-second test, saving 50% of clinical time while maintaining diagnostic accuracy for tear film assessment
- •Environmental factors and patient variables (age, weight, sex) do not significantly affect test results, simplifying clinical interpretation
- •This modified protocol is practical for field work and routine equine ophthalmologic screening without compromising diagnostic reliability
Key Findings
- •Mean STT30 was 19.06 mm and STT60 was 24.26 mm in healthy horses
- •Strong linear correlation exists between STT30 and STT60 (STT60 = 2.20 + 1.18 × STT30, P = 0.001)
- •STT values did not vary by sex, age, weight, ambient temperature, or humidity
- •STT30 provides accurate and reliable tear production assessment compared to standard STT60 measurement