A Modified Schirmer Tear Test in Clinically Normal Horses: Measurement at 30 Seconds versus 60 Seconds.

The study explored the comparability of results from a 30-second and 60-second Schirmer Tear Test (STT) in healthy horses, ultimately finding the 30-second test to be a valid and efficient alternative to the 1-minute standard STT for diagnosing tear production.

Research Methodology

• The subjects of this study were 56 healthy horses, with tests performed on both eyes, beginning with the right.
• The Schirmer Tear Test (STT) is a standard diagnostic tool commonly used to detect dry eyes.
• Measurements of wetted area by tear production were taken at both 30-seconds (STT30) and 60-seconds (STT60).
• The velocity of wetting length was recorded for the initial 30-second period which helps in assessing the reduction of the initial reflex phase.
• Impact of various factors such as the eye (left or right), age, weight, sex, and ambient conditions like temperature and humidity on STT values were analyzed.

Results and Findings

• The average STT30 and STT60 results were found to be 19.06mm and 24.26mm respectively.
• A direct correlation was identified between the STT30 and STT60 scores. The linear relationship was expressed by the equation: STT60 = 2.20 + 1.18 × STT30 (with a confidence level p = .001).
• The variability of STT30 or STT60 results were observed to be independent of the sex of the horse, its age, weight, and ambient temperature and humidity conditions.

Conclusion

• The conclusion of the research was that the 30-second Schirmer Tear Test can efficiently diagnose tear production as accurately and reliably as the standard 60-second test.
• The shorter STT30 test can be a suitable alternative to the standard STT60, rendering it to be a more time-efficient diagnostic tool in clinical veterinary practice.