Refinement and revalidation of the Equine Ophthalmic Pain Scale: R-EOPS a new scale for ocular pain assessment in horses.

This research article investigates the effectiveness of an improved version of the Equine Ophthalmic Pain Scale (EOPS) for accurately assessing pain in horses suffering from eye-related diseases. The researchers modified the original scale, focused on behavior and facial and ocular expressions, and tested it on horses with ocular diseases and healthy controls to determine its reliability and validity.

Refining and Revalidating the Equine Ophthalmic Pain Scale (EOPS)

• The research team revised the original EOPS by only including behavioral and facial and ocular expression indicators to assess pain.
• The revised scale (R-EOPS) was tested on two groups. Group P consisted of 13 horses with ocular diseases while Group C consisted of 16 healthy horses used as controls.
• For each horse, the R-EOPS was applied at the start (T0) and one week later (T7). Researchers recorded two 30-second videos at each time point for retrospective analysis by eight observers.

Assessing the Reliability and Validity of the R-EOPS

• The inter-observer reliability (reliability between different observers) of items was moderate or substantial (Krippendorff’s alpha, Kα>0.40); whereas, intra-observer reliability (reliability within the same observer) was substantial or almost perfect for most items (Kα ≥0.61).
• The total score (TS) showed excellent inter- and intra-observer reliability (Intraclass Correlation Coefficients, ICC>0.75), good reproducibility (Kendall coefficient=0.786, ICC=0.684) and high consistency (Cronbach’s α=0.847).
• The researchers performed comparisons between groups and assessed sensitivity and specificity values to determine the validity of the R-EOPS.

Findings and Conclusions

• The study found that for each additional point in the TS, the risk of the horse experiencing pain more than doubled (Odds Ratio=2.079, 95% Confidence Interval=1.542-2.804; P<0.001).
• A Receiver Operating Characteristic analysis determined 6 as the threshold value of the R-EOPS for accurately distinguishing horses with an ocular disease (sensitivity=83%, specificity=100%).
• The results suggest that the R-EOPS can be an effective tool for reliably assessing pain in horses with eye-related diseases and potentially assisting in pain management. However, further large-scale application and external validation of the scale is needed.