Comparison of 3 corneal cytology collection methods for evaluating equine ulcerative keratitis: Cytobrush, kimura platinum spatula, and handle edge of scalpel blade.

This research was conducted to compare three different methods of collecting corneal cytology samples in diagnosing ulcerative keratitis in horses. The study found the scalpel blade technique to provide the most diagnostic samples, although all methods proved beneficial in the clinical evaluation.

Methods

• The researchers included equine patients presented at the University of Florida College of Veterinary Medicine diagnosed with ulcerative keratitis.
• After diagnosing the corneal ulcer and collecting a microbial culture, each technique under scrutiny – the cytobrush, Kimura platinum spatula, and handle edge of a scalpel blade – was used to collect two cytology samples, picked at random.
• Cytological evaluation was performed by two observers, who were not aware of the particular collection technique used.
• Objective measures including sample cellularity, quality, distribution, and identification of infectious organisms were recorded for ten monolayer cell populations, viewed under 50x magnification with oil immersion.
• The researchers compared these findings to the results from the microbial cultures.
• They used statistical tests, including ANOVA and Student’s t-test, to compare the variables, as well as Cohen’s kappa to evaluate the agreement between observers and techniques.

Results

• Twenty horses, totaling 120 samples, were included in the study.
• The inter-observer agreement between the two observers was substantial, based on calculated k-values.
• The scalpel blade method provided the most cellular samples, which proved to be highly significant.
• There was a slight agreement in sample quality by different techniques.
• It was found that the samples from the cytobrush and scalpel blade methods had lower cell distribution than those from the Kimura spatula technique.
• The scalpel blade and cytobrush techniques had a significantly higher diagnostic yield in confirming infection than the Kimura spatula method.

Conclusions

• Overall, the study concluded that the scalpel blade method yielded the most diagnostic samples, hence making it the preferred choice for corneal cytology sample collection when diagnosing ulcerative keratitis in horses.
• However, it is worth noting that all three techniques were found to be clinically useful in diagnosing the condition, implying that they could be complementary in their application depending on the clinical setting and the resources available.