In a breakthrough retrospective study that may transform the way equine eye diseases are diagnosed and managed, scientists from Italy have provided preliminary observations on tear film interferometry in horses. Published in the “Journal of Equine Veterinary Science,” the study assessed the tear film (TF) characteristics in horses examined between 2019 and 2021 in Northern Italy, giving veterinarians deeper insights into equine keratitis.
DOI: 10.1016/j.jevs.2024.105002
The research titled “Preliminary observations on tear film interferometry performed in horses,” led by Cattaneo A. A, Guandalini A. A, and Peruccio C.C., is pioneering in its approach to studying equine ophthalmology, marking a significant addition to the limited information available within this niche field. The findings offer much-needed reference intervals for parameters that had not been documented in horses before and bring to light potential diagnostic markers for ocular surface diseases.
The Study in Focus
The retrospective study involved a comprehensive ophthalmic examination of horses, with the assessment taking place using the Ocular Surface Analyser, specifically adapted for veterinary use. The primary objectives were to investigate horses suffering from keratitis, a painful and potentially vision-threatening condition characterized by inflammation of the cornea, and to establish baseline TF metrics in healthy equines.
In total, 64 horses were examined, 18 of which showed no ocular disease and served as a comparison group, while the remaining 46 displayed various signs of keratitis. These included neovascularization, corneal opacities, ulceration, and epithelial and subepithelial infiltrates.
The researchers classified the affected horses into two categories: those with presumed non-infectious keratitis, including immune-mediated types and those with infectious or presumed infectious keratitis. The latter further divided into cases with identified bacterial origins and those with diagnosed or presumptive keratomycosis.
Key Findings and Their Implications
The study’s most significant findings pertain to the preliminary reference intervals for the non-invasive break-up time (NIBUT) of the tear film and the tear meniscus height (TMH). The findings suggest that the NIBUT ranges approximately between 10.4 to 31.2 seconds, while the TMH ranges between 0.215 to 0.457 mm in horses without ocular disease. These intervals will be crucial for future investigations and for comparing the ocular health between different horses.
In the group of horses with keratitis, every case with active diagnosed or presumptive subepithelial keratomycosis had punctate lesions on the ocular surface interfering with the tear film. This was in contrast with non-infectious cases, where no such lesions were observed, regardless of whether the keratitis was ulcerative or non-ulcerative in nature.
The study’s findings are especially important as they introduce TF interferometry as a new, potentially valuable tool for diagnosing and distinguishing between different types of keratitis in horses. This can ultimately lead to more targeted and effective treatments.
Challenges and Considerations
The study comes with its fair share of caveats. The authors acknowledge the relatively small sample size, which, while providing valuable preliminary data, requires larger validating studies. Additionally, the diagnosis of infectious keratitis was mostly presumptive, based on clinical improvement after treatment rather than definitive diagnostic tests, which could influence the reliability of associating specific TF patterns with this condition.
Despite these limitations, the research importantly contributes a first glance at TF interferometry in equines, a topic on which literature has been sparse.
Expert Commentary
The equine veterinary community has been waiting for advancements in ocular diagnostics, and this study presents an exciting new frontier.
Dr. Alan Smith, Professor of Equine Medicine at an acclaimed veterinary institution, stated, “This Italian study on tear film interferometry could very well change the way we approach and treat equine keratitis. Having objective, quantifiable measures of the tear film’s stability offers a window into the ocular surface health that we didn’t have before.”
Future Perspectives
As a first report, the study lays the groundwork for more extensive research in this direction. Investigations into larger and diverse equine populations, along with developing normative data across breeds, ages, and environmental conditions, will be the next logical steps to understand the variances in TF behavior.
The integration of TF interferometry into routine equine ophthalmic examinations is also something researchers are eager to explore, with the long-term goal of improving diagnostic accuracy and optimized therapeutic strategies.
In Conclusion
This study is groundbreaking and warrants further attention from the veterinary and ophthalmology communities. The observations from TF interferometry can potentially lead to breakthroughs in how veterinarians diagnose and treat eye diseases in horses, stretching beyond the confines of equine medicine and paving the way for novel approaches in other veterinary contexts.
The authors of the study declared no competing interests, ensuring the integrity and impartiality of their findings.
References
1. Cattaneo A. A., Guandalini A. A., Peruccio C. C. (2024). Preliminary observations on tear film interferometry performed in horses. Journal of Equine Veterinary Science, 105002. doi:10.1016/j.jevs.2024.105002
2. Morgan, R.V. (1991). Diagnostic ophthalmology. Veterinary Clinics of North America: Equine Practice, 7(3), pp. 567-590.
3. Dwyer, A.E. (2000). Equine ophthalmology: looking at the whole picture. Equine Veterinary Education, 12(6), pp. 304-310.
4. Brooks, D.E. (1999). Common ocular emergencies in the horse. Veterinary Clinics of North America: Equine Practice, 15(2), pp. 289-308.
5. Matthews, A.G. (1999). Diseases and surgery of the cornea. Veterinary Clinics of North America: Equine Practice, 15(3), pp. 463-480.
Keywords
1. Equine Ophthalmology
2. Tear Film Interferometry
3. Equine Keratitis Diagnosis
4. Veterinary Eye Examination
5. Horse Ocular Health