Preliminary observations on tear film interferometry performed in horses.
Authors: Cattaneo A, Guandalini A, Peruccio C
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Tear Film Interferometry in Equine Ophthalmology Cattaneo, Guandalini and Peruccio have conducted the first equine tear film interferometry study, using non-invasive optical analysis to characterise normal tear dynamics and correlate tear film changes with keratitis presentation in horses examined across Northern Italy between 2019 and 2021. Their retrospective analysis of 64 horses—18 clinically normal controls and 46 with various forms of keratitis—established preliminary reference intervals for non-invasive break-up time (NIBUT: 10.4–31.2 seconds) and tear meniscus height (TMH: 0.215–0.457 mm) using the Ocular Surface Analyser in veterinary mode. A particularly noteworthy finding was the consistent presence of punctate ocular surface lesions detectable by interferometry in all cases of active fungal keratitis, distinguishing this presentation from non-infectious inflammatory keratitis, where such lesions were absent. Whilst the study's limitations—modest sample size and presumptive diagnosis in some infectious cases—warrant cautious interpretation, these observations offer equine practitioners a novel diagnostic tool for differentiating keratitis aetiology and establishing baseline tear film parameters, potentially improving clinical decision-making in cases of equine corneal disease where distinguishing infectious from immune-mediated pathology remains diagnostically challenging.
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Practical Takeaways
- •Tear film interferometry using the Ocular Surface Analyser may help differentiate infectious (fungal) from non-infectious keratitis in horses, potentially aiding clinical decision-making before culture/treatment results
- •Establish baseline tear film values for your practice population to improve diagnostic accuracy, as these preliminary reference intervals provide initial benchmarks for comparison
- •Consider tear film assessment as part of complete ophthalmic examination in horses with keratitis, particularly when differentiating keratomycosis from immune-mediated disease
Key Findings
- •Preliminary reference interval for non-invasive break-up time (NIBUT) in healthy horses is 10.4-31.2 seconds
- •Preliminary reference interval for tear meniscus height (TMH) in healthy horses is 0.215-0.457 mm
- •Punctate ocular surface lesions on tear film interferometry were present in all cases of active diagnosed or presumptive keratomycosis but absent in all non-infectious keratitis cases
- •This is the first reported use of tear film interferometry as a diagnostic technique in horses