New Technology for Diagnosing Keratitis in the Equine Eye

A technology commonly used in human medicine would provide veterinarians with a quick, noninvasive alternative for diagnosing fungal keratitis in the equine eye, according to a researcher from Cornell University.

Equine fungal keratitis is a common painful corneal infection that can lead to blindness if not treated immediately and aggressively with antifungal and anti-inflammatory medications. Some affected horses require surgery to save their vision. What can complicate treatment in fungal keratitis cases is that early clinical signs (including squinting, ocular discharge, and redness to the tissues around the eye) are commonly overlooked, so the infection often goes unnoticed until the cornea becomes cloudy.

Currently, veterinarians diagnose fungal keratitis by taking a scraping from the surface of the horse's eye (a corneal biopsy) and sending the sample to a laboratory for evaluation (examination under a microscope and/or culture). The wait for the results can delay onset of valuable treatment for days to weeks, according to Eric C. Ledbetter, DVM, Dipl. ACVO, of Cornell University College of Veterinary Medicine in New York. He and his colleagues examined a noninvasive diagnostic alternative that is commonly used in human ophthalmology: use of a corneal confocal microscope, which provides a high-definition image of the various layers of a living eye.

In his study, Ledbetter and colleagues evaluated 12 horses with naturally acquired fungal keratitis, as well as experimentally infected corneas in the laboratory. Using confocal microscopy, the team was able to see structures indicative of infection--including leukocyte infiltrates, activated keratocytes, and anterior stromal dendritic cell infiltrates, among others--that would allow for a quick diagnosis of fungal keratitis. "The in vivo (in the living animal) corneal confocal microscope provides similar information to a standard corneal biopsy," Ledbetter said. "However, this technology is noninvasive and provides immediate results as opposed to standard biopsy techniques."

The equipment for this technique is not yet widely available for horses, he added.

The study, "In vivo confocal microscopy of equine fungal keratitis," was published in the January issue of Veterinary Ophthalmology. The abstract is available on PubMed.

About the Author

Marie Rosenthal, MS

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