Histopathological features of equine superficial, nonhealing, corneal ulcers.

This research study explores the changes in the cornea related to chronic, non-healing superficial corneal ulcers in horses, and attempts to identify consistent histopathological features. The findings suggest that while the characteristics of epithelial nonadherence, epithelial dysmaturity, and mild to moderate stromal inflammation are frequently observed in these cases, there isn’t a definitive set of characteristics that could be used to define this condition in horses.

Research Objectives and Methods

• The study aimed to evaluate the changes in horse corneas associated with chronic, non-healing, superficial corneal ulcers using common histopathological stains.
• This was a retrospective study involving the medical records of 24 horses that were diagnosed with chronic, non-healing, superficial corneal ulceration between 2005 and 2011 at North Carolina State University’s Veterinary Teaching Hospital.
• The horses included in the study underwent superficial keratectomy (SK), had superficial corneal ulceration, and showed no cellular infiltration or microorganisms evident on corneal cytology.
• The corneal tissue samples collected were evaluated for the presence or absence of various features such as a non-adherent epithelial ‘lip’, epithelial dysmaturity, intraepithelial inflammatory cells, an acellular hyaline zone in the anterior stroma, and stromal inflammatory cells, fibrosis and vascularization.

Results of the Study

• The investigation revealed that in most samples, the epithelial cells near the ulcerated site were not adhering to the basement membrane and were dysmature.
• Intraepithelial inflammatory cell infiltration was rarely seen in the samples.
• Features such as an anterior stromal hyaline zone, intrastromal inflammation, fibrosis and vascularization were found to be variably present in the samples.
• Despite the variability, the most consistent characteristics were epithelial nonadherence, epithelial dysmaturity and mild to moderate stromal inflammation.

Conclusions from the Study

• The study concluded that while epithelial nonadherence, epithelial dysmaturity and mild to moderate stromal inflammation are commonly found in equine chronic, non-healing, superficial, corneal ulcers, the syndrome doesn’t have a definitive set of histopathological characteristics.
• Another observation was that an anterior stromal acellular hyaline zone, which is commonly mentioned in relation to canine spontaneous chronic corneal epithelial defects (SCCED), was not consistently seen in equine corneas.