Deep and Progressive Corneal Ulcers in Horses: Inhibiting Proteinase Activity, Cointrolling Uveitis, and Evaluating Response to Therapy

摘要

Corneal "melting" (i.e., keratomalacia) represents an imbalance between proteinase and proteinase-inhibitor activity within a diseased cornea. Increased activity of matrix metalloproteinases (MMPs) and serine proteinases has been identified in the tear fluid of horses with progressive corneal ulcers. Although microbial pathogens are implicated in the development of equine keratomalacia, this process does not rely solely on the presence of bacterial or fungal organisms. Proteinases may be liberated byleukocytes, corneal epithelial cells, and keratocytes within the tear film and cornea as part of the host response to injury. Because endogenous proteinase activity within the injured cornea may contribute to progressive stromal dissolution, debriding necrotic tissue and debris is an important step in ulcer management. Cautious debridement using cotton-tipped swabs and dilute (1:20) povidone--iodine solution following topical anesthesia may also be beneficial in rapidly reducing the microbial population of the external eye.