Equine Immune-Mediated Keratitis Study Guide

Overview and Clinical Importance

Immune-mediated keratitis (IMMK) represents a group of non-infectious, non-ulcerative inflammatory disorders of the equine cornea. These conditions are characterized by chronic corneal opacity resulting from an aberrant immune response, likely triggered by foreign proteins, microbial antigens, or self-antigens. IMMK is common in both Europe and North America and represents a significant category of equine ophthalmologic disease on the NAVLE.

The hallmark of IMMK is chronic corneal opacity without corneal ulceration or significant uveitis. Classic histopathologic findings include lymphocytic-plasmacytic corneal cellular infiltrates, often accompanied by corneal neovascularization, edema, and fibrosis. Early diagnosis and appropriate immunomodulatory therapy are essential for preserving vision.

Pathogenesis and Etiology

The pathogenesis of IMMK remains incompletely understood, but an aberrant immune reaction to corneal antigens is considered highly likely given the favorable response to topical corticosteroids and cyclosporine A therapy.