Equine Eye Vets Veterinary Eye Care for Horses
A corneal stromal abscess is a bacterial (frequently) or fungal infection within the collagenous stroma of the cornea. The corneal stroma makes up the bulk of the corneal thickness and is sandwiched between the outer (surface) epithelium and the inner (lining the anterior chamber) endothelium.
When the cornea is injured micro-organisms can be innoculated into he stroma. If the surface epithelium heals over the injury the organisms are trapped in the cornea where they can elicit an inflammatory response from the horse's immune system. white blood cells gain access to the corneal stroma and release enzymes;ynmes which break down the stromal tissue between the epithelial and endothelial layers forming an abscess. these abscesses may also develop in horses with systemic diseases although the mechanisms are poorly understood.
Stromal abscesses appear as painful white or yellow areas within the cornea - they often do not stain with fluorescein unlike corneal ulcers. Blood vessels will grow into the cornea, although this happens slowly. Associated inflammation with the eye (iritis, uveitis) develops as the corneal disease worsens and contributes to the pain associated with stromal abscesses.
The diagnosis is largely based on the history of a corneal injury and the appearance of the lesion.
Although medical therapy is often tried initially to treat this disease - many if not most progress despite therapy and ultimately need surgery in order to have any hope of resolving the disease favorably. Excision of the lesion in the stroma enables tissue to be obtained for culture and histopathology. Conjunctival grafts of grafts of adjacent corneal tisssue (or for deep abscesses donor corneal tissue) are used to speed the healing process.