When a horse has an “angry” eye, many times the horse has a defect involving the surface of the eye, known as a corneal ulcer. Other times, however, a painful eye could reveal a deeper problem—a corneal stromal abscess—a condition that equine ophthalmologists don’t want veterinarians to forget about.

Dennis Brooks, DVM, PhD, Dipl. ACVO, described these deep stromal abscesses (DSAs) during his presentation at the 2017 American Association of Equine Practitioners Convention, held Nov. 17-21 in San Antonio, Texas.

To briefly review: The cornea—the outer “window” that admits light to the eye—consists of several layers. On the outer surface, eight to 12 layers of epithelial tissue make up 15% of the total corneal thickness. Underneath lies a thicker layer called the stroma, followed by Descemet’s membrane, which is a single layer of endothelium (thin skin cells, essentially) that covers the cornea’s inner surface.

“Abscesses of the stroma are usually not ulcerated,” said Brooks, founder of the equine ophthalmology consulting firm BrooksEyes LLC. “Instead, horses typically present with painful uveitis or inflammation of the uvea. The uvea provides nutrition to various parts of the eye and, if inflamed, can cause painful blindness