What to Do (and Not Do) when Treating Ulcers

Corneal ulceration is the erosion of normal tissue with a loss of corneal epithelium. Ulcers can be classified by size, depth and condition of the tissue, and can range from simple superficial abrasions to corneal ruptures with keratomalacia.

Corneal ulcers are most commonly due to accidental trauma by an exogenous factor (e.g. fencing, foreign body, straw) but can have an endogenous pathogenesis (e.g. entropion). It is therefore essential that the approach to any corneal ulcer is systematic, and this should involve careful evaluation of the periocular and ocular structures.

Cytology and culture should be considered if there is cellular infiltrate, and antimicrobial selection should be influenced by the results. The rate of re-epithelialisation of the equine cornea is 0.6 mm/day, and a simple corneal ulcer should heal within 5–7 days. Opportunistic microbial contamination of the corneal tissue can lead to significant complications, especially if there is stromal liquification or contamination of the intraocular environment.

The treatment strategy for a corneal ulcer should be based upon accurate identification of the ulcer type. It may be categorised as: simple superficial corneal ulceration; nonhealing spontaneous chronic corneal epithelial defect (SCCED); stromal ulceration; deep stromal ulceration; septic keratitis; keratomalacia; descemetocele; corneal laceration; corneal rupture; and iris prolapse.

Surgical intervention should be considered if the ulcer threatens the integrity of the globe, and may include: corneal crosslinking; keratectomy; direct corneal suturing; corneal autograft, allograft and xenograft techniques. Equine corneal surgery may be performed under standing sedation with suitable magnification, microsurgical instrumentation and cadaver training. Early referral to an ophthalmologist should always be considered if the ulcer is likely to require complex management.