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MedicalDictionary.comThe Free Veterinary Medical Dictionary
Medical Condition🐕 Dogs🐈 Catsophthalmic

Corneal Ulceration

🗣️ Pronounced:KOR-nee-ul UL-ser
In One Sentence (Plain English)

A painful wound or break in the outer epithelial layers of the cornea on the surface of the eye.

Editorial Status: Verified from peer-reviewed veterinary sources (v1.0)
Updated: 2026-01-15

💬 In Plain English

The cornea is the clear, transparent outer dome of the eye. Because the cornea is densely packed with nerve endings, any scratch, scrape, or injury causes intense pain. When the surface epithelium is damaged, a corneal ulcer is created. Pets squint tightly (blepharospasm), tear profusely, paw at their face, and shy away from light. If bacteria invade, enzymes can start “melting” the deeper stromal layers of the cornea, risking eye rupture within 24 to 48 hours.

🔬 Clinical & Technical Depth

For Vets & Technicians

Formal Clinical Definition

Loss of corneal epithelium and exposure of the underlying stroma. Classified by depth into superficial, stromal, descemetocele (erosion down to Descemet’s membrane), and perforating ulcers.

Why Veterinarians Use It

Veterinarians diagnose corneal ulcers using fluorescein dye, which sticks to the water-soluble stroma beneath damaged epithelium and glows bright green under cobalt blue light.

Clinical Context Encountered

Encountered after minor trauma (scratching from plants or cats), foreign bodies, eyelashes rubbing the cornea (distichiasis), or secondary to dry eye (KCS) or feline herpesvirus.

Clinical Reference Guide (Medical Condition)

Severity
Emergency StatusNon-Emergency Care
🚨 Red Flag Warnings (When to Contact an Emergency Vet)
  • •NEVER apply eye drops containing steroids (such as dexamethasone or hydrocortisone) to a squinting eye: steroids stop corneal healing and can cause rapid eye perforation.
  • •A deep melting ulcer can perforate within 24 hours, leading to permanent blindness or eye loss.

❓ Questions to Ask Your Veterinarian

Take these actionable questions with you to your next clinic visit or appointment:

  • 1How deep is the ulcer (superficial vs. deep stromal)?
  • 2Did the fluorescein stain show any signs of a descemetocele (thin membrane bulge)?
  • 3Is there any evidence of “melting” cornea (enzymatic keratomalacia)?
  • 4Is my pet wearing a properly fitted Elizabethan collar (cone) to prevent pawing?

Academic & Clinical References