Felis ISSN 2398-2950

Cornea: ulcerative keratitis

Contributor(s): Dennis E Brooks, Peter Renwick, David Williams, Natasha Mitchell

Introduction

  • Important ocular disease characterized by loss of corneal epithelium plus variable amounts of stroma.
  • Cause: complex; trauma, collagenase activity and bacterial/viral infections should be considered.
  • Mycotic infection is more common in dogs than cats in the USA.
  • Signs: ocular discharge, red eye, corneal ulceration, painful eye.
  • Diagnosis: relatively straightforward; use of fluorescein dye and ultraviolet/cobalt blue light is strongly advised.
  • Treatment: remove causative agent(s) and create an environment suitable for healing.
  • Prognosis: corneal rupture is a possibility in cases of deep ulceration. Recurrence is likely if the underlying cause is not identified and treated.

Pathogenesis

Etiology

  • Trauma: blunt, penetrating or perforating.
  • Collagenases.
  • Bacteria.
  • Viruses - FHV-1 ulceration common.
  • Adnexal abnormalities, eg exposure keratitis, entropion, eyelid mass rubbing, eyelid agenesis Eyelid: abnormality.
  • Corneal necrosis (corneal sequestrum) Cornea: sequestration.

Predisposing factors

General

  • Brachycephalic breeds. Lagophthalmos, poor distribution of the tear film, entropion at the medial aspect of the lower eyelids, and globe exposure making trauma more likely are all factors involved.

Specific

Pathophysiology

  • Rapid progression of superficial ulcers to corneal rupture, may occur as a result of collagenase activity. Liquefactive corneal necrosis, or corneal 'melting' is a very serious potential complication of all forms of corneal ulceration.
  • Indolent ulcers are non-healing epithelial erosions which do not penetrate the corneal stroma. FHV-1 may be the cause.
  • Same as keratitis Keratitis.
  • Initial corneal injury  →  allows bacteria to adhere to ocular surface.
  • Melting ulcers occur following liberation of collagenase enzymes from invading microorganisms, white blood cells or keratocytes, which cause rapidly collagenolysis and loss of corneal structure.
  • If stroma overlying Descemet's membrane is absent  →  descemetocele (the exposed membrane then may bulge forwards as a result of intra-ocular pressure).
    Descemetoceles do not stain with fluorescein dye at the base, but the edges of the ulcer are fluorescein positive.
  • FHV-1 keratitis is epithelial unless topical steroid causes immunosuppression leading to stromal keratitis.
  • Corneal sequestrum occurs as a result of stromal collagen necrosis.

Timecourse

  • Melting ulcers can progress over a matter of hours.
  • Superficial ulcers can be chronic and present for several weeks.
  • Ulcers that become corneal sequestra can be present for many months to years.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • La Croix N C, van der Woerdt A & Olivero D K (2001) Nonhealing corneal ulcers in cats - 29 cases (1991-1999)​. JAVMA 218 (5), 733-735 PubMed.
  • Featherstone H & Sansom J (2000) Intestinal submucosa repair in two cases of feline ulcerative keratitis. Vet Rec 146 (5), 136-138 PubMed.
  • Kern T J (1990) Ulcerative keratitis. Vet Clin North Am Small Anim Pract 20 (3), 643-666 PubMed.

Other sources of information

  • Petersen-Jones S & Crispin S (2002) BSAVA Manual of Small Animal Ophthalmology. 2nd edn. British Small Animal Veterinary Association. ISBN 0 905214 54 4


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