Ulcerative keratitis

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• 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.
• Diagnosis: relatively straightforward; use of fluorescein 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.

• Same as keratitis .
• Ocular discharge.
• History of trauma.

• If full investigation of viral etiology and subsequent treatment is undertaken.
• Deep ulcers that require microsurgical intervention can be expensive.

• Small corneal erosions (superficial ulcers), can heal quickly with few expenses needed.

• Trauma.
• Blunt, penetrating or perforating.
• Collagenases.
• Bacteria.
• Viruses - FHV-1 ulceration common.
• Corneal necrosis.

• Brachycephalic breeds.

• Keratoconjunctivitis (KCS) .
• Trauma.
• Feline herpes virus .

• Rapid progression of superficial ulcers to corneal rupture (melting ulcers), may occur as a result of bacterial activity.
• Indolent ulcers are non-healing epithelial erosions which do not penetrate the corneal stroma.

• Same as keratitis .
• Initial corneal injury allows bacteria to adhere to ocular surface.
• Bacteria, polymorphs or corneal keratocytes release proteases liquefaction of corneal stroma and rapid progression of some ulcers. (Most severe cases are termed 'melting ulcers'.)
• If stroma overlying Descemet's membrane is removed descemetocele (the exposed membrane then bulges forwards as a result of intra-ocular pressure).
   Descemetoceles do not stain with fluorescein.
• FHV-1 keratitis is epithelial unless topical steroid causes immunosuppression leading to stromal keratitis.

• Melting ulcers can progress over a matter of hours.

• Ocular pain.
• Red eye .
• Ocular discharge .
• Cloudy eye .

• Ocular discharge.
• Cloudy eye.

• Nictitans protusion.

• Trauma.

• Same as keratitis .
• Indolent ulcers have an epithelial lip.
• Deep ulcers appear as a crater-like defect.

• Conjunctivitis.

• Direct visualization of ulceration.

• Always take swabs for culture before applying topical anesthesia/vital stains.
• Linear, dendritic ulcers are suggestive of Feline herpes virus, especially in rapid progressive ulcers.

Cytopathology

• Corneoconjunctival scrapings may be useful.
• Corneal opacity makes intra-ocular examination difficult to impossible. Ultrasound may give valuable information.

Virology

• Viral isolation or PCR (polymerase chain reaction) (where available) for FHV-1 DNA.

Other

• Fluorescein staining - stain binds to denuded corneal stroma .
   Assess tear production (Schirmer tear test ) before adding fluid to eye.

Bacteriology

• History.
• Clinical signs.
• Ophthalmic examination.

• Fluorescein staining.

• Epithelial calls undergo mitosis and migration to heal a superficial ulcer.
• Stromal ulcers heal by fibrovascular infiltration.
• Deep ulcers tend to scar.

• Keratoconjunctivitis.
• Same as keratitis .

• Remove causative agent.
• Topical antibiotics are used to treat all corneal ulcers.
   Do not use topical corticosteroids.

• Atropine and systemic non-steroidal anti-inflammatories to prevent concurrent reflex uveitis.
• Agents to prevent corneal melting, eg acetylcysteine or EDTA , autogenous serum.
• Prevent self-trauma by physical restraints, eg Elizabethan collar .

• Topical nonsteroidal drugs (eye therapeutics) may reduce pain.

• Viral infection giving dendritic ulceration, confirmed by viral isolation or PCR (where available). treatment with anti-viral medication.
• Anti-virals are used to treat cats with herpes keratitis.
• Treat infection in cases of bacterial involvement based on results of bacteriology .
• Improve blood supply to affected region and support cornea using a conjunctival pedicle for deeper ulcers.
• Direct corneal suturing in cases of small deep ulcers (rarely indicated/feasible).
• Replacement of prolapsed iris tissue and corneal suturing if feasible - otherwise application of a pedicle flap if corneal rupture has occurred (as for corneal and scleral lacerations/perforations).

• Anticollagenases (acetylcysteine, EDTA), autogenous serum to prevent corneal 'melting'.

• Third eyelid flaps have a limited role in the treatment of deep ulcers.
   Third eyelid flaps are not advised in the treatment of rapidly progressing ulcers or those that are greater in depth than one-half of the corneal thickness.

• Topical atropine can reduce tear production.
• Increase in uveitis signs is associated with poor corneal healing.

• Refractory ulcers may require surgical removal of non-adherent epithelium prior to performing a grid or punctate keratotomy. Application of a membrane flap or a contact lens may be used in conjunction with this treatment regime.
• Superficial keratectomy to improve corneal transparency can be carried out 8-9 months after corneal repair to remove areas where there is considerable scarring.
   Topical corticosteroids should only be used once epithelialization has occurred - check using fluorescein.

• Same as keratitis .
• May leave a corneal defect (facet).

• Same as keratitis .
• Rapid healing of superficial ulcers.
• Corneal clarity and vision.
• Absence of pain.

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

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

• Dr Dennis E Brooks DVM PhD DipACVO
• Mr Peter Renwick MA VetMB DVOphthal MRCVS
• Dr David Williams MA VetMB PhD CertVOphthal FRCVS

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