canis - Articles
Pigmentary keratitis
Synonym(s): Pigmentary keratopathy, corneal melanosis
Introduction
- Cause: chronic keratitis → melanin deposition in cornea.
- Signs: superficial corneal vascularization and pigmentation.
- Common in brachycephalic breeds.
- Diagnosis: history, clinical signs, breed, ophthalmic examination.
- Treatment: remove cause, corneal lubricants, keratectomy if severe.
- Prognosis: guarded - may only be able to control signs.
- See also keratitis Keratitis.
Presenting signs
- Dark brown or black coloration of cornea.
Breed/Species predisposition
- Brachycephalic breeds.
Pathogenesis
Etiology
- Appear to be a combination of factors that cause chronic corneal irritation:
- Prominent globes and macropalpebral fissure → lagophthalmos (inadequate spreading of precorneal tear film over central cornea) → corneal dry spots formation.
- Corneal contact with nasal skin folds or excessive amounts of hair located at the medial canthus → corneal friction.
- Tear film abnormalities (keratoconjunctivitis sicca Eye: keratoconjunctivitis sicca).
- Chronic immunogenic stimulation (chronic superficial keratitis Chronic superficial keratitis/pannus).
Predisposing factors
General
- Any chronic corneal irritation can lead to corneal melanosis.
- Brachycephalic conformation: prominent globes in conjunction with macropalpebral fissure → tear film abnormalities (poor distribution of the tear film) → corneal dry spots.
- Keratoconjunctivitis sicca (KCS) Keratoconjunctivitis sicca.
- Nasal skin folds + length of facial hair, often in combination with entropion at the medial aspect of the lower eyelid: direct corneal contact at the nasal canthus. Trichiasis Trichiasis.
- Pannus Chronic superficial keratitis (chronic superficial keratitis).
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Kim S, Thomasy S M, Ramsey D et al (2018) Whorl pattern keratopathies in veterinary and human patients. Vet Ophthalmol 21 (6), 661-7 PubMed.
- Azoulay T (2014) Adjunctive cryotherapy for pigmentary keratitis in dogs: a study of 16 corneas. Vet Ophthalmol 17 (4), 241-249 PubMed.
- Labelle A L, Dresser C B, Hamor R et al (2013) Characteristics of, prevalence of, and risk fctors for corneal pigmentation (pigmentary keratopathy) in Pugs. JAVMA 243 (5), 667-674 PubMed.
- Bernays M E, Flemming D & Peiffer R L (1999) Primary corneal papilloma and squamous cell carcinoma associated with pigmentory keratitis in 4 dogs. JAVMA 214 (2), 215-217 PubMed.
- Shieh E, Boldy K L, Garbus J & McDonnell P J (1992) Excimer laser keratectomy in treatment of canine corneal opacities. Progress in Vet Comp Ophthal 2 (2), 75-79 VetMedResource.