Canis ISSN: 2398-2942

Pigmentary keratitis

Synonym(s): Pigmentary keratopathy, corneal melanosis

Contributor(s): David L Williams, Natasha Mitchell

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.

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.
  • 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.

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.
  • 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.


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