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Eye: lens luxation

ffelis

Introduction

  • Cause: lens luxation occurs when there is breakdown of the supporting lens zonules.
  • In cats, lens luxation usually occurs secondary to other intraocular disease, in particular uveitis.
  • Anterior lens luxation is associated with corneal damage and secondary glaucoma.
  • Diagnosis: gross ocular and ophthalmoscopic examination should reveal above signs.
  • Treatment: surgical lens extraction and treatment of other intraocular disease.
  • Emergency treatment is rarely required (in contrast to dog).
  • Prognosis: fair if treatment prompt and any other intraocular disease adequately controlled.

Pathogenesis

Etiology

  • Primary luxation:
    • Congenital:
      • May be associated with microphakia.
    • Hereditary
      • Inheritance as a dominant trait possibly as a result of mutation in the FBN1 gene has been reported.
  • Secondary luxation:

Predisposing factors

General

Pathophysiology

  • Lens luxation occurs when there is complete 360° breakdown of the lens zonules.
  • Subluxation occurs when there is incomplete breakdown of the lens zonules.
  • Breakdown of lens zonules may be a result of:
    • Congenital or inherited weakness.
    • Inflammatory damage.
    • Globe stretching (glaucoma).
    • External trauma.
    • Cataract (increased lens weight).
    • Damage from intraocular neoplasia.
  • The lens may luxate anteriorly into the anterior chamber or posteriorly into the vitreous.
  • Anterior lens luxation is most common and leads to further complications:
    • Corneal edema:
      • Owing to direct damage to corneal endothelium and compromise of pump mechanism responsible for keeping cornea relatively dehydrated and clear.
    • Secondary glaucoma:
      • Pupillary block from presence of lens and/or vitreous within pupil.
      • Compromise of aqueous outflow via iridocorneal angle.
  • Retinal detachment Retina: detachment is another common long-term complication following lens luxation.

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.
  • Maggs D J (2009) Feline uveitis. An 'intraocular lymphadenopathy'. J Feline Med Surg 11 (3), 167-182 PubMed.
  • Townsend W M (2008) Canine and feline uveitis. Vet Clin North Am Small Anim Pract 38 (2), 323-346 PubMed.
  • Payen G, Hänninen R L, Mazzucchelli S et al (2005) Primary lens instability in ten related cats: clinical and genetic considerations. JSAP 52 (8), 402-410 PubMed.
  • Sansom J (2000) Diseases involving the anterior chamber of the dog and cat. In Practice 22 (2), 58-70 VetMedResource.
  • Molleda J M, Martín E, Ginel P J et al (1995) Microphakia associated with lens luxation in the cat. JAAHA 31 (3), 209-212 PubMed.
  • Olivero D K, Riis R C, Dutton A G et al (1991) Feline lens displacement - a retrospective analysis of 345 cases. Prog Vet Comp Ophthalmol (4), 239-244 VetMedResource.

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