Equis ISSN 2398-2977

Lens: subluxation/luxation

Contributor(s): Dennis E Brooks, Graham Munroe

Introduction

  • Incidence: rare; congenital or acquired; often associated with other ophthalmic problems, eg microphthalmia   Eyeball: microphthalmos  , multiple ocular defects   Eye: defect - overview  , ocular trauma , cataracts   Cataract: overview  , glaucoma and chronic uveitis   Uveitis: anterior - overview  .
  • Signs: luxation may occur anteriorly or posteriorly   →   changes in the anterior chamber, iris movement and lens position.
  • Treatment: surgical removal - only required where there is increasing intra-ocular pressure, ocular pain or an unstable lens.
  • Prognosis: guarded.

Pathogenesis

Etiology


EitherCongenital - non-heritable.
OrAcquired.

Pathophysiology

  • A rare condition.
  • Congenital or acquired.
  • Congenital examples are usually associated with other congenital abnormalities such as glaucoma or cataracts, are bilateral and non-inherited.
  • The primary defect is the abnormal type and number of lens zonules.
  • Acquired causes are more common, including:
  • Luxation occurs when the lens is displaced completely from the patellar fossa where it normally sits on the front of the vitreous and just behind the iris.
  • The subluxated or luxated lens is either cataractous or will become cataractous.
  • The vitreous may liquefy in response to the lens movement.
  • The lens can move to several locations or become attached by inflammatory exudates:
    • The lens may move through the pupil and into the anterior chamber   →   damage to corneal endothelium   →   corneal edema +/- anterior uveitis and glaucoma (possibly).
    • If pupil occluded   →   impeded aqueous flow dynamics.
    • May sink backwards into the liquefied vitreous and adhere to the inferior retina.

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.
  • McCluskie L K, Woodford N S & Carter W J (2009) Posterior lens luxation with associated glaucoma in a pony. Equine Vet Educ 21 (5), 228-231 VetMedResource.
  • Gelatt K N (1973) Glaucoma and lens luxation in a foal. Vet Med Small Anim Clin 68 (3), 261 PubMed.

Other sources of information

  • Brooks D E (1999) Equine Ophthalmology. In: Veterinary Ophthalmology. Ed: Gelatt K N. 3rd edn.


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