Equis ISSN 2398-2977

Eyeball: microphthalmos

Synonym(s): Button eye

Contributor(s): Keith Barnett, Dennis E Brooks, Graham Munroe

Introduction

  • Quite common, unilateral/bilateral congenital abnormal smallness of eye.
  • Cause: unknown etiology leading to congenital anomaly/dysplasia of embryologic eye.
  • Signs:
    • Size of globe varies depending on stage of gestation when embryo is affected.
    • Severe cases present with enophthalmos, blindness and passive prolapse of nictitans.
    • Poor nasolacrimal drainage, ocular discharge and conjunctivitis are common secondary problems.
    • May also be associated with cataracts and retinal dysplasia.
    • Most microphthalmic eyes are non-visual.
  • Treatment: none except enucleation   Eyeball: enucleation - transconjunctival  .

Pathogenesis

Etiology

  • Unknown.
  • Possible causes: toxic, mechanical, infectious or nutritional insults.
  • Hereditary in some species.

Pathophysiology

  • Congenital anomaly/dysplasia of partially formed optic vesicle in embryo.
  • Severity of microphthalmia depends upon gestational stage when insult occurs.

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.
  • Schutte J G et al (1997) Micophthalmia, brachygnathia superior, and palatocheiloschisis in a foal associated with griseofulvin administration to the mare during early pregnancy. Vet Q 19 (2), 58-60 PubMed.
  • Williams D L et al (1993) Bilateral optic disk colobomas and microphthalmos in a Thoroughbred horse. Vet Rec 132 (5), 101-103 PubMed.
  • Latimer C A et al (1985) Neonatal ophthalmology. Vet Clin N A Equine Pract (1), 235-259 (Review) PubMed.
  • Crowe M W et al (1985) Equine congenital defects. Am J Vet Res 46 (2), 353-358 PubMed.
  • Munroe G A et al (1984) Congenital ocular disease in the foal. Vet Clin N A Large Anim Pract (3), 519-537 (Review) PubMed.
  • Priester W A (1972) Congenital ocular defects in cattle, horses, cats, and dogs. JAVMA 160 (11), 1504-1511 PubMed.
  • Garner A et al (1969) Bilateral congenital ocular defects in a foal. Br J Ophthal 53 (8), 513-517 PubMed.

Other sources of information

  • Brooks D E (1999) Equine Ophthalmology. In: Veterinary Ophthalmology. Ed: Gelatt K N. 3rd edn. 1053-1116.


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