ISSN 2398-2977      

Vitreous: opacities

pequis

Introduction

  • The equine vitreous consists of a clear, semi-fluid gel which is relatively acellular and has an organised structure of 99% water with 1% collagen and hyaluronic acid.
  • This definitive gel structure is retained throughout the horse's life with little or no liquefaction but progressive dilution of the gel matrix is part of normal adult development.
  • True liquefaction (syneresis) is rare other than accompanying posterior segment inflammatory disease   Vitreous: vitritis (vitreous haze)  .
  • A range of inclusions or opacities are detected in the vitreous including remnants of the hyaloid apparatus   Hyaloid apparatus disease  , changes associated with vitritis   Vitreous: vitritis (vitreous haze)  , intravitreal hemorrhage , and vitreoretinal detachment .
  • Other vitreal opacities are considered remnants of embryonic tissues or condensations of normal adult structures   →   minimal effect on vision.
  • Many of these inclusions appear to float freely in the vitreous, moving in response to eye or head movement, particularly in the more liquid vitreous of Cloquet's canal.

Vitreal floaters

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Vitreal degeneration

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Chandler K J, Billson F M & Mellor D J (2003) Ophthalmic lesions in 83 geriatric horses and ponies. Vet Rec 153 (11), 319-322 PubMed.

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