Felis ISSN 2398-2950

Eye: persistent pupillary membrane

Synonym(s): PPM; anterior segment dysgenesis

Contributor(s): Natasha Mitchell, David Gould

Introduction

  • Cause: a form of anterior segment dysgenesis which occurs due to incomplete regression of the embryonal pupillary membrane.
  • Signs: thin strands of iris tissue arising from the iris collarette.
  • Diagnosis: from visual inspection.
  • Treatment: no treatment is usually required.
  • Prognosis: good, the majority do not change throughout life once present in the young adult.

Pathogenesis

Etiology

  • Congenital ocular developmental defect.
  • Sporadic occurrence - it does not appear to be inherited.

Predisposing factors

General

  • It may arise in combination with other ocular defects such as microphthalmia and eyelid coloboma Eyelid: abnormality.

Pathophysiology

  • The pupillary membrane and anterior tunica vasculosa lentis provide nutrition to the developing lens and anterior chamber in the fetus.
  • Regression is underway at birth, and should be complete by six weeks of age.
  • Failure of complete regression results in varying amounts of tissue being left permanently present.
  • Persistent pupillary membranes appear as strands and always arise from the iris collarette, which is the junction between the ciliary zone and pupillary zone on the iris surface.
  • Single or multiple strands may span the iris (iris to iris), attach to the anterior lens capsule (iris to lens) or span forwards to attach to the corneal endothelium (iris to cornea).
  • Iris to iris strands are generally clinically insignificant.
  • Iris to lens strands can result in focal cataract, and occasionally vision-impairing cataract Cataract.
  • Iris to cornea strands can cause focal corneal opacity (leukoma) Eye: corneal opacity and occasionally corneal edema or thinning.

Timecourse

  • Present at birth and remains throughout life if still present by six weeks of age.

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.
  • Glaze M B (2005) Congenital and hereditary ocular abnormalities in cats. Clin Tech Small Anim Pract 20 (2), 74-82 PubMed.

Other sources of information

  •  Natasha Mitchell & James Oliver (2015) Feline Ophthalmology - The Manual. Grupo Asis. ISBN 978-84-16315-11-6.


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