Canis ISSN: 2398-2942

Persistent pupillary membrane

Synonym(s): PPM, mesodermal dysgenesis of anterior segment.

Contributor(s): David L Williams

Introduction

  • Typically arise from the anterior surface of the iris in the region of the collarette and insert in a variety of locations including the anterior lens capsule and corneal endothelium.
  • Cause: congenital failure of normal atrophy of embryonic vasculature of developing lens (tunica vasculosa lentis).
  • Inherited in Basenji.
  • Signs: usually no clinical problems may be associated with corneal opacities or cataract. Non-progressive.
  • Diagnosis: distinguish from post-inflammatory synechiae.
  • Treatment: usually none required.
  • Prognosis: usually excellent.

    At the severe end of the spectrum of anterior segment dysgenesis is Peters' Anomaly where the cornea and the lens fail to separate but this very rare in the dog and persistent pupillary membrane at the mild end of the spectrum is much more commonly seen.

Pathogenesis

Etiology

  • Congenital.
  • Inherited (in Basenji).

Pathophysiology

  • Often found in conjunction with multiple congenital ocular abnormalities.
  • Failure of normal atrophy of embryonic vasculature of anterior chamber → strands of iris tissue usually arising from anterior face of iris (at iris collarette) may → insert on iris, cornea or anterior lens capsule → focal capsular and subcapsular cataracts Persistent pupillary membrane Labrador 6 months.

Timecourse

  • May be identified at any age - usually non-progressive.

Diagnosis

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Treatment

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Outcomes

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Further Reading

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