Persistent Pupillary Membrane

Synonyms

Hyperplastic persistent pupillary membrane. (Some authors consider these to be different than persistent pupillary membranes. See Clinical Relevance below.)

Definition

The presentation of incomplete involution of the in utero pupillary membrane with or without accompanying blood vessels from the underlying tunica vasculosa lentis.

Structure

In utero, the neural crest-derived iris stroma extends across the fetal pupil with strands arising from the iris collarette. There may be communications with the underlying tunica vasculosa lentis, a network of vessels formed by the anterior extension of the hyaloid artery, on the anterior lens surface especially in the peripheral regions. In the third trimester, these strands that cross the pupil resorb. Regression is aided by macrophage phagocytosis, the dysfunction of which may predispose to pupillary membranes. If there is failure of resorption, a pupillary membrane (Fig. 1) may be seen postnatally.

Persistent Pupillary Membrane, Fig. 1