---
title: What is pupillary membrane?
description: "A persistent pupillary membrane is a remnant of foetal tissue that once covered the pupil and normally regresses before birth. Fine strands may remain across or around the pupil but usually do not affect vision. ## Appearance and Effects The…"
url: "https://bluefinvision.com/knowledge-base/topics/conditions-diseases/what-is-pupillary-membrane/"
updated: "2025-12-11"
category: "Conditions & Diseases"
---

# What is pupillary membrane?

A persistent pupillary membrane is a remnant of foetal tissue that once covered the pupil and normally regresses before birth. Fine strands may remain across or around the pupil but usually do not affect vision.

## Appearance and Effects

The membrane typically appears as delicate, thread-like strands arising from the iris collarette and crossing the pupil or attaching to the lens capsule. Most are partial and allow adequate light entry without causing significant symptoms.

- Common incidental finding in otherwise normal eyes
- Strands may regress further with age
- Dense membranes can rarely blur vision or cause irregular pupils
- Distinguished from inflammatory synechiae by history and appearance

## Management

Most persistent pupillary membranes require no treatment and are simply observed. Intervention may be considered if a dense membrane obstructs the visual axis, particularly in young children at risk of amblyopia.

- Regular monitoring ensures normal visual development in paediatric cases
- Surgical or laser removal is rarely needed and reserved for significant obstruction
- Careful assessment rules out other causes of anterior segment strands
- Visual prognosis is generally good when the membrane is thin or partial