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
