Symptom2 connections · 1 source

Third Eyelid Prolapse

Elevation or protrusion of the nictitating membrane across the inner corner of the eye.

Key Facts

It occurs when sympathetic tone to the smooth muscle of the third eyelid is lost.
The membrane appears more prominent and covers part of the cornea.
It is a consistent clinical feature of Horner's syndrome in companion animals.
It results from unopposed parasympathetic contraction of the retractor bulbi muscle.

It is a classic clinical sign used to identify the syndrome.

Its elevation is driven by unopposed parasympathetic nerve activity.