Often, abnormally dilated pupils are also fixed pupils. – 3.35 mm in direct light – 3.86 mm in normal room lighting – 6.41 mm in near-total darkness It is a prelude to, or indicative of really, “brain death”. This is usually due to swelling of the brain, and herniation of the brain stem. Well, traditionally in Medicine, “dilated and fixed pupils” are associated with severe brain damage. What does it mean when pupils are dilated and fixed? For many years it has been recognized that when a patient with evidence of increased intracranial pressure becomes suddenly comatose and shows one dilated and fixed pupil, a presumptive localization of an expanding lesion in the ipsilateral cerebral hemisphere is permissible. What happens to pupils with increased intracranial pressure?įrom the Montreal Neurological Institute.

Can fixed dilated pupils be reversed?Ĭonclusions and implications of key findings Despite the poor overall prognosis of patients with closed head injury and bilateral fixed and dilated pupils, our findings suggest that a good recovery is possible if an aggressive surgical approach is taken in selected cases, particularly those with extradural haematoma. One or both of your pupils can become fixed in the dilated position and can’t react to light. Pressure that builds inside your brain after a head injury, stroke, or tumor can damage the muscles in your iris that normally make your pupils open and close. Dilated pupils aren’t the same as anisocoria, a common condition where both pupils react normally to light but differ in size by about a half-millimeter or more. What does it mean when a person’s eyes are fixed?Ī large pupil that is completely unresponsive to light is called a “fixed” dilated pupil.

Unequal pupil size causes