The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Pupillary diameter and light reflex.

The pupillary diameter and the pupilloconstrictor light reflex are the two parameters that have been studied extensively in relation to prognosis. Accurate measurement of pupil diameter or the constrictor response or the duration of the response has not been performed in studies on traumatic brain-injured individuals--for lack of a standardized measuring procedure. The following is recommended: 1. Pupillary light reflex for each eye should be used as a prognostic parameter. 2. The duration of pupillary dilation and fixation should be documented. 3. A pupillary size of >4 mm is recommended as the measure for a dilated pupil. 4. A fixed pupil should be defined as no constrictor response to bright light. 5. Right or left distinction should be made when the pupils are asymmetric. 6. Hypotension and hypoxia should be corrected before assessing pupils for prognosis. 7. Direct orbital trauma should be excluded. 8. Pupils should be reassessed after surgical evacuation of intracranial hematomas.