Ultrasound evaluation of pupil: secrets of the "black hole" unveiled.

This Letter to the Editor is in response to Stevens and colleagues, who presented a study about pupillometry in patients with traumatic brain injury. They did not find any correlation between pupil diameter and intracranial pressure. We agree with the clinical importance of pupil assessment and we would like to suggest the application of transorbital ultrasound for this evaluation. This approach has been proposed in the past and, with our work, we show the possible quantification of symmetry of pupil diameter variation in response to a stimulus. This approach may represent a proficient and safe method for patients' supervision.