Constriction Velocity

Constriction Velocity refers to the speed at which the iris constricts, making the pupil smaller, in order to reduce the amount of light entering the eye. This measurement is taken when the phone light is turned on at 2 seconds into the exam. On the Constriction Velocity Chart, the Constriction Velocity for each pupil is shown over time, giving a quick visual indication of whether there is notable difference between each pupil.

Max. Constriction Velocity refers to the maximum millimetres per second (mm/s) speed recorded for each pupil. Recordings are labelled as follows:

Avg. Constriction Velocity refers to the average millimetres per second (mm/s) speed recorded for each pupil measured from the time when the phone light is turned on (2 seconds into the exam) to the time of minimum pupil size. Recordings are labelled as follows:

Constriction Time refers to the total time in seconds recorded from the phone light turning on (2 seconds into the exam) to the time of minimum pupil size. Recordings are labelled as follows:

Constriction Distance refers to the recorded difference in millimetres (mm) between the starting pupil diameter and the minimum recorded pupil diameter. Recordings are labelled as follows:

Constriction Velocity results can indicate whether or not the brain is functioning normally. Increased Constriction Velocity beyond normal range can be an indicator of concussion. More information can be found in the below references.