Response Latency

Response Latency is a measurement of the reaction time of the eye in response to when the phone light is turned on at 2 seconds into the exam. On the Pupil Diameter (latency period) Chart, the latency period is indicated by two vertical white lines, the first at 2 seconds into the exam and the second at the time at which the iris begins to constrict.

Response Latency refers to the time in seconds between the phone light turning on (2 seconds into the exam) and the beginning of measured iris contraction (measured against a baseline created at seconds 0-2 of the exam, which is before the phone light is turned on). Recordings are labelled as follows:

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