A system and method are provided for detecting and monitoring Pupillary Light Reflex responses and physical conditions using a portable video capture device (PVCD) for the purpose of diagnosing or monitoring impairment due to consumption of intoxicating substance or neurological disorder due to trauma or illness. In one embodiment, the PVCD is placed in an opaque enclosure, and positioned over one or both eyes. Video of the eyes is captured over a predetermined time using a video camera of the PVCD, and the video processed to measure changes in a feature of at least one eye. Data from the measured changes is analyzed together with additional physical data collected on a condition of the user, to estimate a degree of impairment. The degree of impairment and additional physical data is output to the user through a user interface in the PVCD and stored in local and remote memory for monitoring.
