Validation of the Effectiveness of the SafetyScopeTM Ocular System
in Quantifying Sleepiness

Phase I: Proof-of-Concept Pilot Study

Executive Summary by Circadian Technologies, Inc.

Introduction:
Previous studies have demonstrated that ocular measures have the potential to indicate drug- and fatigue-related impairments. While SafetyScopeTM (Eye Dynamics, Inc.) has been used as an ocular device for drug testing, it has not yet been evaluated and applied to the detection of impaired alertness levels.

The current project aimed to scientifically evaluate and validate the effectiveness of SafetyScopeTM in detecting impaired alertness levels by comparing the device output (passed/failed/invalid) with multiple Alertness Testbed measures in a sleep deprivation protocol. Phase I of this project, conducted to test the overall concept and to help design a subsequent full-scale validation study, was completed in May 2001. The results of this initial laboratory pilot study are summarized below.

Methods:
SafetyScopeTM was evaluated in an overnight sleep deprivation protocol using Circadian Technologies' multiparametric Alertness Testbed. Testbed measurements included: assessment of subjective sleepiness (Visual Analog Sleepiness Scale and Thayer Activation-Deactivation Adjective Checklist), performance measurements during a 30-min driving simulation task and during a 10-min performance vigilance task (PVT), quantification of behavioral signs of sleepiness (video recordings during driving task), and detection of microsleep events (continuous recording of electro-physiological parameters).

SafetyScopeTM used a 90-sec test to record pupil diameter and eye movement parameters. The data of each test was compared with each subject's individual baseline (established prior to the experiment based on three consecutive SafetyScopeTM tests), and then classified into one of the following three categories: passed, failed, invalid.

The measures of the Alertness Testbed and SafetyScopeTM were collected in 1-hour test sessions, starting every 2 hours from 1400 to 0600 hours.

A total of six healthy subjects (four male, two female; aged 22-33 years) participated in one overnight experiment each as well as in a pre-experiment screening and practice session.

Results and Conclusions:
Overall, the expected circadian alertness pattern, most consistently shown in subjective alertness measures, was reflected by the trends of the SafetyScopeTM results. SafetyScopeTM indicated "failed" and "invalid" test results particularly at nighttime when the Alertness Testbed measures showed the highest sleepiness levels. All of the non-passed SafetyScopeTM tests occurred either at night or during the mid-afternoon alertness dip.

In this small pilot study, inter-individual variations in the ability to stay alert and perform were seen. Interestingly, the least sleepy subject, who was not very impaired by sleep deprivation according to the Alertness Testbed measures, passed all SafetyScopeTM tests. Those subjects determined to have the most sleepiness impairment by the Alertness Testbed were detected by SafetyScopeTM non-passed results.

Comparing the results for equal time windows before and after midnight, the percentage of non-passed tests (relative to the total number of tests) increased from 0% to 25% for the 1600-2230 and 2400-0630 time windows, respectively (not including data for the least sleepy subject).

In conclusion, SafetyScopeTM seems potentially to be a promising device for detecting impaired alertness levels. Based on the trends emerging from this pilot study and because of the need to establish and validate alertness test devices for a variety of practical applications (e.g., fitness-for-duty devices), it is recommended that this initial pilot study be expanded into a full validation study with a larger subject group. The test protocols for this full-scale study will be designed in a way that allows for the measurement of a wide alertness range with particular focus on extreme sleepiness levels. Based on the data of the full-scale study, it will be possible to validate and tailor SafetyScopeTM for the measurement of impaired alertness.