title: The accuracy of eyelid movement parameters for drowsiness detection.
abstract: OBJECTIVE
  Drowsiness is a major risk factor for motor vehicle and occupational accidents. Real-time objective indicators of drowsiness could potentially identify drowsy individuals with the goal of intervening before an accident occurs. Several ocular measures are promising objective indicators of drowsiness; however, there is a lack of studies evaluating their accuracy for detecting behavioral impairment due to drowsiness in real time.
  
  
  METHODS
  In this study, eye movement parameters were measured during vigilance tasks following restricted sleep and in a rested state (n = 33 participants) at three testing points (n = 71 data points) to compare ocular measures to a gold standard measure of drowsiness (OSLER). The utility of these parameters for detecting drowsiness-related errors was evaluated using receiver operating characteristic curves (ROC) (adjusted by clustering for participant) and identification of optimal cutoff levels for identifying frequent drowsiness-related errors (4 missed signals in a minute using OSLER). Their accuracy was tested for detecting increasing frequencies of behavioral lapses on a different task (psychomotor vigilance task [PVT]).
  
  
  RESULTS
  Ocular variables which measured the average duration of eyelid closure (inter-event duration [IED]) and the ratio of the amplitude to velocity of eyelid closure were reliable indicators of frequent errors (area under the curve for ROC of 0.73 to 0.83, p < 0.05). IED produced a sensitivity and specificity of 71% and 88% for detecting ≥ 3 lapses (PVT) in a minute and 100% and 86% for ≥ 5 lapses. A composite measure of several eye movement characteristics (Johns Drowsiness Scale) provided sensitivities of 77% and 100% for detecting 3 and ≥ 5 lapses in a minute, with specificities of 85% and 83%, respectively.
  
  
  CONCLUSIONS
  Ocular measures, particularly those measuring the average duration of episodes of eye closure are promising real-time indicators of drowsiness.
authors: Institute for Breathing & Sleep, Department of Respiratory & Sleep Medicine, Austin Health, Victoria, Australia.
authors: Vanessa E
authors: VE
authors: Wilkinson
authors: Melinda L
authors: ML
authors: Jackson
authors: Justine
authors: J
authors: Westlake
authors: Bronwyn
authors: B
authors: Stevens
authors: Maree
authors: M
authors: Barnes
authors: Philip
authors: P
authors: Swann
authors: Shantha M W
authors: SM
authors: Rajaratnam
authors: Mark E
authors: ME
authors: Howard
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001767:Blinking / Q000502:physiology*; D005143:Eyelids / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology*; D012372:ROC Curve; D011930:Reaction Time / Q000502:physiology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012892:Sleep Deprivation / Q000503:physiopathology; D012894:Sleep Stages / Q000502:physiology*; D055815:Young Adult
keywords: Behavioral lapses; drowsiness; eye blinks; fatigue; ocular measures