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Method and device for detection and assessment of marijuana impairment

  • US 10,646,115 B2
  • Filed: 09/05/2019
  • Issued: 05/12/2020
  • Est. Priority Date: 10/20/2015
  • Status: Active Grant
First Claim
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1. A method of identifying individuals impaired by a psychoactive substance other than alcohol, the method comprising:

  • presenting monocularly to a subject being tested;

    to each eye separately, a pattern of fixed spatial frequency with achromatic contrast between dark areas and light areas, the achromatic contrast between the dark areas and the light areas being temporally alternately modulated at a temporal frequency that ranges between 10 Hz and 60 Hz with a pattern of the contrast being such that the subject being tested can see a frequency doubling in the pattern thereby evaluating retinal function;

    decreasing the contrast of the pattern presented until a first contrast ratio/value is reached wherein the frequency doubling in the pattern is no longer reported as being seen by the test subject;

    further decreasing the contrast of the pattern until a second contrast ratio/value is below the test subject'"'"'s threshold of detection of the second contrast ratio/value;

    increasing the contrast of the pattern until a third contrast ratio/value is reached where the frequency doubling in the pattern is first detectable;

    comparing the first contrast ratio/value and the third contrast ratio/value to a range of expected values of a normal population who have not consumed the psychoactive substance and have no pathology impacting retinal visual functions tested;

    if the first contrast ratio/value and the third contrast ratio/value are within the range of expected values, then indicating that the test subject is not impaired; and

    if the first contrast ratio/value and the third contrast ratio/value are not within the range of expected values then indicating that the test subject is impaired.

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