Reverse King-Devick Test and History of Multiple Concussions
Condition: Concussion, Mild
MeSH terms: Brain Concussion
Study type: Interventional

Summary: 
      The purpose of this study is to examine the effects of concussion history and reading
      direction on baseline King- Devick Test (KDT) performance, a common component of sideline
      concussion assessments. The KDT is a timed assessment of saccades, or quick movements of the
      eyes between two points. This test is a form of rapid automatized naming and involved
      subjects reading digits arranged on a tablet screen as quickly and accurately as possible.
      The test has three progressively more challenging test "cards," as the horizontal guidelines
      between digits disappear from test card 1 to 2, and the vertical spacing between the lines of
      digits decreases from test card 2 to 3. KDT performance is evaluated in terms of both speed
      (duration to all three test cards) and the number of errors (digits read incorrectly or
      omitted). Previous studies have identified several factors that affect KDT performance aside
      from head injury, including age, sex, sleep deprivation, learning disabilities, and first
      languages other than English. History of concussion has not been shown to influence KDT
      performance. The investigators hypothesize that since the left-to-right (L-R) reading
      direction of the KDT is the same way in which to read English, the long-term effects of prior
      concussions on saccadic eye movements may be masked. The investigators want to answer the
      following three research questions: 1) What is the effect of KDT reading direction on
      baseline KDT performance? If the test is performed by reading digits in a right-to-left (R-L)
      direction, will KDT times be slower and the number of errors increase relative to a typical
      L-R KDT? 2) What is the effect of a history of multiple concussions on KDT performance
      relative to no history of concussion? 3) Is the R-L KDT more sensitive to a history of
      multiple concussions? The investigators hypothesize that individuals with a history of
      multiple concussions will perform significantly worse (longer test durations, more errors)
      than individuals with no concussion history on the R-L KDT. On the other hand, the
      investigators hypothesize that baseline performance on the traditional L-R KDT will not be
      able to discriminate individuals with a history of multiple concussions from those with no
      concussion history.
    

Detailed description: 
      Subjects will first be asked to complete a questionnaire. This questionnaire will collect
      demographic data (age, sex, years of education, native language and other languages spoken)
      and other pertinent data (vision correction, concussion history, ocular/visual injury and
      disorder history, learning disability diagnoses). The questionnaire will take approximately 3
      minutes to complete.

      Based on the concussion history provided in the questionnaire, the subject will be assigned
      to either Group NoHx (no concussion history) or Group HxMC (history of multiple concussions.)
      Then the subject will be randomized into one of two KDT formats: L-R KDT (natural reading
      direction) or R-L KDT (reverse reading direction) via a coin flip. The researcher will
      explain the KDT procedure by saying, "This test evaluates your saccadic eye movements, or
      rapid eye movements from one fixation point to the next. This test is comprised of three test
      cards. Each test card has eight lines of several digits (numbers). Please read the digits
      aloud as quickly but as accurately as possible from [L-R condition: 'left to right and top to
      bottom'; R-L condition: 'right to left and top to bottom']. If participants make a mistake,
      correct it if participants can and continue on. This is a timed test--tapping the tablet
      screen starts and stops the stopwatch. Participants will have a brief break in between cards
      to catch participants' breath. Each test card will get progressively harder. The horizontal
      lines guiding participants from digit to digit on each line on Test Card 1 disappear on Test
      Card 2. The lines of digits on Test Card 3 are closer together than they were on Test Card 2.
      Do you have any questions?"

      The researcher will start the app and pull up the demonstration card for the L-R condition.
      For the R-L condition, the researcher will open a picture of the adapted demonstration card
      with the diagonal lines switched to indicate that subjects follow from the left-most digit to
      the right-most digit on the subsequent line. Subjects will complete the demonstration card
      twice according their condition instructions. Subjects will be reminded to "read the digits
      as quickly but accurately as possible" and in the direction according to their assigned test
      condition before starting the test. The researcher will silently count any errors while the
      subject completes each test card one at a time, taking a brief (1-2s) pause after tapping the
      screen to stop the timer and tapping again to start the timer and bringing up the next test
      card. At the conclusion of the test, the researcher will record the total time and number of
      errors on the subject data collection sheet. The subject will complete the test a second
      time, following the same instructions. The total time and number of errors for the second
      attempt will also be recorded. The investigators anticipate this portion of the data
      collection to take approximately 6 minutes. The total duration of the data collection will be
      approximately 10 minutes.
    

Intervention name(s): Conventional King-Devick test; Reverse King-Devick test
Intervention type(s): Diagnostic Test; Diagnostic Test
Intervention description(s): Conventional King-Devick test involves a series of number reading task from left to right and top to bottom, intending to test subjects' neuro-ophthalmologic function; Reverse King-Devick test involves a series of number reading task from right to left and bottom to top, intending to test subjects' neuro-ophthalmologic function
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Outcomes Assessor)
Primary purpose: Diagnostic