Rehabilitation For Acquired Visual Field Defects: Development Of A Bottom-Up Approach
Condition: Acquired Visual Field Defects
Study type: Interventional

Summary: 
      Cortical Visual Field Defects (CFVD) are common after acquired brain injury. They often cause
      problems with reading and visual exploration which impact on patients' quality of life. Apart
      from the substitutive method that uses prisms directly placed on glasses, two main
      rehabilitative methods have been explored previously: one restorative and one compensatory.
      The most effective methods seem to be based on compensatory training paradigms that target
      eye movements. They rely on voluntary mass-practice that induces changes in exploratory
      saccadic behaviour, particularly into the blind hemifield. Previous studies using this method
      have shown changes in visual scanning patterns but with only a marginal profit in terms of
      functional benefit.

      In the present study, the investigators developed a new approach to the compensatory visual
      field training based solely on a bottom-up mechanism. It does not require the patients'
      ability to voluntarily maintain attention oriented to the affected field, which may be
      difficult for brain-damaged patients. As previously reported in other pathological contexts
      (e.g. use of prism adaptation or sensory stimulation in neglect patients), bypassing
      voluntary and conscious implication of the patient can produce improvements by a more
      automatic process.

      The investigators hypotheses are: 1) that a novel ramp-step search paradigm can be used by
      hemianopic patients to automatically improve targeted eye movements into their blind visual
      field; and 2) that this will lead to behavioural improvements on ecologically valid tests of
      visual search.
    


Intervention name(s): Treatment A; Treatment B
Intervention type(s): Other; Other
Intervention description(s): The computer-based training task consists of a novel ramp-step search paradigm with a stimulus traversing the screen from left to right or right to left. Subjects are asked to pursue the stimulus (ramp phase) and then saccade to find its location when it suddenly jumps (step phase). The stimulus is an open spinning circle. At the end of each movement, the gap can be located at the top or at the bottom, and patients are asked to indicate this location by pushing the response button as quickly as possible.
The starting point will alternate between left and right. The training task includes 3 sessions with 100 movements each. Reaction Times and errors will be monitored online to ensure that the patient performs the task correctly.
Each treatment phase has the same pattern:
two visits in pre-tests evaluation (V1 and V2),
one visit to perform treatment (A or B) and to assess immediate and 2h post-effects (V3),
two visits after treatment (V4 at one week and V5 at one month).; Placebo treatment using the same computer-based training task, but including only the ramp phase.
Each treatment phase has the same pattern:
two visits in pre-tests evaluation (V1 and V2),
one visit to perform treatment (A or B) and to assess immediate and 2h post-effects (V3),
two visits after treatment (V4 at one week and V5 at one month).
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Other