Rehabilitation For Acquired Visual Field Defects: Development Of A Bottom-Up Approach

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.


Eligibility Criteria:
Inclusion Criteria:

* Male/Female
* Stroke (ischemia or hemorrhage) documented by CTscan or MRI
* Traumatic brain injury (TBI) documented by CTscan or MRI
* Right or Left hemianopia defined by perimetry
* All subjects must be between the ages of 18-80
* Aetiology of visual field defect : Stroke (ischemia or hemorrhage)
* Delay post-stroke : at least 6 months
* Only one lesion on CTscan or MRI (performed in a maximal delay of 6 months)
* Corrected monocular visual acuity \> 5/10
* Possible understanding of experimental conditions
* Patient being able to be quiet and sit during at least 2 hours
* Having given written informed consent prior to any procedure related to the study
* Availability for the period of the study
* Covered by a Health System where applicable, and/or in compliance with the recommendations of the national laws in force relating to biomedical research

Exclusion Criteria:

* Ophthalmologic criteria : monocular visual acuity \< 4/10, strabismus , diplopia , ocular instability , nystagmus, maculopathy , glaucoma , retinopathy , orthoptic rehabilitation
* Neurologic criteria : sever phasic disturbances , neurologic degenerative affection , non controlled seizure , severe handicap non compatible with prolonged sit position or concentration during 30 consecutive minutes
* No command of french language
* Non stabilized medical situation
* Females who are pregnant, nursing, or planning a pregnancy during the study period, or females of childbearing potential, not using a reliable means of contraception.
* Not under any administrative or legal supervision