Brain lesions - acquired or traumatic - can lead to visual field problems that are easily missed in early rehabilitation yet these respond best to early intervention. So what can be done? In this article we look at a few tools in RehaCom to help with the management of visual field deficits.
Approximately 50% of stroke survivors with visual field disturbances suffer from visual field loss. The nature and location of the brain lesion dictates the specific symptoms experienced and the type of visual field loss. (See figure)
Sight loss could be over a small area (scotoma) or cover the entire visual field in one hemifield (hemianopia). Although some recovery of vision may take place in the acute phase without active intervention the probability of substantial recovery diminishes with time with little recovery might be expected after six months. The onset of visual impairment has a devastating effect on stroke survivors who frequently report that questions regarding their eyesight were not asked in the initial stages of treatment.
There are three classes of rehabilitation technique that can potentially be used to help sight loss after stroke. These are substitution, adaptation or restitution approaches.
RehaCom has both Screening and Training modules that impact upon visual field issues.
RehaCom Screening modules that are relevant include
- Visual Field
- Visual Scanning
RehaCom Training modules include
- Restoration Training
- Saccadic Training
RehaCom's Visual Field Screening (VITE) Screening
This screening is used to measure the nature and extent of the visual field and fixation accuracy of a user. In neurological hospitals, rehabilitation clinics or outpatient neuropsychological practices perimeters are often not available. By use of VITE the therapist has a sufficiently accurate instrument, to indicate and map visual field deficits, neglect symptoms and reading disorders. As result of the test a visual field map can be printed.
RehaCom's Visual Scanning (ZIHT) Screening
The Visual Scanning Screening allows measuring the performance of a patient to explore his visual field. Two parameters are measured: parallel search and serial search. Parallel search is the ability to explore the visual field “at a glance”. Serial search is the ability to explore the visual field “in a structured way”. The ability to explore the visual field quickly needs to be trained after hemianopia and other visual field defects.
RehaCom’s Visual Restoration training
This is a “restitution” approach to improve visual function in persons with visual impairments due to neurological lesions. An intense visual stimulation is provided in the area of the border zone between the intact and defective parts of the visual field.
The training is designed for patients with neurologically induced visual field deficits such as hemianopia or quadrantanopia. Different levels of difficulty and individually adjustable duration allows the use also for patients with attention and concentration disorders or deficits of motor and perceptual functions.
During the training task the user can use our optional Chin Rest. The user sits in a comfortable but fixed position in front of the monitor. Throughout the whole session he/she is required to look straight ahead at the monitor maintaining an optimum fixed distance. On the dark monitor a coloured fixation point is presented and has to be fixed during the entire session. The user needs to respond at every colour change of the fixation point. A bright stimulus moves from the intact visual field towards the blind area, and users have to confirm every flash of the stimulus. At the same time the client has to concentrate on the fixation control point.
With respect to the training material, a large white stimulus will be presented, starting in the intact visual fi eld and moving slowly towards the impaired area of the visual field. An interactive algorithm ensures intense light stimulation exactly in-between the border of the intact visual field to the blind area.
RehaCom’s Saccadic training module
This training is designed to increase the visual search are and partial compensate for the visual field impairment. Saccadic training is indicated for persons with visual field deficits and neglect after a stroke, traumatic brain injury, certain brain tumours and MS. The software is suitable for persons aged 8 years and up.
You can see a short video here on the Saccadic training module. Other RehaCom videos in the series are also available
During the training task the client can see a horizon on the screen with a very simple structured landscape. In the middle of the screen, a big sun is displayed. At irregular intervals, an object appears left or right of the sun. Whenever the client notices an object, he has to press the corresponding reaction button (left or right arrow key of the RehaCom Panel).
The training material is very comprehensive with 34 levels of difficulty and the system automatically increases or decreases the difficulty of material depending on the user’s response. On the screen, a horizontal line is visible. At easier levels, a sun is indicated in the middle for a better orientation of the client. In irregular time intervals, different objects or symbols, e.g. animals, cars, bikes, motorcycles etc., appear on the horizontal line. At higher levels of difficulty, the symbols become smaller, the horizon disappears, and additional attention-deflecting stimuli are shown and fade again. With Opti-kinetic stimulation the user looks at a series of moving strips which stimulate the vestibular-ocular reflex into the neglected side.
If you would like to know more about RehaCom training or screening modules there is lots of content on-site here. You can also request a demo disc.