Patients who have suffered neurological brain damage that has resulted in a visual field deficit have additional difficulties with eye movements. They appear to have smaller saccade amplitudes, exploring more of the sighted regions rather than the blind areas, have a larger number of fixations and a lower ability to integrate information between the left and right hand side of their vision. Therefore, they have difficulties in becoming aware of the events at the side of their visual field loss and in grasping a scene as a whole.
The way a person selects items in their visual fields as targets for consecutive eye movements is based on a combination of those items’ visible features (such as brightness, colour and movement) and the person’s attention and intentions.
When a part of sight is affected, the process of target selection is impaired and the pattern of eye movements becomes abnormal leading to difficulties interacting with the environment. Spontaneous recovery is the exception not the rule and only about 20% develop effective compensatory behaviour. Visual search tasks have proved successful in re-training a patient to make more efficient eye movements.
Following training, patients have larger saccade amplitudes and the integration of visual information from the left and right-hand side of their vision improves.
The improvements are specific to the type of training a patient undergoes: for example specific training to improve reading ability after brain injury is not effective for visual search. It is now well established that improvements in eye movement training have a beneficial effect on a patient’s activities of daily living, leading to better quality of life and are independent of a patient’s age.
These improvements translate to a significant and positive impact in a patient’s interaction with their environment.