Biofeedback Training to Improve Fixation Stability, Visual Function Outcomes, and Quality of Life in Hemianopia Cases

Background

Patients with brain injury secondary to stroke, surgery, or trauma frequently suffer from homonymous hemianopia, defined as vision loss in one hemifield secondary to retro- chiasmal lesion. About 45% of stroke survivors have homonymous hemianopia. A deficit in vision and spatial perception can cause slowdown of the rehabilitation progress in physiotherapy.

According to Kerkhoff 1patients face three main visual behavioral problems: (1) impaired eye movements (including saccades) leading to defective visual and spatial exploration, (2) hemianopic reading deficit (hemianopic alexia) because of the parafoveal field loss and (3) deviated subjective midline. Hemianopic dyslexia is not simply the product of the visual field defect but is caused by a disorder of control of visual information processing and eye movements in reading.

Most important, the capability to read is fundamental for daily living and an essential prerequisite for education and success in our modern society, so this disorder can have a profound effect on patients' lives. Patients with visual field loss usually fail to adapt to their reading impairment (80% of cases). In these cases, word identification and the abilities to plan and guide reading eye movements are disturbed.

In spite of these facts, visual rehabilitation program on a larger scale is still missing in most rehabilitation centers and clinics. This is decurrent to the generalized belief that lesions of the lateral geniculate nucleus and striate cortex lead to a permanent loss of vision. According to scientific findings, this does not always have to be true.