Visual field improvement in neglect after virtual reality intervention: a case study

Abstract

Objective. Studies on neuropsychological rehabilitation of visual field defects provide an inconsistent picture regarding the effectiveness of so-called "restorative approaches" in visual field recovery (VFR). During a current research project on the clinical evaluation of VFR - in combination with head mounted virtual reality displays (HMD) - a patient ("Patient 7") suffering from visual neglect was investigated. Although the concept of VFR is originally not intended for patients suffering from higher cortical regions (as in neglect), we hypothesized that due to the strong attention-demanding training situation in HMDs, neglect patients might benefit from these intervention procedures based on restorative approaches. Methods and Analysis. Patient 7 was examined perimetrically using a "Humphrey Field Analyzer", "Goldmann Perimetry" and our newly developed and validated eye-tracking supported perimetric methodology "Eye tracking based visual field analysis" (EFA). Based on these high resolution results from the EFA, the exact location of the transition area between intact and defect visual field of Patient 7 was assessed. Next, bright light stimuli were placed along this area in our newly developed HMD "Salzburg Visual Field Trainer" (SVFT). The aim was to stimulate neuroplasticity - according to the concept of restitutive approaches - in the corresponding cortical areas of the patient. Patient 7 trained with the SVFT for a time period of 254 days. In 6 appointments the objective and subjective rehabilitation progress was assessed. Results. Perimetric assessment with the EFA shows an expansion of Patient 7's visual field of 48.8% (left eye) and 36.8% (right eye) after 254 days of training with the SVFT. Individual areas in the patient's visual field show a visual improvement of approximately 5.5 to 10.5 degree of visual angle. Subjective self-report of Patient 7 additionally shows improvements in self-evaluation of up to 317% in visual field functionality compared to self-evaluation on the first assessment date. Conclusions. The results from Patient 7 indicate that patients suffering from visual neglect potentially benefit from a neuropsychological intervention with HMD based on the restorative concept of visual field recovery. However, further studies with large case numbers and a focus both on daily-life improvements and on a clear distinction between patients with lesions in earlier and higher cortical areas are needed to make empirically valid and generalizing statements about our findings.