EYE TRACKER AS A TOOL SUPPORTING DIFFERENTIAL DIAGNOSIS IN THE STATES OF DISORDES OF CONSCIOUSNESS (DOC)

Abstract

One of the key parameters in the evaluation of disorders of consciousness (DOC) is visual behavior. In the past, visual potential testing or PET scanning was mainly used to assess these parameters. Recently, Eye Tracker (ET) technology for assessing visual functions has emerged; however, there are only a few publications devoted to the use of this technology in assessing people with disorders of consciousness (DOC). The purpose of this study was to evaluate the feasibility of using ET in the diagnosis of visual functioning in DOC patients.The study group consisted 25 patients (8 women and 17 men) awakened from prolonged post-traumatic coma in the Care and Treatment Facility of the "Light" Foundation in Toruń. The coma occurred as a result of severe brain damage: brain injury, stroke or sudden cardiac arrest. The mean age was 39.83 (SD 11.88) for the entire group, 38.85 (SD 9.99) for women, and 40.23 (SD 12.84) for men. All of these patients were in various states of disorders of consciousness (DOC), which was examined using the Coma Recovery Scale-Revised (CRS-R) (Giaciano et al., 2004). Appropriate inclusion and exclusion criteria were applied based on examinations by an internal medical physician and an ophthalmologist. Important exclusion criteria from the study were infection, elevated temperature, visual impairment and patient agitation. The visual functioning of the patients was measured with the use of the Eye Tracker Tobii X-120 device.A significant difference in visual functioning was demonstrated primarily in the areas of (1) reaction time to first fixation, where the Minimal Consciousness State minus (MCS-) group showed a significantly longer reaction time compared to the Minimal Consciousness State plus (MCS+) and the Emergency of Minimal Consciousness State (EMCS) groups; (2) fixation duration, where the MCS- group showed a longer time compared to patients in the MCS+ and EMCS groups; (3) the number of fixation points on the screen, where the MCS- group showed a significantly lower number of fixation points compared to the MCS+ and EMCS groups.Eye Tracker Tobii X-120 can serve as a valuable tool to aid in the neuropsychological diagnosis of individuals experiencing states of reduced consciousness. Indicators that most differentiate between the different levels of impaired consciousness include the time to the first fixation, the number of fixation points on the screen and the total number of fixations.