Assessing Functional Vision in Cerebral Visual Impairment with Wearable Eye Tracking

Functional visual deficits are often present in individuals with cerebral visual impairment (CVI). We characterized gaze behavior while CVI participants performed the Star Cancelation Task (SCT) and Developmental Test of Visual Perception (DTVP) as assessments of visuospatial processing and visuomotor integration, respectively. Gaze behavior was recorded using the Tobii Pro Glasses 3 in five CVI subjects (mean age=21.20 years  4.66 SD) and eight controls (mean age=22.13 years  4.16 SD). For the SCT, both groups performed at ceiling (i.e. no targets missed). However, CVI subjects had higher fixation (81.05%) and saccade counts (67.31%), shorter average fixation durations (42.62%), and shorter average saccade amplitudes (18.68%) compared to controls. These findings suggest that while there was no evidence of visuospatial neglect, search behavior in CVI was comparatively different from that of controls. Regarding the DTVP, the CVI group showed evidence of impaired copying abilities and had overall higher fixation counts (23.18%) and shorter average fixation durations (40%) compared to controls. Both groups had higher fixation counts (CVI: 9.68%; Control: 31%) and longer average fixation durations (CVI: 20.51%; Control: 97.78%) while viewing the drawings compared to targets as well as a trend of increasing fixation counts with increasing target complexity. In general, we found that gaze behavior in CVI was characterized by a greater number of fixations and decreased fixation duration, as well as an increased number of saccades and decreased saccade amplitude. These findings provide insight into the gaze behavior of CVI subjects during visuospatial processing and visuomotor integration tasks that characterize functional vision impairments in this population.