Including visual orienting functions into cerebral visual impairment screening: Reliability, variability, and ecological validity*

Background: Cerebral visual impairment (CVI) is a heterogeneous brain-based visual processing disorder in which basic visual orienting functions (VOF) and higher-order perception can be impaired. Aims: To evaluate (1) the test-retest reliability and variability of an eye tracking-based VOF paradigm, and related clinical characteristics, and (2) the relations between VOF (variability) and daily visual functioning and visuoperceptual dimensions. Methods and procedures: Thirty-three children with CVI (Males=14; mean age=9 years 10 months) underwent eye tracking thrice, completed a visuoperceptual battery, and parents completed the Flemish CVI questionnaire. VOF reliability and variability of reaction time (RTF), fixation duration and accuracy were assessed with intraclass correlation coefficient (ICC), Bland-Altman plots, and coefficient of variation. Relations were analysed with linear mixed models. Outcomes and results: Highly salient visual stimuli had good RTF reliability (ICCs=0.75) and triggered less variable VOF. Intermediate and low salience stimuli had poor-to-moderate reli-ability and triggered more variable VOF. Younger performance age related to more VOF vari-ability. Greater visual (dis)interest, clutter and distance viewing impairments, and a weaker visuoperceptual profile related to slower RTF. Conclusions and implications: Highly salient stimuli reveal a child's 'optimal' visual performance, whereas intermediate and low salience stimuli uncover VOF variability, which is a key CVI hallmark to detect.