Lotfi B. Merabet

Aim: To analyse the factorial structure of the Neonatal Assessment Visual European Grid (NAVEG), its diagnostic accuracy, the discriminative capacity of its individual items, and total score in detecting infants born preterm with neurological and/or brain ultrasound anomalies. Method: A total of 109 infants born preterm and 79 born at term underwent a visual function assessment using the NAVEG, a neurological examination based on the Amiel‐Tison Neurological Assessment (ATNAT), and, for infants born preterm, brain ultrasound imaging. Exploratory factor analysis, diagnostic accuracy, discriminative capacity, and differences in NAVEG scores among infants born preterm and at term were calculated. Results: The exploratory factor analysis revealed that 16 out of the 17 items in NAVEG accounted for 61% of the variance in a one‐factor solution model. Receiver operating characteristic curves demonstrated the discriminative capacity of NAVEG in detecting neurological signs for a total score of 3 or higher. Good levels of sensitivity and specificity were observed in infants born preterm, with ATNAT scores as reference (sensitivity 93.02%; specificity 78.79%) or in combination with brain ultrasound results (sensitivity 84.89%; specificity 83.93%). The most discriminative NAVEG items in detecting the presence of neurological signs in infants born preterm were oculomotor functions and visual field. Significant differences were found in the visual profiles of infants born preterm with neurological signs and/or brain ultrasound anomalies compared with those without these anomalies, and with infants born at term. Interpretation: NAVEG could be a useful screening tool in infants born preterm to evaluate visual dysfunctions and to detect those with neurological signs and/or brain ultrasound anomalies.

Walking safely through highly crowded environments is a significant challenge for individuals with cerebral visual impairment (CVI). Yet current ophthalmic examinations do not capture functional visual difficulties related to safe mobility. We developed an immersive virtual reality (VR)-based task that tracked eye gaze behaviors within dynamic areas of interest to assess pedestrian collision detection, avoidance, and associated visual scanning in CVI (n = 12) compared to control (n = 14) participants. Subjects walked through a simulated shopping mall populated with crowds of varying densities. The testing scenario was presented using a head-mounted display with integrated eye tracking, and locomotor, behavioral, and visual scanning responses were recorded. Compared to controls, CVI participants exhibited a slower mean preferred walking speed. They were also less likely and slower to detect target (colliding) pedestrians and were more likely to make a collision. CVI participants were also slower in making their first fixation and followed a larger visual scan path to find the target pedestrian. They also spent more time fixating on non-target compared to target pedestrians. Finally, CVI participants showed greater variability in their performance (including pathing deviations), reflecting a range of individual strategies, and maintained a larger walking safety margin (spatio-temporal envelope). These results provide objective evidence of mobility and associated gaze behaviors in CVI during navigation through highly crowded environments.

In this preliminary study, we investigated differences in visual search and spatial attention abilities between individuals with Cerebral Visual Impairment (CVI) and controls with neurotypical development using eye-tracking during a Star-Cancellation Task (SCT). Participants with CVI exhibited higher fixation counts overall compared to controls and showed little differentiation between fixating target and distractor AOIs, whereas controls showed a clearer preference for target AOIs. Fixation duration revealed stronger differentiation between target and distractor AOIs with controls for both Total Time and First Fixation Duration. These patterns suggest that individuals with CVI may demonstrate impaired allocation of selective attention towards task-relevant targets compared to controls. Given the sample size, these findings should be interpreted as preliminary and highlight the need for a larger sample.

Individuals with cerebral visual impairment (CVI) often struggle with visuospatial processing, particularly in highly cluttered or complex environments. These challenges are commonly assessed through visual search tasks, using global measures such as reaction time (RT), accuracy, and search area. Accordingly, impaired search performance in CVI manifests as longer RTs, lower accuracy, and broader search areas. However, rather than elucidating the underlying mechanism of the impaired search process, these measures decode its outcome. In the present study, we utilized eye-tracking data to compute detailed measures of fixation count and duration, aiming to characterize gaze pattern sequences and determine whether prolonged RTs in CVI stem from slower visual scanning or increased fixation counts. Our reanalysis of two previously published datasets reveals that longer RTs in CVI arise from elevated fixation counts, specifically on distractors, rather than from slower visual scanning. Our findings indicate recurrent disruptions in maintaining gaze on the target, likely reflecting difficulties in sustaining attention on the target, suppressing distractors, and preventing inhibition of return. Together, these findings highlight an inefficient search pattern that is more biased toward distractors than focused on targets. By revealing these underlying mechanisms, gaze-based measures offer a deeper understanding of visuospatial processing deficits in CVI.

Cerebral visual impairment (CVI) is a brain-based visual disorder associated with early injury and maldevelopment of visual processing pathways and areas. The clinical profile of visual dysfunctions observed in CVI is broad and complex. In this review, we discuss how visuospatial processing deficits represent a core feature of this condition, focusing on evidence from behavioral studies investigating complex motion processing and visual search abilities. Results from functional and structural neuroimaging studies have also provided important insight into putative neurophysiological mechanisms associated with these functional visual impairments. We propose that higher-order visual processing dysfunctions in CVI result from an impaired interplay between bottom-up (stimulus-driven) and top-down (goal-driven) processing mechanisms that leads to characteristic challenges in interpreting and interacting with the surrounding visual environment.

Individuals with cerebral visual impairment (CVI) often demonstrate difficulties with visual selective attention; however, the underlying neural mechanisms remain unclear. In this study, we investigated whether structural and functional connectivity between and within the attention networks, thalamus, and early visual areas is differentially associated with performance on a conjunction search task in participants with CVI as compared to controls. Data from 26 participants was collected and analyzed (10 CVI, four female, 17.4 years, 5.38 s.d., 16 control, 10 female, 22.25 years, 4.25 s.d.). White matter tracts associated with the dorsal and ventral attention networks as well as structural and functional connectivity matrices of the dorsal and ventral attention networks were generated for each participant. Group differences in conjunction search outcomes, tract volume, and network connectivity strength were evaluated. General linear models were used to investigate the relationship between neuroimaging predictor variables and each of the four conjunction search primary outcomes. All analyses were adjusted for age and verbal cognition. In the CVI group impaired visual search was associated with weaker structural and stronger functional connectivity, while in the control group the opposite effect was observed. Together, these results suggest that functional over-recruitment may be a maladaptive compensatory mechanism.

Visual imagery refers to the ability to create voluntary mental representations in the absence of corresponding visual stimuli, and current evidence suggests that it shares common neural mechanisms with visual perception. Cerebral visual impairment (CVI) is a brain-based visual disorder caused by early neurological injury and maldevelopment of central visual processing pathways and areas. Individuals with CVI often present with a complex visual profile, including deficits related to higher-order visual processing. However, the impact of visual maldevelopment on imagery abilities in this population has not been extensively characterized. We used the Vividness of Visual Imagery Questionnaire (VVIQ) to investigate visual imagery abilities in a cohort of CVI participants ( n = 25, mean age = 22.48 years ± 12.31 SD) compared to controls with neurotypical vision and development ( n = 25, mean age = 22.88 years ± 4.94 SD). We found that individuals with CVI had significantly lower VVIQ scores (mean = 41.84 ± 18.61 SD) than controls (mean = 62.48 ± 13.07 SD), after controlling for age and verbal IQ level. Within the CVI group, visual imagery abilities were not significantly different when separated by baseline visual acuity, gestational status, or co-occurrence of autism spectrum disorder. These results suggest that impaired visual imagery may represent an important feature characterizing the complex visual profile of CVI.