Assessing visuospatial processing in cerebral visual impairment using a novel and naturalistic static visual search task

The relation between clutter and visual fatigue in children with cerebral visual impairment

PURPOSE

Cerebral visual impairment (CVI) is a brain-based condition which can be exacerbated by clutter. This study aimed to explore the relation between clutter and visual fatigue in children with CVI and evaluate the effectiveness of clutter algorithm metrics in assessing visual clutter in photographs of children's play areas and the relation to visual fatigue.

METHODS

Visual clutter was measured using algorithmic metrics, subjective observations by a clinical researcher (who also observed visual fatigue) and a Qualtrics survey.

RESULTS

Seventy-two children (mean performance age = 7 years 4 months) were included. Visual fatigue was present in over 90% of children. Results revealed a relation between clutter and visual fatigue observations (rs = 0.29; p = 0.01) and between visual clutter observations from researchers and Qualtrics participants (rs = 0.32; p = 0.02). Certain metrics were correlated with visual clutter observations (rs ranging from -0.30 to 0.51, p-values ranging from <0.001 to 0.03), but not with visual fatigue.

CONCLUSIONS

Children with CVI presented with visual fatigue, particularly in cluttered environments. Therefore, parents, caregivers, teachers and clinicians should be attentive to visual fatigue signs, as early recognition and intervention can help address the child's needs more effectively. Algorithms that effectively quantify visual clutter are valuable tools that can be integrated to enhance the assessment of clutter and its relation with visual fatigue to advance CVI research methodology. However, a clinician is required to assess visual fatigue and to obtain detailed information on environmental clutter, which algorithms alone may not fully capture. Finally, we recognise that visual fatigue and the impact of clutter should be integrated into psychoeducation and the comprehensive assessment of individuals with CVI.

Emulation of the subjective experience of visual dorsal stream dysfunction: a description of three in depth case studies

These case studies explore the subjective visual experiences of individuals with cerebral visual impairment (CVI), specifically dorsal stream dysfunction (DSD) characterized by simultanagnosia. Through three in-depth case studies, this work documents the challenges these individuals face when navigating cluttered environments. The individuals were asked to describe their visual experiences while watching videos of varying complexity, with the future aim of creating a simulation of simultanagnosia. This process revealed a dynamic constriction of their attentional visual fields as scene complexity increased, and vice versa. Notably, the volunteers experienced a phenomenon where their vision could "get stuck" on specific items, with an apparent concurrent reduction in their ability to perceive and describe visual information as visual clutter increased. These consistent observations indicate that the symptoms of simultanagnosia are not simply limited to perceiving one or two objects at a time but can vary dynamically in response to environmental complexity. They enhance our understanding of how DSD impacts visual search and perceptual experiences, prompting us to propose the term "simultanagnostic vision" to describe this more nuanced and dynamic manifestation of CVI. The results are critical for developing effective interventions and optimizing support strategies for individuals affected by DSD, particularly children at sensitive developmental stages. Furthermore, we recommend deeper investigation into how different visual processing streams in the brain interconnect and influence each other, which may open new avenues for targeted therapeutic interventions.

Gestalt, Navon and Kanizsa illusion processing in CVI, ADHD, and dyslexia Children with Normal verbal IQ

Introduction

Global Visual Selective Attention (VSA) is the ability to integrate multiple visual elements of a scene to achieve visual overview. This is essential for navigating crowded environments and recognizing objects or faces. Clinical pediatric research on global VSA deficits primarily focuses on autism spectrum disorder (ASD). However, in children with cerebral visual impairment (CVI) and other neurodevelopmental disorders (ADHD, dyslexia) similar deficits are reported. The aim of this study was to investigate global VSA performance in children with CVI, ADHD, dyslexia and neurotypical children by combing gaze-based measures with conventional neuropsychological tasks.

Methods

We included children aged 6-12 years with CVI (n = 20), ADHD (n = 30), dyslexia (n = 34) and neurotypical development (n = 37), all with normal verbal IQ. Eye tracking measurements were stepwise introduced within three global VSA tasks: Gestalt Closure (no eye tracking), Navon stimuli (eye tracking-based qualitative analysis) and Kanizsa Illusory Contours (KIC; eye tracking-based quantitative analysis). Verbal responses were compared with non-verbal gaze behavior.

Results

Children with CVI had significantly lower success rates on Gestalt Closure recognition, prolonged verbal response times on Navon stimuli, and decreased verbal and gaze performance on the KIC task compared to all other groups, irrespective of visual acuity. Children with ADHD and dyslexia performed similar to neurotypical children on all tasks.

Discussion

The results suggest а distinct global VSA deficit in children with CVI, which aligns with clinical observations of symptoms in daily life. Incorporating gaze-based analyses provided new information about search strategies beyond verbal answers and made the KIC task more inclusive for children with language and motor disabilities. Assessing global VSA within clinical CVI assessments could improve the differential diagnostic evaluations among children with CVI, ADHD and dyslexia, leading to more personalized treatment approaches.

The effectiveness of an individualised and adaptive game-based rehabilitation, iVision, on visual perception in cerebral visual impairment: A triple-blind randomised controlled trial

BACKGROUND

Cerebral visual impairment (CVI) can negatively affect a child's functioning, emphasising the need for interventions to improve visual perception (VP), potentially translating into improved health-related quality of life (HRQOL).

AIMS

Assessing the effectiveness of an adaptive individualised game-based rehabilitation, iVision, on VP, visual function, functional vision, and HRQOL.

METHODS AND PROCEDURES

Seventy-three children with CVI (3-12 performance age) were randomised into the adaptive individualised or the non-adaptive non-individualised group (3 sessions/week; 12 weeks). Primary outcome was change score (post-intervention - pre-intervention) of the lowest VP dimension. Key secondary outcomes included change score (post-intervention - pre-intervention) of visual function (reaction time to fixation in a preferential looking eye-tracking paradigm), functional vision (success rate in the adapted virtual toy box paradigm; total Flemish CVI questionnaire score), HRQOL (total scale score of the paediatric quality of life inventory 4.0 child self-report), and the lowest VP dimension change score (short-term follow-up - pre-intervention).

OUTCOMES AND RESULTS

Both groups significantly improved on the primary outcome, maintaining at short-term. Between-group differences were not significant. No significant effect was found for other key secondary outcomes. Exploratory analyses revealed VP dimension improvements and clinically meaningful HRQOL improvements.

CONCLUSIONS AND IMPLICATIONS

Although children with CVI improved their VP and to some extent HRQOL, no differences were found between the groups.

An evaluation of health-related quality of life and its relation with functional vision in children with cerebral visual impairment

BACKGROUND

Health-related Quality of Life (HRQOL) and its relation with functional vision is understudied in cerebral visual impairment (CVI).

AIMS

Characterising HRQOL, comparing child self- and parent proxy-reports, and exploring relations with functional vision.

METHODS AND PROCEDURES

Seventy-three children with CVI (n females = 33; n males = 40; Mean performance age = 7y2m) were included. HRQOL was measured with Pediatric Quality of Life Inventory (PedsQL) child self- and parent proxy-reports and compared using Wilcoxon signed-rank tests. Risk for impaired HRQOL was evaluated using cut-off scores. Parents scored functional vision using the Insight Questions Inventory and the Flemish CVI Questionnaire.

OUTCOMES AND RESULTS

61 % (self-reported) or 66 % of children (proxy-reported) were at-risk for impaired total HRQOL. Ratings were correlated (rs = 0.305; p = 0.013); however, children rated higher total HRQOL compared to parent-proxy (r = 0.382; p = 0.002). The Insight Questions Inventory and the PedsQL proxy-report were correlated (rp = -0.454; p < 0.001), the Flemish CVI Questionnaire was negligibly correlated (rp = -0.244; p = 0.041).

CONCLUSIONS AND IMPLICATIONS

HRQOL is reduced in CVI, and both child and parent perspectives are crucial. HRQOL and functional vision are intricately related, and impairment in one negatively affects the other.

Virtual Reality With Eye Tracking for Pediatric Ophthalmology: A Systematic Review

Virtual reality presents an efficient and engaging approach to ophthalmological diagnosis and treatment in children. This systematic review investigates the current state of eye tracking technology integrated into virtual reality for the spectrum of pediatric ophthalmology. The search encompassed the MEDLINE database via PubMed, without imposing any time restrictions. A total of 20 relevant studies that met our inclusion criteria were incorporated and categorized into the following domains: diagnosis, examination, treatment, and rehabilitation use of virtual reality devices within the realm of pediatric ophthalmology. Strabismus examinations and postoperative monitoring, inherited retinal degeneration examination and visual function testing, therapy of amblyopia, glaucoma visual field testing, cerebral visual impairment rehabilitation, and neuro-ophthalmic disease examination were included in the final analysis. Pediatric ophthalmology offers a promising landscape for the integration of eye tracking technology within virtual reality, with accelerated, quantifiable, and objective examination and diagnosis, and precise, real-time measurements that are crucial in children. Virtual reality is an engaging experience, easily applied in a pediatric setting and facilitating compliance during examination and adherence to therapy. Although our systematic review provides insights into the current state of research, it is anticipated that further exploration is required for the widespread utilization of eye tracking in virtual reality within pediatric ophthalmology. [J Pediatr Ophthalmol Strabismus. 2024;61(6):381-390.].

Impaired Visuospatial Processing in Cerebral Visual Impairment Revealed by Performance on a Conjunction Visual Search Task

Cerebral visual impairment (CVI) is a brain-based visual disorder associated with injury and/or maldevelopment of central visual pathways. Visuospatial processing impairments are a cardinal feature of the complex clinical profile of individuals with CVI. Here, we assessed visuospatial processing abilities using a classic conjunction search task. Twenty-three (23) individuals previously diagnosed with CVI (mean age 18.55 years ± 4.98 SD) and 37 controls with neurotypical development (mean age 21.11 years ± 4.56 SD) participated in the study. Subjects were instructed to search for a two-feature target (a white or black letter "O" or "C") presented among a varying number of surrounding distractors (set sizes ranging from 1 to 32 items). Behavioral outcomes collected were reaction time (RT), accuracy, as well as slope and intercept values derived from the RT x set size function. Overall, participants with CVI took longer and were less accurate in finding the target than controls. Analysis of RT x set size functions revealed a profile consistent with less efficient search and slower visual orienting responses as indexed by higher slope and intercept values, respectively. These results are consistent with clinical reports of impaired visuospatial processing abilities and deployment of visual selective attention in individuals with CVI.

Eyes on CVI: Eye movements unveil distinct visual search patterns in Cerebral Visual Impairment compared to ADHD, dyslexia, and neurotypical children

Visual search problems are often reported in children with Cerebral Visual Impairment (CVI). To tackle the clinical challenge of objectively differentiating CVI from other neurodevelopmental disorders, we developed a novel test battery. Visual search tasks were coupled with verbal and gaze-based measurements. Two search tasks were performed by children with CVI (n: 22; mean age (SD): 9.63 (.46) years) ADHD (n: 32; mean age (SD): 10.51 (.25) years), dyslexia (n: 28; mean age (SD): 10.29 (.20) years) and neurotypical development (n: 44; mean age (SD): 9.30 (.30) years). Children with CVI had more impaired search performance compared to all other groups, especially in crowded and unstructured displays and even when they had normal visual acuity. In-depth gaze-based analyses revealed that this group searched in overall larger areas and needed more time to recognize a target, particularly after their initial fixation on the target. Our gaze-based approach to visual search offers new insights into the distinct search patterns and behaviours of children with CVI. Their tendency to overlook targets whilst fixating on it, point towards higher-order visual function (HOVF) deficits. The novel method is feasible, valid, and promising for clinical differential-diagnostic evaluation between CVI, ADHD and dyslexia, and for informing individualized training.

Visuospatial processing in early brain-based visual impairment is associated with differential recruitment of dorsal and ventral visual streams

Visuospatial processing impairments are prevalent in individuals with cerebral visual impairment (CVI) and are typically ascribed to "dorsal stream dysfunction" (DSD). However, the contribution of other cortical regions, including early visual cortex (EVC), frontal cortex, or the ventral visual stream, to such impairments remains unknown. Thus, here, we examined fMRI activity in these regions, while individuals with CVI (and neurotypicals) performed a visual search task within a dynamic naturalistic scene. First, behavioral performance was measured with eye tracking. Participants were instructed to search and follow a walking human target. CVI participants took significantly longer to find the target, and their eye gaze patterns were less accurate and less precise. Second, we used the same task in the MRI scanner. Along the dorsal stream, activation was reduced in CVI participants, consistent with the proposed DSD in CVI. Intriguingly, however, visual areas along the ventral stream showed the complete opposite pattern, with greater activation in CVI participants. In contrast, we found no differences in either EVC or frontal cortex between groups. These results suggest that the impaired visuospatial processing abilities in CVI are associated with differential recruitment of the dorsal and ventral visual streams, likely resulting from impaired selective attention.

Visual search patterns during exploration of naturalistic scenes are driven by saliency cues in individuals with cerebral visual impairment

We investigated the relative influence of image salience and image semantics during the visual search of naturalistic scenes, comparing performance in individuals with cerebral visual impairment (CVI) and controls with neurotypical development. Participants searched for a prompted target presented as either an image or text cue. Success rate and reaction time were collected, and gaze behavior was recorded with an eye tracker. A receiver operating characteristic (ROC) analysis compared the distribution of individual gaze landings based on predictions of image salience (using Graph-Based Visual Saliency) and image semantics (using Global Vectors for Word Representations combined with Linguistic Analysis of Semantic Salience) models. CVI participants were less likely and were slower in finding the target. Their visual search behavior was also associated with a larger visual search area and greater number of fixations. ROC scores were also lower in CVI compared to controls for both model predictions. Furthermore, search strategies in the CVI group were not affected by cue type, although search times and accuracy showed a significant correlation with verbal IQ scores for text-cued searches. These results suggest that visual search patterns in CVI are driven mainly by image salience and provide further characterization of higher-order processing deficits observed in this population.