Vision-Based Assistive Technologies for People with Cerebral Visual Impairment: A Review and Focus Study

Disentangling How the Brain is “Wired” in Cortical (Cerebral) Visual Impairment

Commentary: Profiling Children With Cerebral Visual Impairment (CVI) Using Multiple Methods of Assessment to Aid in Differential Diagnosis

To estimate how many children in mainstream primary schools have cerebral visual impairment (CVI)-related vision problems and to investigate whether some indicators might be useful as red flags, if they were associated with increased risk for these problems. We conducted a survey of primary school children aged 5 to 11years, using whether they were getting extra educational help and/or teacher- and parent-reported behaviour questionnaires to identify children at risk for CVI. These and a random 5% sample were assessed for CVI-related vision problems. We compared the usefulness of potential red flags using likelihood ratios. We received questionnaires on 2298 mainstream-educated children and examined 248 children (152 [61%] males, 96 females [39%]; mean age 8y 1mo, SD 20mo, range 5y 6mo-11y 8mo). We identified 78 out of 248 children (31.5% of those examined, 3.4% of the total sample), who had at least one CVI-related vision problem. The majority (88%) were identified by one or more red flag but none were strongly predictive. Fewer than one in five children with any CVI-related vision problem had reduced visual acuity. Children with CVI-related vision problems were more prevalent than has been appreciated. Assessment of at-risk children may be useful so that opportunities to improve outcomes for children with CVI-related vision problems are not missed.

Cortical or cerebral visual impairment (CVI) is a leading cause of pediatric visual impairment. However, there are limited data using validated assessments of vision-specific quality of life (VS-QOL) in these patients. The purpose of this study was to assess VS-QOL in children with CVI using the Children's Visual Function Questionnaire (CVFQ). Children with CVI (ages 12 months to 12 years) were prospectively recruited from a single pediatric neuro-ophthalmology clinic at a children's hospital, where a complete ophthalmologic examination was performed. Age-matched typically developing controls were recruited from a web-based recruitment service. Parents of participants completed the CVFQ. Overall and subscale CVFQ scores were compared between children with CVI and controls. Additionally, CVFQ scores were correlated with clinical findings in children with CVI. Forty-three children with CVI and 20 controls were included in this study. CVFQ overall and all subscale scores were significantly lower in children with CVI (p < .0001). Among CVI participants, there was a borderline association between visual acuity and CVFQ overall and competence subscale (both p = .07) scores. CVI patients with strabismus had significantly worse scores on the family impact subscale than those without strabismus (p = .04). CVI profoundly affects VS-QOL in individuals with CVI. Strabismus and CVI may have an additive impact on families. Additional studies are needed to determine whether measures of functional vision correlate with VS-QOL in children with CVI, and also to develop VS-QOL scales that are specific to concerns of families and children with CVI. All members of the multidisciplinary care team for individuals with CVI should be aware of the effect of this diagnosis on VS-QOL in both the child and family. Ultimately, practitioners and researchers should strive to identify interventions to improve VS-QOL in individuals with CVI.

PurposeCerebral Visual Impairment (CVI) is the leading cause of paediatric visual impairment in developed countries. Earlier diagnosis provides access to early intervention, which may improve visual function, functional vision and developmental outcomes. The purpose of this study was to determine the age and timing of CVI diagnosis and the severity of CVI.MethodA retrospective review of medical records was completed. Children with CVI were identified by billing diagnosis codes at a single centre from 1 January 2008 to 1 March 2018. CVI severity was determined using the CVI Range Rating 2. Linear regression assessed the effect of diagnosis timing on CVI Range scores as the dependent variable, adjusting for age.ResultsOne hundred and ninety‐four children with CVI met inclusion. The mean age at the initial ophthalmology visit was 3.6 ± 4.4 years (6 weeks to 20 years 4 months). The mean age at CVI diagnosis was 4.6 ± 4.7 years (9 weeks to 20 years 4 months) and the mean time from first ophthalmology visit to diagnosis was 1.0 ± 1.9 years (0 days to 9 years 2 months). Earlier diagnosis was associated with more severe CVI. Sixty percent of children (116/194) were assessed with the CVI Range. Those with lower range scores (i.e., more severe CVI) were more likely to be diagnosed at the first visit. Delayed diagnosis was more common in children with higher range scores (milder CVI).ConclusionsIdentification of CVI in children is often delayed in the absence of significant vision impairment. Early screening, assessment and diagnosis are critical to ensure access to early intervention and adaptations that may improve visual function and quality of life. Frequent screenings for young children at risk for CVI using validated screening questionnaires, along with targeted history taking and the development of sensitive assessment tools, should be a research priority.

PP06.1 – 2574: Aetiologies of CVI in Mainstream Secondary Education

Aim: To determine whether the level of gross motor function and functional skills in children with cerebral palsy (CP) and cerebral visual impairment (CVI) as well as caregiver assistance are lower in comparison with the corresponding group of children experiencing CP without CVI. Method: Data aggregated from 23 children experiencing CP with CVI were compared with data from children with CP without CVI matched for Gross Motor Function Classification System, mental development and age at testing. Scores for Gross Motor Function Measure-88 (GMFM-88) and the Pediatric Evaluation of Disability Inventory-NL (PEDI-NL) were employed to compare the level of gross motor function, functional skills and caregiver assistance between both groups. The Wilcoxon Signed Rank Test was utilized with a significance level of p < 0.05. Results: Children with CP with CVI, mean (± SD) age 6.4 ± 1.5, scored significantly lower than those with CP without CVI, mean age 6.3 ± 1.6, on all GMFM-88 dimensions and the total score (p < 0.001) and on the PEDI-NL in the sections of Functional Skills and Caregiver Assistance as well as in those of domains self-care (p < 0.001), mobility (p < 0.001) and social functioning (p < 0.001). Concerning the modifications scale, the scores for children with CP and CVI were significantly lower regarding mobility (no modification, p < 0.05), social functioning (no modification, p < 0.05) and social functioning (child-oriented, p < 0.05). Conclusion: CVI contributes to diminished gross motor function and functional skills in children experiencing CP with CVI compared with children with CP without CVI. Children with CP and CVI also require increased support at the level of caregiver assistance. Specific interventions need to be developed for children experiencing CP with CVI in order to improve gross motor function, functional skills and caregiver assistance.

Introduction: Cortical or cerebral visual impairment (CVI) is the leading cause of bilateral visual impairment in developed countries. The goals of this study were to explore the CVI education and training received by occupational therapy practitioners and teachers of students with visual impairments and to quantify the confidence of these professionals to evaluate and work with children who are diagnosed with CVI. Methods: An Internet-based survey was conducted with a volunteer sample that included occupational therapists, certified occupational therapy assistants, and certified teachers of students with visual impairments who practice in 50 U.S. states; Washington, D.C.; and Canada. The survey was posted on professional organizations and social media websites, as well as emailed to colleagues at organizations such as the Association for the Education and Rehabilitation of the Blind and Visually Impaired, schools for students who are blind, and local universities. Data collection occurred between June 2019 and November 2019. Results: Surveys were completed by 205 respondents from 43 U.S. states; Washington, D.C.; and Canada. Occupational therapy practitioners consistently reported lower rates of formal education in CVI, with only 25% of occupational therapists and 47% of certified occupational therapy assistants receiving education on CVI in their academic programs. Less than 23% of occupational therapists received training on CVI assessments, whereas 75% of teachers of students with visual impairments had training in CVI assessments. Additionally, respondents indicated reduced satisfaction with their knowledge and skills for treating or teaching children with CVI. Discussion: The results indicate a gap in formal CVI education for occupational therapy practitioners and, to a lesser extent, teachers of students with visual impairments. Due to the increasingly high prevalence of CVI, the gap in formal education on CVI is significant. Implications for Practitioners: Results indicate the need to increase formal and continuing education for occupational therapy practitioners and teachers of students with visual impairments.

Cerebral Visual Impairment (CVI) is the most common form of childhood visual impairment. Yet it remains the least well understood by parents and professionals alike. There is an urgent need to provide a bridge between academic knowledge concerning CVI, and to give a practical understanding of the condition to those affected, parents, carers, and professionals alike so that a common language can be shared between patients, their carers and professionals. The wide ranging manifestations of CVI, and the lack of accessible well recognised terms to describe it, render it difficult to understand how someone with their own unique form of CVI actually “sees”. However, with graded progressive explanation, knowledge can be gained, leading to an understanding of the visual effects of CVI from the perspective of those affected. The current position of limited understanding of the condition presents a major challenge for health and education professionals: How does one bring about the requisite CVI literacy, to render the subject accessible to families, affected children and adults, and the public?One way of doing this is by means of a plain language, multi-media resource, hosted on a publicly available website, driven by a partnership of adults with CVI, parents of children with the condition and experienced professionals from around the world, including those from the vision sciences and education. Within this context, we have explored the website resource of the not-for-profit organisation CVI Scotland (https://cviscotland.org/). This comprises a growing body of CVI knowledge created for teaching, sharing, learning and developing knowledge and understanding. By analysing anonymised data concerning the activity of 80,000 users from 170 countries, we have examined where the users who are accessing the website come from, what users are seeking in terms of information, how they have accessed the website, and what devices they use. The results are interpreted though frequency analysis and linear regression. Based on this analysis several recommendations are made in terms of disseminating information about CVI to members of the public as well as developments to enhance the website itself. To our knowledge this is the first study to examine the use of a website dedicated to CVI using Google analytics.

Diagnostic sensitivity and specificity of the teach CVI screening tool for identifying cerebral visual impairment in children.

Validation of clinical tools to measure grating acuity and contrast sensitivity in children with cerebral visual impairment.

To investigate the underlying factor structure of the 46-item Flemish cerebral visual impairment (CVI) questionnaire, differentiate the factor scores of children with and without CVI, and examine the impact of comorbidities on factor scores. The records of 630 children (386 males, 244 females; median age 77mo; interquartile range 63-98mo) who visited the CVI clinic and the Centre for Developmental Disabilities at the University Hospitals of Leuven from 2001 to 2018 were reviewed systematically. Inclusion criteria included an up-to-date questionnaire, a definitive diagnosis, and clinical assessment. Three hundred and forty-five children (179 with CVI [108 males, 71 females; median age 74mo; interquartile range 61-93mo] and 166 without CVI [110 males, 56 females; median age 88mo; interquartile range 70-107mo]) were included. An exploratory factor analysis resulted in a 5-factor (object and face processing impairments; visual (dis)interest; clutter and distance viewing impairments; moving in space impairments; and anxiety-related behaviours) biologically and clinically plausible model, which retained 35 items and explained 56% of the total variance. Mann-Whitney U tests indicated that factors 1 to 4 were significantly higher in children with CVI compared to children without CVI (p-values ranged from p<0.001 to p<0.05; effect sizes ranged from 0.11 to 0.33); factor 5 showed no differences. Autism, developmental coordination disorder, epilepsy, and cerebral palsy impacted factor scores. A 5-factor structure of the Flemish CVI questionnaire differentiates children with and without CVI. Comorbidities should be accounted for when researching CVI. Cerebral visual impairment (CVI) is characterized by impaired object and face processing and impaired visual interest. CVI is also characterized by impaired clutter and distance viewing, and impaired moving in space. All children (with or without CVI) demonstrated anxiety-related behaviours. Autism affected object/face processing, whereas developmental coordination disorder, epilepsy, and cerebral palsy affected visual interest.

The brain is intricate in its design and function. Neuroscientists and neuropsychologists are revamping concepts and principles that are related to brain function and vision as more information is obtained and understood. The changes that are emerging from brain research are altering our understanding of cortical or cerebral visual impairment (CVI) in children. In addition, injury to the brain can result in functional manifestations that are complex and multifaceted. These functional manifestations are related to the extent, location, and time of onset of the brain lesions, but the precise effects of these injuries cannot be readily and fully predicted in children from the brain lesions themselves. For example, we have no idea of the ways in which areas of the brain that are intact in young children who have brain damage assume the functions of damaged areas owing to the plasticity of the brain. Thus, an understanding of recovery mechanisms for CVI in children and of the effects of intervention is in its infancy. As a result, our understanding of the nature of CVI in children must be open and flexible as we incorporate and learn to apply an ever-evolving knowledge base. We must understand the issues surrounding CVI, embrace their complexity and lack of closure, and determine directions for the effective diagnosis and treatment of children with CVI from medical and educational perspectives. WHAT IS CVI? The story of CVI that is due to brain injury began in the late 19th century with the emergence of the concept that vision was associated with brain function, most notably with the operations of the occipital cortex. As Hoyt (2003) noted, permanent field loss came to be associated with damage to the visual cortex through work conducted by neurologist Gordon Holmes with veterans who were injured during World War I. There were puzzling discrepancies even at that time, since Gordon Riddoch, of the Royal Army Medical Corps, found that some World War I veterans with injuries to the occipital cortex could perceive motion in their visual field. This ability to detect motion as well as other visual events in the nonseeing visual field has been called blindsight. Blindsight is awareness of moving targets, lights, and colors in the blind area, and this awareness can be either conscious or subconscious (called statokinetic dissociation or the Riddoch phenomenon in adults). It is difficult to determine in children because of their young age and co-occurring impairments (Boyle, Jones, Hamilton, Spowart, & Dutton, 2005). Before the 1980s, the absence of sight that is due to bilateral damage to the occipital cortex was called cortical blindness. This term was derived from studies of adults, but was applied to children as well. Cortical blindness, however, was considered to be rare in children, according to Hoyt (2003). Many children with visual impairments that were due to brain damage recovered their visual function and were not totally blind (Hoyt, 2003; Whiting et al., 1985). In the late 1980s, the term cortical blindness gave way to the term cortical visual impairment or CVI. At that time, the generally accepted definition of CVI was damage to the visual system between the lateral geniculate nucleus and the visual cortex. A reduction in visual acuity was the way that CVI was identified (Jan & Groenwald, 1993). Basically, the eyes appeared to be normal, yet there was diminished visual acuity because of a diagnosed brain damage. Later, it became more common in the literature to find that CVI often co-occurred with other visual conditions, as was mentioned earlier (Good, Jan, Burden, Skoczenski, & Candy, 2001). Visual behaviors and perception related to damage to other areas in the brain were not considered cortical, and thus children with damage outside the cortex were not included under the CVI umbrella. As researchers learned more about brain damage and visual impairment, they found that periventricular leukomalacia (PVL), damage to the white matter surrounding the ventricles in the brain, was a common cause of visual impairment in children who were born preterm (Jacobson, Lundin, Flodmark, & Ellstrom, 1998). …

Introduction: Cerebral visual impairment (CVI) is the most common cause of visual impairment in developed nations. The purpose of this study was to understand the entry-level education and training received by optometrists and ophthalmologists, as well as current practice patterns. Methods: Online surveys were distributed to optometry and ophthalmology program directors and practicing optometrists and ophthalmologists. Data collection occurred between May 2020 and August 2020. Results: Surveys were completed by 48 program directors and 334 eye care professionals in North America, Europe, Oceania, and Asia, with most in North America. Less than half of the program directors reported (48%, 23/48) providing formal CVI didactic education. No program provided more than 2 hr of classroom instruction, 83% offered 1–2 hr, and 17% offered less than 1 hr. Although some clinical instruction was offered by 92% (44/48) of programs, exposure to patients with CVI occurred infrequently. Over one-half of the practitioners reported moderate familiarity with CVI. However, only 31% (102/334) of practitioners reported receiving formal classroom CVI instruction; of those, 56% (57/102) had 2 hr or less. Sixty-five percent (218/334) reported diagnosing children with CVI infrequently in their practices, with only 24% making CVI diagnoses on a daily or weekly basis. Discussion: Given the diverse and heterogenous characteristics of CVI, it is challenging to prepare future clinicians to evaluate and manage children with CVI with only 1–2 hr of lecture and minimal clinical exposure. This missed opportunity during formal education has significant implications for early diagnosis and timely intervention. To adequately prepare practitioners for comprehensive care of individuals with CVI, it is imperative to improve the quality and scope of didactic and clinical training. Implications for Practitioners: The results indicate the need for more comprehensive CVI education for optometrists and ophthalmologists during training as well as throughout practice with continuing education.

IntroductionCerebral Visual Impairment (CVI) is the most common cause of visual impairment in children in the developed world and appears to be more prevalent in children with additional support needs (ASN). There is an urgent need for routine screening for CVI, particularly in children with ASN, however, current screening questionnaires for CVI have limited validation. The aim of this study was to evaluate two screening tools: the Five Questions and the CVI Questionnaire. Additionally, the distribution of CVI across neurodevelopmental disorders is unknown. This too was investigated.MethodsAn online survey was completed by 535 parents. The survey was advertised via social media, CVI websites and parent email systems of four schools. The survey comprised of the Five Questions, the CVI Questionnaire and additional questions regarding the child’s diagnoses. Whether or not a child had a diagnosis of CVI and/or additional neurodevelopmental disorders was based on parental report.ResultsBased on parent reports, both the screening tools accurately screened for CVI diagnoses in children. The Five Questions and the CVI Questionnaire have construct validity (as determined through factor analysis), high internal consistency (as determined by Cronbach’s alpha) and convergent validity (as determined by correlation analysis of the raw scores of each questionnaire). This study also highlights that among children with neurodevelopmental disorders, a large proportion have parent-reported CVI (23%-39%) and potential CVI (6.59–22.53%; as identified by the questionnaires).ConclusionThe current study demonstrates that the Five Questions and CVI Questionnaire have good convergent validity, internal consistency and a reliable factor structure and may therefore be suitable as screening tools. The study also highlights that reported or potential CVI is evident in a large proportion of children with neurodevelopmental disorders.