Methods for conceptualising 'visual ability' as a measurable construct in children with cerebral palsy

Assessment of Gaze Fixations and Shifts in Children with Cerebral Palsy: A Comparison of Computer- and Object-Based Approaches

Background/Objectives: Gaze behaviours, such as fixation on single objects, and switching gaze between two objects are important for signaling messages, making choices or controlling a computer for children with cerebral palsy (CP) and similar movement disabilities. Observing these behaviours can be challenging for clinicians, with a lack of agreement on how they can be objectively quantified or rated. Methods: This study compares two methods of eliciting and observing gaze behaviours: a computer presentation using an eye tracker and an object presentation scored by two independent observers in order to explore the utility of each to clinicians working in this area. Children with CP (n = 39) attempted single-target fixation (STF) and target-target fixation shift (TTFS) tasks using both presentations and the results were compared. Results: Six children were unable to calibrate the eye tracker to the accuracy level required. Significantly higher scores for both STF (81.3% object presentation and 30.3% computer presentation, p < 0.01) and TTFS (70.1% and 26.9%, p < 0.01) were seen on the object presentation, with children's performance not predicted by developmental age, severity of CP or presence or absence of strabismus. It is not possible to definitively state which method gives the "correct" result; however, the difference in reported success rate merits further discussion. Conclusions: Whilst eye tracking may present an "entry barrier" for some children in terms of its accuracy and calibration requirements, object presentation carries with it the risk of over-interpreting children as having fixated. Conversely, eye tracking may be better at recording fixations in children with strabismus, where object-based paradigms may offer more flexible administration for clinicians. The variability in children's performance on both presentations underlines the risk of assuming these skills to be present and the importance of assessing gaze behaviours in individual children.

Use of eye-gaze technology feedback by assistive technology professionals: findings from a thematic analysis

Purpose: Eye-gaze technology offers professionals a range of feedback tools, but it is not well understood how these are used to support decision-making or how professionals understand their purpose and function. This paper explores how professionals use a variety of feedback tools and provides commentary on their current use and ideas for future tool development.Methods and Materials: The study adopted a focus group methodology with two groups of professional participants: those involved in the assessment and provision of eye-gaze technology (n = 6) and those who interact with individuals using eye-gaze technology on an ongoing basis (n = 5). Template analysis was used to provide qualitative insight into the research questions.Results: Professionals highlighted several issues with existing tools and gave suggestions on how these could be made better. It is generally felt that existing tools highlight the existence of problems but offer little in the way of solutions or suggestions. Some differences of opinion related to professional perspective were highlighted. Questions about automating certain processes were raised by both groups.Conclusions: Discussion highlighted the need for different levels of feedback for users and professionals. Professionals agreed that current tools are useful to identify problems but do not offer insight into potential solutions. Some tools are being used to draw inferences about vision and cognition which are not supported by existing literature. New tools may be needed to better meet the needs of professionals and an increased understanding of how existing tools function may support such development.

Development and initial validation of a screening tool for visual ability/performance of people with polyhandicap

BACKGROUND

Visual impairments are common in people with polyhandicap although they are poorly assessed. However, evaluation of the visual abilities of these people is critical to determining treatment for impairments.

OBJECTIVES

To develop and validate an easy-to-use visual-behavioural scale for assessing the visual abilities of people with polyhandicap.

METHODS

The development of the Visual Assessment for People with Polyhandicap (VA-PLH) involved 2 steps: i) construction of the scale and ii) field validation. Participant selection criteria were aged > 3 years, age at onset of cerebral lesion < 3 years, a combination of motor impairment and profound intellectual impairment associated with restricted mobility (Gross Motor Function Classification System levels [GMFCS] III, IV or V), and everyday life dependence (Functional Independency Measure [FIM] <55). Vision assessment by both an orthoptist and an ophthalmologist was the reference against which were analysed the items of the scale completed by local health care workers. Acceptability, validity, and reliability were analysed.

RESULTS

Amongst the 232 participants included, 217 had a complete assessment, and 33% were < 18 years of age. Ocular abnormalities were reported in 83% of participants. Visual ability was altered or insufficient in 60% of participants. The final version of the VA-PLH included 3 items related to visual reaction (Area Under Curve Receiver Operating Characteristic = 0.83). Participants were considered at-risk if they had at ≥ 1 of 3 signs present (sensitivity 83% and specificity 73%). The scale's reliability was satisfactory CONCLUSION: The VA-PLH scale provides an easy-to-use, reliable and valid measure of visual status for people with polyhandicap and may be used both in clinical practice and clinical research. In addition, this study provides an overview of the diversity of visual impairments in a large population of people with polyhandicap, showing that most experience visual challenges.

Cerebral visual impairment and effect of phase-wise stimulation strategies-An interim analysis

Context

Cerebral visual impairment (CVI) is an overarching term, defined as a brain-based visual impairment with onset in childhood, unexplained by an ocular disorder and associated with unique visual and behavioral characteristics. Good vision and awareness of visual function in a child are highly essential as neuroplasticity is maximum in the first three years of life and response to intervention is utmost in this period. Awareness is lacking regarding CVI, and the diagnosis is largely missed. This can be easily addressed if a structured approach is employed.

Purpose

This study aims to evaluate the etiology and radiological correlation with the severity of CVI and outcome after structured intervention in children with CVI.

Settings and Design

Prospective-interventional study.

Methods and Material

Children attending the Child Development Centre (CDC) of a tertiary care hospital in North Karnataka and diagnosed with CVI in the age group of six months to 12 years and meeting the sampling criteria were screened and enrolled consecutively after obtaining parental consent/assent. Statistical analysis used is nonparametric test with SPSS software.

Results

Age showed a significant association with the phase of CVI. Perinatal insult was associated significantly with the severity of CVI. Magnetic resonance imaging (MRI) findings did not hamper the recovery of CVI.

Conclusions

Enrolment in early intervention programs tailored according to child's specific needs should be encouraged, with stress on ophthalmic screening of preterm and high-risk babies with perinatal hypoxia and history of convulsions, as early as six months.

Measure of Early Vision Use: development of a new assessment tool for children with cerebral palsy

PURPOSE

To report the development of an assessment tool to describe "how vision is used" for children with cerebral palsy.

METHOD

Measurement development consisted of three steps: (i) an online survey to explore the relevance and comprehensiveness of visual behaviours identified in a previous conceptualisation study; (ii) construction of items and a rating scale for the new measure; and (iii) cognitive interviews to explore comprehensibility and refine the measure in preparation for field testing. Survey respondents were 130 parents of children with cerebral palsy, eight adults with cerebral palsy, and 108 clinicians (n = 246). Nine parents participated in the interviews.

RESULTS

The new tool, the Measure of Early Vision Use, is a 14-item descriptive measure of typical performance of visual behaviours observable in everyday activities, as rated by parent/caregiver observation. Each item is rated on a 4-point ordinal scale.

CONCLUSIONS

This new measure is conceptually grounded within the Activity level domain of the International Classification of Functioning, Disability and Health as a measure of a single visual ability construct. The target population is children with cerebral palsy, and using parent report the Measure of Early Vision Use describes both strengths and limitations in using vision. This study addressed the selection of items and response options for the new scale, and provides evidence to support content relevance, comprehensiveness and comprehensibility from key stakeholders. Further research will explore psychometric properties and clinical utility.Implications for rehabilitationThe ability to use vision in daily activities is relevant to the development and learning of all children, so the availability of a method for describing visual abilities has potential for diverse research and clinical purposes.The Measure of Early Vision Use is a parent-report tool that provides a criterion-referenced method for quantifying and describing how children use vision in typical daily activities to support intervention planning.Clinicians and parents wishing to measure vision use in children with cerebral palsy can be confident about the rigorous methods used to develop this tool, including consultation with key stakeholders.

Measure of early vision use: initial validation with parents of children with cerebral palsy

PURPOSE

To report initial psychometric evidence on the Measure of Early Vision Use.

METHOD

Data on performance of the Measure of Early Vision Use scale were collected from 100 parents of children with cerebral palsy aged 0-12 years via online survey. Psychometric evaluation included assessment of scale dimensionality using Classical Test Theory and hypothesis testing for evidence of construct validity.

RESULTS

Principal components analysis of the 14-item parent-rated Measure of Early Vision Use revealed one component with an eigenvalue of 9.343, explaining 66.7% of variance; internal consistency was high (Cronbach's α = 0.96). Total scores ranged from 15-56 (Mean 42.8, standard deviation = 10.6). The results support seven pre-defined hypotheses including statistically significant differences in MEVU-total scores between children with and without parent-reported cerebral visual impairment.

CONCLUSIONS

Measure of Early Vision Use is the first assessment tool to describe 'how vision is used' in children with cerebral palsy. Results provide preliminary evidence that the measure comprises a unidimensional construct, sufficient construct validity, and feasibility as a parent-completed online assessment. Findings on internal structure provide foundational evidence and require further testing with Confirmatory Factor Analysis or Rasch Analysis.IMPLICATIONS FOR REHABILITATIONThe Measure of Early Vision Use is a new instrument to describe the use of basic visual abilities and is feasible to use as a parent-completed online questionnaire.The Measure of Early Vision Use is a unidimensional scale with sufficient construct validity to supports its use as a measure of 'how vision is used' without confounding visual ability with the reason why it might be impaired (e.g., cerebral vision impairment, motor limitations, or cognition).There is potential for the Measure of Early Vision Use to support early intervention planning for children with (or at high risk of) cerebral palsy.

Stakeholder consensus for decision making in eye-gaze control technology for children, adolescents and adults with cerebral palsy service provision: findings from a Delphi study

BACKGROUND

Limited research exists to guide clinical decisions about trialling, selecting, implementing and evaluating eye-gaze control technology. This paper reports on the outcomes of a Delphi study that was conducted to build international stakeholder consensus to inform decision making about trialling and implementing eye-gaze control technology with people with cerebral palsy.

METHODS

A three-round online Delphi survey was conducted. In Round 1, 126 stakeholders responded to questions identified through an international stakeholder Advisory Panel and systematic reviews. In Round 2, 63 respondents rated the importance of 200 statements generated by in Round 1. In Round 3, 41 respondents rated the importance of the 105 highest ranked statements retained from Round 2.

RESULTS

Stakeholders achieved consensus on 94 of the original 200 statements. These statements related to person factors, support networks, the environment, and technical aspects to consider during assessment, trial, implementation and follow-up. Findings reinforced the importance of an individualised approach and that information gathered from the user, their support network and professionals are central when measuring outcomes. Information required to support an application for funding was obtained.

CONCLUSION

This Delphi study has identified issues which are unique to eye-gaze control technology and will enhance its implementation with people with cerebral palsy.

Visual Function Classification System for children with cerebral palsy: development and validation

AIM

To develop and validate the Visual Function Classification System (VFCS), which was created to classify how children with cerebral palsy (CP) use visual abilities in daily life.

METHOD

The process of development and validation of the VFCS involved four phases: (1) drafting of the five levels from the analysis of literature and clinical experience; (2) validation of constructs and revision of the levels for concept meaningfulness, using nominal group process; (3) refinement by international Delphi survey; and(4) assessment of interrater reliability among professionals and with caregivers, and of test-retest reliability.

RESULTS

Five nominal groups involved 29 participants; 65 people completed the first round and 51 the second round of the Delphi survey. Construct validity was demonstrated within an expert group and external validation through several stakeholders, with the involvement of patients and families to ensure meaningfulness of the concept. Discussions continued until consensus was reached about the construct and content of the five levels. Participants in the reliability study included 29 professionals, 39 parents, and a total sample of 160 children with CP (mean age [SD] 6y 6mo [3y 4mo]; median 5y 7mo, range 1-19y). Absolute interrater agreement among professionals was 86% (weighted κ=0.88; 95% confidence interval [CI] 0.83-0.93). Test-retest reliability was high (weighted κ=0.97; 95% CI 0.95-0.99). Parent-professional interrater reliability on 39 children was moderate (weighted κ=0.51; 95% CI 0.39-0.63).

INTERPRETATION

The VFCS has been appropriately constructed and provides a reliable system to classify visual abilities of children with CP both in clinical and in research settings.

WHAT THIS PAPER ADDS

The Visual Function Classification System is a valid and reliable system. It classifies visual abilities of children with cerebral palsy in clinical and research settings. At a clinical level, it can be used to harmonize communication among professionals and identify patients' strengths and weaknesses. In research settings, it can be used to stratify patients, define natural history evolution, and interpret intervention studies.