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Developmental Neurorehabilitation

ISSN: 1751-8423 (Print) 1751-8431 (Online) Journal homepage: https://www.tandfonline.com/loi/ipdr20

A systematic review investigating outcome measures and uptake barriers when children and youth with complex disabilities use eye gaze assistive technology

Erin Perfect, Elizabeth Hoskin, Samantha Noyek & T. Claire Davies

To cite this article: Erin Perfect, Elizabeth Hoskin, Samantha Noyek & T. Claire Davies (2019): A systematic review investigating outcome measures and uptake barriers when children and youth with complex disabilities use eye gaze assistive technology, Developmental Neurorehabilitation, DOI: 10.1080/17518423.2019.1600066

To link to this article: https://doi.org/10.1080/17518423.2019.1600066

Published online: 16 Apr 2019.

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A systematic review investigating outcome measures and uptake barriers when children and youth with complex disabilities use eye gaze assistive technology Erin Perfect a, Elizabeth Hoskin a, Samantha Noyek a,b, and T. Claire Davies a

aBuilding and Designing Assistive Technologies Lab, Department of Mechanical and Materials Engineering, Queen’s University, Kingston, Canada; bSchool of Rehabilitation Therapy, Queen’s University, Kingston, Canada

ABSTRACT Children with complex disabilities sometimes have difficulty communicating with their parents, care- givers, and teachers. For these children, eye gaze assistive technology can be used to facilitate commu- nication. Eye gaze assistive technology outcomes for children and youth were analyzed in this systematic review. Database and hand-searches yielded 4412 unduplicated results, of which 11 articles were eligible for this review. Outcome measures, as well as environmental and personal factors, were mapped to the World Health Organization’s International Classification of Functioning, Disability and Health framework. Communication outcomes were most prevalent and co-occurred with outcomes in all reported activities and participation domains. Environmental and personal factors were classified as either facilitators or as barriers in relation to device uptake and success. Although comprehensive professional and caregiver support was the primary facilitator for success, barriers could lead to rejection of the technology even when children were successful using the system.

ARTICLE HISTORY Received July 4, 2018 Revised March 4, 2019 Accepted March 23, 2019

KEYWORDS Assistive technology; augmentative and alternative communication; children; eye gaze; eye tracking

Introduction

There are children and youth worldwide with complex dis- abilities who are unable to communicate through conven- tional means.1 Without speech or other robust forms of communication, it can be difficult for these children to com- municate with their parents, caregivers, and teachers. When head and limb movements are affected, access to suitable augmentative and alternative communication (AAC) devices is limited.1 Research has shown that children with limited communication abilities and profound physical impairments are restricted in societal participation2 and have limited opportunities for social interaction.3 For these children, access to a computer can create opportunities for communication and societal participation as well as other recreation activities.4 When traditional computer access devices such as mouse, keyboard, joystick, touch screen, or switch, are unsui- table, eye gaze assistive technology may provide access to a computer.5 Eye gaze assistive technology has become a viable and reliable computer access method and AAC intervention6,7 This technology can empower individuals by enhancing communication opportunities and enabling them to engage in a variety of educational and recreational activities.8,9

Eye gaze assistive technology typically consists of an eye tracker (which uses specialized infra-red video cameras) mounted to the bottom of a tablet or computer monitor as well as specialized AAC software.1 To operate the eye tracker, the individual must have voluntary eye-movement control.

The individual can make selections or ‘click’ either by holding their gaze for a predefined period of time (‘dwell’), blinking, or activating an external switch or button. However, there is a significant learning curve associated with eye gaze assistive technology and for individuals with complex disabilities, acquisition of eye gaze skills may take several months to a year.10

Individuals who use eye gaze assistive technology are diverse and may have any combination of physical and/or cognitive impairments. While one child with a particular health condition is successful using eye gaze assistive technol- ogy, another with the same condition may face greater diffi- culties using eye gaze assistive technology. For communication technology uptake to be successful, it is cri- tical that the functionality of the system be appropriate for the motor, cognitive, and sensory skills of the individual. This requires ongoing support from health-care professionals, par- ticularly in the initial stages of language and literacy skill development.11 Support from family members and caregivers is also critical. When the family or caregiver is involved with the individual in the process of matching a technology, it is less likely the system will be abandoned.4,12

A systematic review conducted by Karlsson et al. examined the effectiveness of eye gaze assistive technology at facilitating communication for children and adults.1 The review included two articles; the first reported communication outcomes for children with cerebral palsy,13 and the second reported greater quality of life and reduced depression among adults with

CONTACT T. Claire Davies [email protected] Building and Designing Assistive Technologies Lab, Department of Mechanical and Materials Engineering, Queen’s University First authorship is shared between Erin Perfect and Elizabeth Hoskin. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/ipdr.

DEVELOPMENTAL NEUROREHABILITATION https://doi.org/10.1080/17518423.2019.1600066

© 2019 Taylor & Francis Group, LLC

amyotrophic lateral sclerosis.14 Karlsson et al. found no out- comes specific to eye gaze assistive technology or assistive technology.1 However, the authors identified the recently developed AAC Therapy Outcome Measures (TOMs)15 as a potentially suitable instrument to measure satisfaction and evaluate the effectiveness of eye gaze assistive technology.1

Karlsson et al. recommended that “in relation to outcome measurement, measures of participation and quality of life should be explored to identify whether successful eye-gaze control technology used to access a computer has an impact on these important domains”.1 The present systematic review addresses the recommendations of Karlsson et al. by classify- ing outcomes of eye gaze assistive technology research with respect to their impact on domains of activities and participa- tion under the International Classification of Functioning, Disability, and Health.

ICF Framework

The International Classification of Functioning, Disability, and Health (ICF) is a framework for describing and organiz- ing information on functioning and disability. The ICF frames the understanding of disability through its multi-faceted aspects, minimizing the risk of solely defining an individual by their disability.16 The ICF is organized into two parts. Part one addresses functioning and disability based on the compo- nents of body functions and structures, and, activities and participation. Part two covers contextual factors, classified as either environmental factors or personal factors.16 There are no known studies that use the ICF framework to explicitly assess technology outcomes when using eye gaze assistive technology for children and youth. For this review, two com- ponents of the ICF are of interest: activities and participation domains, and contextual factors.

Under the ICF framework, the activities and participation domain is influenced by and affects the framing of the indivi- dual’s health and/or disability, body function/structures, and personal/environmental contextual factors. The activities and participation domain covers nine subdomains including: (i) communication, (ii) community, social, and civic life, (iii) domestic life, (iv) general tasks and demands, (v) interpersonal interactions and relationships, (vi) learning and applying knowl- edge, (vii) major life areas, (viii) mobility, and (ix) self-care.16

Although individuals who use eye gaze assistive technology are diverse, there are some commonalities across individuals. Regardless of health condition(s) and/or physical or cognitive impairment(s), the impact and interaction effects on body function/structures of the individual has resulted in signifi- cant challenges for the individual in every domain associated with activities and participation. As such, children and youth with complex disabilities often rely on a caregiver to assist them to play, communicate, and perform most other daily activities.7,17

The ICF contextual factors categorize and contextualize an individual’s health and disability within their environment. There are five environmental factors defined by the ICF: (i) attitudes, (ii) the natural environment and human-made changes to the environment, (iii) products and technology, (iv) services, systems, and policies, (v) and support and

relationships. Personal factors are not explicitly defined by the ICF but in the context of this systematic review, any external factors pertaining to the individual that were not adequately described by environmental factors were consid- ered personal factors. These environmental factors and perso- nal factors may facilitate or impede technology uptake and success.

Objectives

The objectives of this systematic review were to classify eye gaze assistive technology outcomes using the ICF framework, and to identify barriers and facilitators of eye gaze assistive technology success and uptake by children and youth with complex disabilities. The findings of this review can help inform engineering design of assistive technology as well as prescription and training in rehabilitation science/occupa- tional therapy. Furthermore, this review can also serve as a guide for other researchers applying the ICF framework to the assessment of assistive technology.

Method

This systematic review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.18 The researchers assessed (i) study characteristics, (ii) participant characteristics, (iii) methodo- logical quality, (iv) activities and participation outcomes, and (v) contextual factors influencing eye gaze assistive technology success and uptake.

Eligibility Criteria

The objectives were framed using the PICO model of popula- tion, intervention, comparison, and outcome.18 Only peer- reviewed, English-language articles were considered for inclu- sion in this systematic review. Studies were excluded if they (i) were systematic reviews, (ii) used eye gaze for diagnostic pur- poses, (iii) did not report participant outcomes, or (iv) did not meet the eligibility criteria defined for each PICO category.

Population The population of interest was defined as school-aged chil- dren and youth who do not use functional speech, generate writing, or use any other typical forms of language. This includes communication through facial expressions, limited vocalizations (typically ‘yes’ or ‘no’), AAC, eye pointing, or challenging behaviors. School-aged was defined as ages 4–21 years because, in many countries, children and youth with disabilities are able to access primary and secondary education until the age of 21.19–21

Intervention The intervention was defined as eye gaze assistive technology. Studies were included if participants intentionally and volun- tarily interacted with an eye gaze assistive technology system to control a software program. Studies were excluded if the focus was passive eye gaze where the participant was not

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intentionally interacting with or controlling their virtual environment using the eye gaze system.

Comparison The comparison was defined as the use of eye gaze assistive technology as compared to the absence of eye gaze assistive technology use.

Outcomes The outcomes were defined as activities or tasks completed using eye gaze assistive technology which can be mapped to the ICF activity and participation domains, as well as environmental and personal factors impacting device uptake and success.

Information Sources

During February 2018, a search of seven academic databases including Cumulative Index to Nursing and Allied Health Literature (CINAHL) via EBSCOhost; Excerpta Medica Database (Embase) via OvidSP; Engineering Village; MEDLINE via OvidSP; PsycINFO via OvidSP; REHABData; and Web of Science Core Collection was conducted. Additionally, the Tobii eye tracking library (https://www. diigo.com/profile/Tobiieyetracking) and COGAIN gaze inter- action bibliography article collection ‘eye-controlled systems and gaze-based interaction for people with disabilities’ (http:// wiki.cogain.org/index.php/Bibliography_Gaze_Interaction) were hand searched.

Search

For all OvidSP databases, the following three search categories were paired with the Boolean term AND to combine primary concepts of interest; (eye gaze assistive technology search terms) AND (child and youth search terms) AND (non-verbal search terms). Each keyword was searched with its synonyms to describe the concept to its greatest extent. The specific search terms applied are provided in Table 1. The search strategy was adapted to include database-specific subject headings for CINAHL (via EBSCOhost) and topic, research area, and category headings for Web of Science Core Collection. For Engineering Village, a text string search that incorporated subject headings from the OvidSP search strategy as keywords was conducted. For REHABData, due to the limited options in search structure, three separate searches each requiring a single technology search term used in the OvidSP search was conducted. The Tobii and COGAIN collections were hand searched. Database searches were supported through addi- tional hand-searches from other sources as well as bibliographies of full-text articles included in the review.

Study Selection

Relevant studies were selected after two-stages of independent review had been conducted by at least two researchers. During the first stage, titles and abstracts were assessed for eligibility. During the second stage, the full text of studies previously identified was assessed for eligibility criteria. At each stage of the review, studies were sorted into ‘Yes’, ‘No’, and ‘Maybe’

Table 1. OvidSP database search terms.

Technology search terms Child and youth search terms Non-verbal search terms

(‘eye track*’ OR ‘eye gaz*’ OR ‘eye mouse’)

(‘child*’ OR ‘youth’ OR ‘boy*’ OR ‘girl*’ OR ‘juvenile’ OR ‘kid*’ OR ‘teen*’ OR ‘young adult*’ OR ‘school age*’ OR ‘young person*’ OR ‘young people’ OR ‘adolescent*’ OR ‘pediatric*’)

(((‘motor skill*’ OR ‘developmental’ OR ‘physical’ OR ‘motor’ OR ‘speech’ OR ‘language’ OR ‘communication’ OR ‘neurological’ OR ‘movement’) AND (disorder* OR disabilit* OR deficit* OR dysfunction* OR impairment* OR difficult* OR condition*)) OR ‘disabled persons/’ OR ‘nervous system disease*’ OR ‘spinal cord injur*’ OR ‘disabilit*’ OR ‘non communicative’ OR ‘non verbal’ OR ‘motor skills disorders/’ OR ‘developmental disabilities/’ OR ‘speech language pathology/’ OR ‘speech disorders/’ OR ‘language disorders/’ OR ‘language development disorders/’ OR ‘non verbal communication/’ OR ‘social communication disorders/’ OR ‘movement disorders/’ OR ‘communication disorders/’).

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categories. Studies in the ‘Maybe’ category were discussed in detail to evaluate whether all team members agreed that the eligibility criteria were met.

Data Items

Data items relevant to this review were independently assessed and recorded using The McMaster Quantitative Critical Review Form22 and corresponding guidelines.23

Using the critical review form, a minimum of two researchers reviewed each study. Study characteristics, including partici- pant details, methodological quality, ICF activities, and parti- cipation outcomes, and ICF contextual factors impacting device uptake and success were collected from each study. Study characteristics included the length and frequency of eye gaze assistive technology use, the setting of use (home, school, or clinical setting), study design, and the number of participants (see Table 2). Participant characteristics included the primary health condition, the presence of secondary health condition(s), cognitive function, vision or hearing impairment, and age. Methodological quality was assessed

using Sackett’s Level of Evidence34 and risk of bias (see Table 3). Any single case design studies were further evaluated according to the What Works Clearinghouse (WWC) stan- dards for evaluating single case designs. The main summary of study outcomes mapped to the impacted ICF activities and participation domains, and contextual factors mapped as facil- itators or barriers to eye gaze assistive technology success and uptake can be seen in Table 4.

Syntheses of Results

Often, the studies’ main outcomes were not specifically related to the ICF domain outcomes. In cases where ICF outcomes or factors were not explicitly reported, qualitative statements made by the researchers, practitioners, caregivers, family, or individuals, were mapped to quantitative ‘yes’ or ‘no’ criteria. These statements indicated the presence (yes or no) of ICF activities and participation outcomes and contextual factors. An example that includes the qualitative mapping to the ICF activities and participation outcome of communication is provided; “Although N clearly needed lots of support and

Table 2. Study characteristics (*papers considering the same participants).

# Citation Study description Length and frequency

use Setting Study design Participant info

1a (Borgestig et al., 2016a)13 Study exploring childrens‘ ability to use/control an eye gaze device over time.

20-months use for daily activities

Home & School Single Case Design

n = 9* Aged 5–15 yrs

1b (Borgestig et al., 2017)24 Study exploring how to optimize implementation of eye gaze systems in daily activities

9–10 months of use for daily activities

Home & School Single Case Design

n = 9* Aged 5–15 yrs

2 (Dhas, Samuel, & Manigandan, 2014)25

Assessment/evaluation of computer-access technologies for a child with cerebral palsy through parental perception of difficulty using system.

1 trial, unspecified length of time

Home Case Study n = 1 Age 5

3 (Hornof & Cavender, 2005)26

Study testing two versions of EyeDraw technology on people with and without disabilities (children and adults).

Version 1(local): 1-hr session. Version 1(remote): 7 1-hr sessions Version 2 (local): 1-hr session, some participants completed a second 1-hr session. Version 2 (remote): 3–5 1hr sessions

Lab & Home Single Case Design

n = 3 Aged 9–18 yrs

4 (Karlsson & Wallen, 2017)27

Study exploring parent perceptions of ease of use of two eye-gaze devices by their child and impact of the system on the child’s life.

2 trials of 6 weeks with use for daily activities

Home Multiple Case Study

n = 5 Mean age 4.4 yrs Std dev 1 yr

5 (Man & Wong, 2007)28 Comparison of four different computer access solutions, including an eye gaze system. Assessment of the correlation between movement time and accuracy to the level of comfort and satisfaction.

8 sessions – twice per week, for unspecified length of time

Lab Single Case Design

n = 2 Aged 13–15 yrs

6 (Miyamoto, Shimada, Maki, & Shibasato, 2016)29

Preliminary testing of an eye gaze communication aid.

13 sessions of 20 min each

Lab Case Study n = 2 Age unspecified

7 (Najafi, Friday, & Robertson, 2008)30

Assessment and provision of eye gaze assistive technology for communication.

2 trials of 1 month each for with almost daily sessions of unspecified length

Not specified Case Study n = 1 Age 17

8 (Thoumie et al., 1998)31 Study exploring the usability of an eye gaze communication interface.

1–31 sessions, with an average of 7 sessions for an unspecified length of time

Lab Single Case Design

n = 10 Aged 17–21 yrs

9 (Van Niekerk & Tonsing, 2015)32

Two individuals utilizing eye gaze assistive technology were assessed on their interaction between him/herself and their environment.

3 months of use, 1 case with daily use in the classroom, 1 case without use

Home &/or School

Multiple Case Study

n = 2 Aged 7–9 yrs

10 (Vickers, Istance, & Hyrskykari, 2013)33

Modifying an adapted eye tracking interface to facilitate user navigation through an immersive computer game.

2 sessions of 30 minutes Not specified Single Case Design

n = 12 Aged 8–17 yrs

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was not using the system to initiate communication yet, she had at least started to experience herself as an aided commu- nicator with a voice”.32

For contextual factors, each factor was mapped as either a ‘barrier (−)’ or ‘facilitator (+)’ based on whether the contribution to eye gaze assistive technology success and uptake was negative or positive. In some studies, multiple items were reported under the same category or factor. For example, in the study by Dhas et al. the attitudes of three different parties were reported, two parties had a negative

attitude and one party had a positive attitude.25 This is recorded in Table 4 as ‘Attitudes (−)(−)(+)’. Additionally, some studies explicitly stated contributing factors for indi- vidual participants while others did not. To maintain con- sistency between studies, factors were only considered on a per study basis, meaning that if the same factor was noted for multiple participants it was only recorded once. For example, if three participants in the same study reported technical issues this would be recorded as ‘Products and Technology (−)’.

Table 3. Presence of bias in studies included in the review.

Bias # of studies Studies with bias

Sample or Selection Volunteer/Referral 10 All studies at risk Attention 10 All studies at risk

Measurement or Detection Recall/Memory 7 Studies that implement eye gaze assistive technology for more than one- time use.13,24,26–28,30,32,33

Intervention or Performance Co-Intervention N/A Risk was unable to be determined Timing of Intervention 10 All studies at risk Site of Treatment 7 Any study conducted at home or at school.13,24–27,30,32,33

Table 4. Activities and participation outcomes, environmental factors, and personal factors present in each study.

# Citation Impacted ICF activities and participation subdomains Environmental and personal factors

1a (Borgestig et al., 2016a)13 Communication; Community, Social and Civic Life; General Tasks and Demands; Interpersonal Interactions and Relationships; Learning and Applying Knowledge; Major Life Areas

Attitudes (+); Products and Technology (−); Services, Systems and Policies (+); Support and Relationships (+); Personal Factors (−)(−)

1b (Borgestig et al., 2017)24

2 (Dhas, Samuel, & Manigandan, 2014)25 Communication; Interpersonal Interactions and Relationships; Learning and Applying Knowledge; Major Life Areas

Attitudes (−)(−)(+); Services, Systems, and Policies (+)(+); Personal Factors (−)

3 (Hornof & Cavender, 2005)26 Community, Social and Civic Life Products and Technology (−); Support and Relationships (+); Personal Factors (−)(+)

4 (Karlsson & Wallen, 2017)27 Communication; Community, Social and Civic Life; General Tasks and Demands; Interpersonal Interactions and Relationships; Learning and Applying Knowledge; Major Life Areas

Products and Technology (−)(+); Services, Systems, and Policies (+); Support and Relationships (+); Personal Factors (−)

5 (Man & Wong, 2007)28 Communication; Community, Social and Civic Life; General Tasks and Demands; Interpersonal Interactions and Relationships; Learning and Applying Knowledge; Major Life Areas

Products and Technology (−)

6 (Miyamoto, Shimada, Maki, & Shibasato, 2016)29

Communication; Learning and Applying Knowledge; Major Life Areas

Products and Technology (−); Support and Relationships (+)

7 (Najafi, Friday, & Robertson, 2008)30 Communication; Community, Social and Civic Life; General Tasks and Demands; Interpersonal Interactions and Relationships

Attitudes (+); Products and Technology (−)(+); Services, Systems, and Policies (−)(−) (+); Personal Factors (−)(−)(+)

8 (Thoumie et al., 1998)31 Communication; General Tasks and Demands; Interpersonal Interactions and Relationships;

Attitudes (−); Products and Technology (−); Support and Relationships (−); Personal Factors (−)

9 (Van Niekerk & Tonsing, 2015)32 Communication; Interpersonal Interactions and Relationships; General Tasks and Demands;

Attitudes (−); Products and Technology (−); Services, Systems, and Policies (−)(−) (−)(+); Support and Relationships (+); Personal Factors (+)

10 (Vickers, Istance, & Hyrskykari, 2013)33 Community, Social, and Civil Life Products and Technology (−); Services, Systems, and Policies (−); Personal Factors (−)(+)

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Results

Eleven articles were included in this review. However, two articles by Borgestig et al. each reported on different seg- ments of a larger project, and as such both articles focused on the same participants.13,24 To avoid duplication, these two articles were combined and considered as one study.13,24 As a result, this systematic review includes 11 articles from 10 studies.

In some cases, studies included populations both within and outside the age criteria of 4–21 years. If data could be separated, only information from participants within this age range was considered. This was the case for two studies; a 1-year-old participant in the study by Borgestig et al.13,24

and 20 participants aged 24–53 in the study by Thoumie et al.31 were not considered. In the case of the study by Thoumie et al. some elements of the discussion that related to contextual factors were not assigned to particular partici- pants but were analyzed.31 If the participant data could not be separated, data from all participants were considered. This occurred in only one case in which the participants had a mean age of four years and four months with a standard deviation of one year.27

Study Selection

Combined, all database searches yielded a total of 4980 results with an additional 732 sources identified through hand- searches. After duplicates were removed, 4412 articles were screened. At this stage, 42 articles (about 1%) were sorted into the ‘Maybe’ category. They were discussed in detail, and three researchers voted to determine eligibility. To accept or discard the article, at least two of three reviewers had to agree. For 74% of the articles, all three reviewers agreed, while 26% of the time one reviewer differed in opinion. Of the 4412 undu- plicated results, 4377 articles did not meet the inclusion cri- teria based on their titles and abstracts, leaving 36 full-text articles. After full-text review, 23 articles (approximately 64%) were sorted into the ‘Maybe’ category. These articles were discussed in detail and carefully considered by three research- ers. For 70% of these articles, all three reviewers agreed, while 30% of the time one reviewer differed in opinion. For articles where one reviewer disagreed consensus was typically met after further discussion. A total of 11 articles from 10 studies were considered to meet the inclusion criteria based on the full-text review. The PRISMA flow diagram including reasons for excluding reviewed articles is displayed below (Figure 1).

Figure 1. PRISMA flow diagram.

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Study Characteristics

Detailed study characteristics are provided in Table 2. The studies included a total of 47 participants fitting the eligibility criteria. Sample sizes ranged between 1 and 12 participants. Length and frequency of interventions ranged from one-time use for one hour26 to 20 months of daily use.13 Of the 10 included studies, three reported on eye gaze usage in more than one setting, i.e., home, school, and/or clinical. Five of the studies reported on eye gaze assistive technology use at home, two at school, four in a clinical setting, and two at unspecified locations. Five studies were a single-case design, and five studies were case studies or multiple case studies.

Participant Characteristics

Among the 47 participants, an array of health conditions were observed, cerebralpalsy(n= 26),cervicalmedullarylesions(n =8), muscular dystrophy (n = 8), bilateral infantile striatal necrosis (n = 1), and other unspecified (n = 4). Secondary health conditions and cognitive function were not reported in all studies. However, it was reported that two participants had unknown cognitive function, five had cognitive impairment, four had epilepsy, and four had vision or hearing impairment. The overall average participant age across all studies was 13 years, with a range of 4–21 years. In the case of the participants with muscular dystrophy and cervical medullary lesions, these populations only used the eye gaze assis- tive technology system in a clinical lab environment and no attempt was made to integrate the system into daily activities. The participants with muscular dystrophy still had other commu- nication/computer access options, but an eye gaze assistive tech- nology system may become the only viable option as their condition progresses. In contrast, for most participants with cere- bral palsy, a more comprehensive approach was taken to integrate the eye gaze assistive technology into daily activities.

Methodological Quality

There was significant variability across studies in terms of frequency of data collection and types of outcomes reported. All 10 studies had a Sacket’s Level of Evidence of four which is the second lowest level of evidence.34 This was unsurprising since the population of individuals who use eye tracking assistive technology is very small, and case series studies are common. In addition, biases were present in all studies and are summarized below in Table 3. The type of bias is justified below based on guidelines provided by Law et al.23 The five single case design studies were further evaluated according to WWC standards.35 Design criteria of the studies were assessed to determine if they met the WWC evidence standards. Three studies met evidence standards which indicate that the studies were conducted over a minimum of three different testing sessions, the intervention was systematically manipulated, and the outcomes were sufficiently and reliably measured.13,24,28,31

Two studies did not meet WWC evidence standards.26,33 In the study by Hornof & Cavender, participants were instructed to draw at will using the eye gaze system.26 The study did not control independent variable conditions and participant out- comes were assessed in a subjective manner. The study

conducted by Vickers et al. had only two testing sessions and an insufficient number of data points.33

Volunteer/Referral Bias All studies were at risk for volunteer/referral bias (n = 10). The families and caregivers who volunteer for an eye gaze study are most likely invested in the study due to the often- exhaustive time commitment required to find an access tech- nology for their child. This may impact their attitude toward the technology. Additionally, families who are participating in an eye gaze assistive technology study are likely to have sup- port and relationships that may help facilitate their access to eye gaze assistive technology. Finally, it is likely that families who have access to eye gaze assistive technology would also have access to services, systems, or policies that could enhance performance outcomes and promote technology uptake.

Attention Bias All studies were at risk for attention bias (n = 10). All study participants including parents or caregivers were aware of the study’s purpose. This may have influenced a positive report bias.

Recall/Memory Bias Most studies (n = 7) were at risk for recall/memory bias which included any study that used self-report tools for participants, parents, and caregivers.13,24,26–28,30,32,33 As such, outcomes were reported after the fact, potentially skewing the results.

Co-Intervention Children and youth with severe disabilities that result in signifi- cant communication impairment are often enrolled in various therapy regimens. Within the included studies, there was often little or no mention of therapy involvement co-existing with the eye gaze intervention. Due to the lack of information provided, it was impossible to determine the risk of co-intervention.

Timing of Intervention All studies were at risk of bias due to the timing of the intervention. The interventions ranged from one-time single- use to 20 months of daily-use. Longer timeframes could influence the results due to maturation effects. Shorter studies may not have provided enough time for the child to learn and master the technology.

Site of Treatment Studies that took place at home or school (n = 7) were at risk of bias due to the treatment site.13,24,26,27,29,30,32,33 A comfortable, familiar environment (home or school) may generate results more realistic to what would be seen in daily life, as compared to conducting research at a location unfamiliar to the participant.

Main Summary Measures

The main summary of study outcomes mapped to the impacted ICF activities and participation domains, and con- textual factors mapped as facilitators or barriers to eye gaze assistive technology success and uptake are in Table 4. Each subdomain and contextual factor is discussed in more detail below.

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ICF Activities and Participation Subdomains The number of studies that addressed ICF activities and participation outcomes in each subdomain were found is as follows: communication (n = 8); interpersonal interactions and relationship (n = 7); community, social, and civic life (n = 6); learning and applying knowledge (n = 5); general tasks and demands (n = 6); and major life areas (n = 5). All studies met ICF activities and participation outcomes in at least one category. Three studies met activities and participation out- comes in six categories (1, 4, and 5). The average number of ICF activities and participation subdomains met was 3.7 per study, with a range of 1–6 outcomes per study. Outcomes related to the ICF activities and participation subdomains that were not found in any studies were mobility, self-care, and domestic life.

Communication. According to the ICF, communication out- comes include communicating by language, signs, and sym- bols using communication devices.36 Communication outcomes were found in 8 of the 10 studies.13,24,25,27–32 Six studies reported enhanced communication for the individual.13,24,27,29–32 Two studies reported less direct com- munication outcomes, in which the individual was able to independently use software that could be used to communi- cate through typing.25,28

Community, Social, and Civic Life. The ICF community, social, and civic life subdomain encompasses community life, recreation, and leisure; religion and spirituality; human rights; and political life and citizenship.36 Community, social, and civic life outcomes were found in six studies.13,24,26–28,30,33

All of these studies had outcomes of recreation and leisure including play, relaxation, watching videos, and hobbies. Religion and spirituality, human rights, and political life and citizenship outcomes were not found in any of the 10 studies. However, as the individuals grow and mature there may be opportunities to pursue these interests using eye gaze assistive technology.

General Tasks and Demands. The ICF general tasks and demands subdomain includes undertaking tasks, organizing routines, or handling stress and psychological demands.36

General tasks and demands outcomes were found in six studies.13,24,27,28,30–32 In these studies, individuals employed eye gaze assistive technology to complete communication- related tasks, education-related tasks, or to incorporate these tasks into their daily routines. Furthermore, some individuals were able to communicate their needs through the eye gaze assistive technology which could contribute to their ability to handle stress and psychological demands.

Interpersonal Interactions and Relationships. The ICF inter- personal interactions and relationships subdomain involves the actions and tasks required for basic and complex interactions with people in a contextually and socially appropriate manner.36

Interpersonal interactions and relationships outcomes were found in seven studies.13,24,25,27,28,30–32 In all cases, the action or task performed to meet interpersonal interactions and rela- tionships was communication. The study by Miyamoto et al. is

the only study that met a communication outcome without a co- existing interpersonal interaction and relationships outcome.29

This study focused solely on communication for educational applications and was significantly limited by the constraints of the software used.29

Learning and Applying Knowledge. The ICF learning and applying knowledge subdomain includes purposeful sensory experiences, basic learning, and applying knowledge.36

Learning and applying knowledge outcomes were found in five studies.13,24,25,27–29 Activities that were mapped to these outcomes included communicating with a teacher about edu- cational topics and computer use such as typing, playing educational games, and watching videos.

Major Life Areas. The ICF major life areas subdomain includes outcomes of education, work and employment, and economic life.36 Major life areas outcomes were found in five studies.13,24,25,27–29 Any study that had an outcome related to learning and applying knowledge was also mapped to the major life areas subdomain as access to learning could influ- ence further education, employability, and financial indepen- dence. No direct outcomes of work and employment or economic life were found. However, this review was focused on a child population for whom education is prioritized. If eye gaze assistive technology is embraced, it may open opportu- nities for employment and managing one’s economic life.

ICF Contextual Factors The contextual factors found across the studies included atti- tudes; products and technology; services, systems and policies; support and relationships; and personal factors. In total, 20 environmental and personal factors were noted as facilitators of technology uptake and success, and 29 environmental and personal factors were noted as barriers to technology uptake and success, with an average of 2.0 facilitators (range 0–3) and 2.9 barriers (range 1–5) per study. For every contextual factor, the number of barriers exceeded the number of facilitators with the notable exception of support and relationships, and services, systems, and support.

Attitudes. The ICF environmental factor of ‘attitudes’ classi- fies the attitudes of people external to the person whose situation is being described, such as families, friends, care- givers, health professionals, or societal expectations.36

Attitudes includes thoughts and opinions of the parents, care- giver, or health professionals about the usefulness of the technology, concerns about its implementation, and motiva- tions for participating in the study. These attitudes of people external to the child are usually of significant importance, particularly when considering children with severely limited communication abilities. Three studies had attitudes acting as a facilitator for technology uptake and success.13,24,25,30 In these studies, either the parents gave high satisfaction ratings of the technology or the caregivers and health professionals indicated a positive opinion of the technology. In the study by Borgestig et al. parents reported high satisfaction with eye gaze assistive technology immediately after intervention, how- ever, satisfaction decreased at follow up after withdrawal of

8 E. PERFECT ET AL.

professional services.24 Three studies had attitudes acting as a barrier to technology uptake and success.25,31,32 Van Niekerk et al. reported that the child’s mother “felt disillu- sioned” about the prospect of the device providing adequate support as her child developed literacy skills due to the lim- ited display options on the device screen.32 In the study by Thoumie et al., one individual experienced psychological rejection of the technology because they perceived that the device added to an image of disability.31 Dhas et al. tested various computer access devices, the parents expressed a strong preferences for a hand-held access device (if it was possible) and the child’s teacher expressed concerns about the cost of the device and the potential for damage of the system.25 However, these attitudes conflicted with the opinion of the occupational therapist who recommended the eye gaze assistive technology with a modified headrest. Ultimately, eye gaze assistive technology was not chosen as the computer access method for the child.25

Products and Technology. The ICF ‘products and technology’ environmental factor includes any assistive products and tech- nology adapted or specially designed for improving the func- tioning of a person with a disability.36 Of course, products and technology (i.e., the eye gaze assistive technology system) were present in all studies. In this case, the aim was to capture the negative and positive experiences of the individual relating to the technology. Two studies had products and technology acting as a facilitator for technology uptake and success.27,30

This facilitation was noted as ease of use with the eye gaze application, which is considered to be ease of calibration and starting of the application. Conversely, nine studies reported products and technology acting as a barrier to technology uptake and success.13,24,26–33 These barriers included calibra- tion challenges, insufficient capture field of the eye tracker, and general technical difficulties associated with using the eye gaze assistive technology. The exact cause of technical issues was not always reported; however, in three studies calibration was explicitly noted.31–33 Thoumie et al. reported that the inability to calibrate the system prevented 2/10 youth partici- pants and 6/20 adult participants from using the system.31

Najafi et al. remarked that calibration could be time- consuming and frustrating for the participant and as a result, the participant sometimes used calibration profiles from other people to interact with the system.30 Van Niekerk et al. noted that a participant’s mother and teachers suspected lighting in the environment was interfering with the eye tracker but did not know how to address the issue.32

Services, Systems, and Policies. The ICF ‘services, systems, and policies’ environmental factor encompass all services and bene- fits designed to meet the needs of various sectors of society, in this case, children and youth requiring a technological aid for communication. These may be provided by individuals, associa- tions, organizations, or governments.36 Five studies had services, systems, and policies acting as a facilitator for technology success and uptake.13,24,25,27,30,32 In these cases, there was funding and/ or professional training/support as well as adequate education resources available to the individuals and their families. Three studies discussed services, systems, and policies acting as

a barrier to technology uptake and success.30,32,33 Vickers et al. reported concerns about the feasibility of implementing the eye tracking for recreational purposes in a game environment for individuals without the availability of adequate technical support.33 It is also noteworthy that two of these studies indi- cated positive and negative experiences associated with the avail- able services, systems, and policies.30,32 Both studies reported fundraising concerns and although they had access to a variety of professional resources during the time period of the study (posi- tive experience), there was concern about the availability of long- term support. Particularly in the study by Van Niekerk et al., which took place in South Africa, there were significant chal- lenges associated with access to health professionals, assistive technology, and education resources.32

Support and Relationships

The ICF ‘support and relationships’ environmental factor encompasses all physical and emotional support provided by family, caregivers, and other persons in the daily life of the individual whose situation is being described.36 Although it is evident in all studies that the participants experience signifi- cant physical and emotional support in most aspects of their daily lives, in the context of this review, support is only reported when it specifically relates to the eye gaze assistive technology. Five studies had support and relationships acting as a facilitator for technology success and uptake.13,24,26,27,29,32

In three studies, parents demonstrated a significant commit- ment to the successful implementation of eye tracking assis- tive technology and took an active role in integrating the technology into their child’s daily life.13,24,26,32 In two studies, the eye gaze assistive technology was not used daily but usage was implemented and supported by the children’s teachers.29,32 One study reported support and relationships as a barrier to technology uptake.31 In this case, the amount of support that was necessary to set up the system was not considered to be feasible.31

Personal Factors. Personal factors are not explicitly defined by ICF. In the context of this review, any factor acting as either a facilitator or a barrier to eye gaze assistive technology uptake or success that was not adequately described by environmental factors was classified as a personal factor. The attitude of the person whose situation is being described (in this case the child or youth interacting with the eye tracker) was classified as a personal factor. Four studies indicated that one or more parti- cipants demonstrated a high degree of excitement or motivation when using the eye gaze assistive technology, which is considered to be facilitated device uptake and success.26,30,32,33 Personal fac- tors that were considered barriers to device uptake and success include medical complexities such as epilepsy, comfort issues, and tremors. These factors altered the individual’s position in the capture field or otherwise prevented them from effectively inter- acting with the eye gaze assistive technology. Additional factors include participants tiring or expressing boredom. Seven studies had personal factors acting as a barrier.13,24–27,30,31,33 Sometimes these factors were related, such as a secondary medical condition causing the participant to tire more quickly.

DEVELOPMENTAL NEUROREHABILITATION 9

Discussion

The objectives of this systematic review were to classify eye gaze assistive technology outcomes using the ICF framework, and to identify barriers and facilitators of eye gaze assistive technology success and uptake by children and youth with complex disabilities. Academic literature that analyzes eye gaze assistive technology is limited. Most studies in this emer- ging research area are of poor methodological quality and/or low level of evidence. Consequently, studies of poor metho- dological quality and low level of evidence have been included in this systematic review since they are representative of the best available evidence. Five studies were either case studies or multiple case studies and some studies included only one participant. Furthermore, single case design studies were still analyzed even if their study design did not meet the WWC evidence standards. Due to the limited number of participants and the poor quality of the studies, it is difficult to determine the effectiveness of eye-gaze assistive technology. However, once the results from all the studies were synthesized, six main themes emerged; (i) participants were a heterogeneous group with a variety of needs, (ii) establishing communication is important, (iii) communication enabling other activities and participation domains, (iv) facilitators and barriers affect- ing device uptake and success, (v) recommendations for ser- vice delivery, and (vi) use of the ICF framework in evaluating successful outcomes.

Participants

The results of this systematic review considered participants with four different primary health conditions and five unspe- cified health conditions. Of 47 participants across 10 studies, cerebral palsy was the most prevalent diagnosis, affecting 55% of the participants. For 16 of the 26 participants with cerebral palsy, the eye gaze assistive technology was thoroughly inte- grated into the daily lives of the participants for the duration of the studies.13,24,27,32 It was with these participants that outcomes related to ICF activities and participation were most directly observed, such as attaining a prescribed goal, making a choice, or initiating communication. It was also observed that their support systems made the most significant investments (time and financial) into the success of the eye tracking technology. For seven of the other participants with cerebral palsy, the device was trialed for recreational purposes and thus the literature did not report on the integration of eye gaze assistive technology within daily life.26,33 However, in one study the participants were already experienced in using eye gaze assistive technology.26 The three remaining partici- pants with cerebral palsy trialed a variety of computer access devices and ultimately an eye gaze assistive technology system was not the chosen access method for these individuals.25,28

For two participants in the study by Man & Wong, technical issues caused the eye gaze assistive technology to fail.28 In the study by Dhas et al. comfort issues and preferences of the mother led to a switch solution being chosen for the partici- pant over the eye gaze assistive technology recommended by the occupational therapist.25

The participants with muscular dystrophy and some of the participants with cervical medullary lesions were not necessa- rily reliant on the eye gaze assistive technology as some still maintained other communication options that they found to be easier. For these individuals, eye gaze assistive technologies were not implemented but valuable feedback was provided.

As demonstrated by personal factors observed in this sys- tematic review, it is extremely important to accommodate an individual’s unique needs in the context of their health condi- tion, as well as their environment and personal situation. In only one study, personal factors were observed more frequently as facilitators than as barriers.32 In most studies, the negative experiences of fatigue, discomfort, or boredom were observed more frequently than excitement and motivation. For many participants, feedback was obtained through observation by parents and health professionals, which were recorded as per- sonal factors. One notable exception to this occurred in the study by Hornof & Cavender. Participants were trialing a recreational drawing software called EyeDraw. An 18-year- old female with cerebral palsy was considered to be a “power user” of eye gaze assistive technology and had been using her system for 10 years prior to the study.26 She used her eye gaze assistive technology on two computers simultaneously; she was able to run regular windows applications to chat with friends, write poetry, access the internet, and do school work.26 Using her eye gaze assistive technology, she was able to provide detailed feedback to the study researchers.

Communication

For most participants across all studies, enhancing communi- cation and establishing new language and literacy skills using eye gaze assistive technology were the primary goals. Although communication outcomes were usually the goal for the parti- cipants, they commonly co-occurred with other outcomes including general tasks and demands, interpersonal interac- tions and relationships, learning and applying knowledge, and major life areas. Through communication, individuals can build relationships and connect with one another on a personal level.32 Additionally, an individual who uses eye gaze assistive technology may be able to relay information to their support team to express their needs, aid their care, and improve their autonomy. Furthermore, the ability to commu- nicate may provide opportunities for community involvement as well as education and employment opportunities. Many participants typically communicated through facial expressions and by responding to simple ‘yes’ or ‘no’ questions. Some individuals used a low-tech communication board where the individual points (with their eyes) to a letter, number, or symbol on a board. However, this method relies on a secondary observer to interpret the message relayed by the individual using the communication board. With these meth- ods of communication, it is very difficult for the individual to initiate a conversation and express complex statements and thoughts. Effective utilization of an eye gaze assistive technol- ogy system can drastically reduce the individual’s reliance on caregivers for communication and could allow individuals to relay complex messages and use the internet to communicate.

10 E. PERFECT ET AL.

Communication outcomes using eye gaze assistive technol- ogy were the most prevalent outcomes, found in 8 of the 10 studies included in the review. The two studies that did not have communication outcomes were focused on using eye gaze assistive technology systems recreationally. However, in one study participants were already using eye gaze assistive technology for many daily activities including communication.26Although eight studies achieved communi- cation as an outcome, most participants’ communication skills, including the use of the eye gaze assistive technology, were not sufficiently developed to provide detailed feedback. Additionally, at times, secondary health concerns impacted their ability to interact with the eye gaze assistive technology. As identified by Karlsson et al., the impact of cognitive dis- ability on an individual’s capacity to understand and operate eye gaze assistive technology is not well understood. For individuals with unknown cognitive impairment, there is no clearly defined method of assessment or recommended approach on how to integrate technology into the daily life of the user and their caregivers. This is a critical area for future research.1 Additionally, at least early on, communica- tion using eye gaze assistive technology is achieved by selec- tion of symbols and images rather than by traditional written language.1 Research is needed to establish evidence-based methods for developing communication and literacy skills using eye gaze assistive technology for children with varying levels of cognitive ability.

An individualized approach to generating user feedback and assessing outcomes is required for eye gaze assistive technology. While quantitative measures such as time on task may be used to monitor user skill and progress, they are not necessarily reflective of the utility of the eye gaze system in the context of the daily life of the individual. There was also the emphasis on the attitudes and percep- tions of parents which is indicative of the significant perso- nal commitment required by caregivers to implement eye gaze systems. Notably, in the systematic review by Karlsson et al., one study measured outcomes related to caregiver burden.1 However, it is also essential to understand the individual’s experience when quantifying outcomes. The unique requirements of eye gaze assistive technology users are well suited to using a goal attainment approach to establish and monitor individual outcomes. Generally, goals should be focused on establishing or enhancing com- munication and literacy for the individual and outcome measures should be focused on areas of participation and quality of life.1,15

Communication and Other Activities and Participation Domains

A review on the assessment of AAC interventions by Simeonsson et al. acknowledges the critical importance of provision for intervention, treatment, and education for chil- dren with communication challenges.37 While, Simeonsson et al. recommend the utilization of ICF to monitor progress and promote development of communication skills, the sys- tematic review by Karlsson et al. has stressed the need to

evaluate the impact on the domains of activity and participa- tion by eye gaze assistive technology specifically.1,37

With enhanced communication outcomes, opportunities for outcomes in other areas of activities and participation domains are generated. Seven studies reported the develop- ment of interpersonal interactions and relationships as a result of improved communication skills. Communication is also essential in relaying information related to general tasks and demands (reported in six studies), as well as learn- ing and applying knowledge (reported in five studies). All of these outcomes are critical in educational settings represented by major life areas, which were reported in five studies.

The only activity and participation outcomes that were recorded without the presence of communication-related out- comes were within the community, social and civic life domain. These are important outcomes because it shows that the overall quality of life may be enhanced by the estab- lishment of community connections and hobbies of interest.38

In both studies, this was the only impacted ICF activities and participation domain. Both studies trialed recreational eye gaze software, one for drawing26 and one eye control compu- ter game.33 Although neither software provided communica- tion opportunities for participants, some communication with the individual was required to complete the trials. This com- munication was primarily one way – with the researchers, parents, and caregivers providing direction to participants.

It is essential that communication partners be instructed on how to effectively communicate with the individual who is using eye gaze assistive technology. This will increase social interaction and may reduce the risk of device abandonment.1

Furthermore, multiple communication partners provide more opportunities for both social and educational development and contribute to creating a supportive environment for the individual.1,37

Facilitators and Barriers Towards Device Uptake and Success

A study which assessed the benefits of assistive technologies for activities and participation by Scherer & Glueckauf iden- tified the need for comprehensive assessment and the impor- tance of emphasizing the barriers and facilitators of assistive technology.39 It is evident that when it comes to implement- ing an eye gaze assistive technology system, regardless of the individual’s ability profile, there are more barriers to device uptake and success than there are facilitators. A total of 20 instances of environmental and personal factors acting as facilitators and 29 instances of environmental and personal factors acting as barriers were found in the included studies. Only one study presented more facilitators than barriers, the remaining nine studies either had more barriers than facil- itators or had an equal number of each.

Although many activities and participation outcomes are being met through eye gaze assistive technology, in certain cases, contributing environmental and personal factors led to technology abandonment. For instance, in the study by Najafi et al. although the participant achieved all her goals and the participant, her caregivers, and the assessment team consid- ered the trial a success, the barriers encountered lead to

DEVELOPMENTAL NEUROREHABILITATION 11

rejection of the technology by the participant.30 These barriers were both personal (she found the technology tiring) and environmental (need for funding and concern about access to long-term clinical support).30 Another instance of rejection occurred in the study by Dhas et al. After trialling different computer access methods, the occupational therapist involved in the study recommended use of an eye gaze assistive tech- nology system with a modified headrest but the family’s pre- ference for a hand operated solution, the teacher’s concerns about the device‘s cost, and the potential for damage lead to rejection of the system.25

The most prevalent barriers to device uptake and success were factors related to products and technology as well as personal factors. Almost all studies (n = 9) reported technical issues associated with the eye gaze assistive technology system, primarily calibration issues and sensitivity to head move- ments, and most studies (n = 8) also reported negative aspects of the individual’s experience including fatigue, discomfort, and interference caused by secondary health conditions. Technology issues will most likely lessen or become easier to resolve as eye gaze assistive technology continues to develop; however, these issues will likely never disappear completely. This highlights the importance of both professional and care- giver support associated with using the eye gaze assistive technology system. All family members, teachers, and care- givers who interact regularly with the individual should know how to maintain the device and address common technical issues. They should have access to experienced technical assis- tance if required. As every individual presents a unique and complex ability profile, Personal factors will also likely con- tinue to act as barriers to device uptake and success. These challenges cannot be eliminated, but their impacts can be mitigated. Again, this highlights the necessity of professional support to determine comfortable and compatible seating arrangements as well as to develop customized user interfaces.

Consistent with the results of this review, the services, systems, and policies environmental factor was found to be the most prevalent facilitator of technology success and uptake, with six instances of the positive impact occurring across five studies. These included professional support related to health and education, as well as financial assistance. However, inadequate access to services, systems, and policies was noted as a barrier to device success and uptake in six instances from three studies. All participants involved in these studies had significant access to professional support. However, these levels of support are not necessarily indicative of those that are available to individuals who use eye gaze assistive technology in the community who are not participat- ing in a study.

Recommendations for Service Delivery

A consistent theme presented across articles was the need for more support from health-care providers.30 Borgestig et al. explained the ongoing need to train and support caregivers, whose needs may change as the child develops.24 Involving and supporting families when implementing complex AAC interventions is essential for success.40 In addition, the parent or caregiver should be trained to appropriately react when

issues arise or maintenance updates are needed for the indi- vidual’s system. The information (medical and emotional support) presented to the family/caregivers should be deliv- ered in an appropriate, mindful manner. Furthermore, it is crucial that funds be made available to aid families who may not be able to afford the cost of an eye gaze assistive technol- ogy system on their own. Eye gaze devices are not manufac- tured globally and importing the system is an additional expense and concern for families in certain parts of the world.32

Considering most participants experienced personal factors that presented unique challenges and highlighted specific needs, it would be beneficial to create individualized interven- tion plans using Goal Attainment Scaling.41 By creating indi- vidualized plans specific to each child/youth in collaboration with their support and medical teams, there is an opportunity for enhanced uptake of the eye gaze assistive technology system. By setting goals relative to personal and family expec- tations, outcomes can be more accurately tracked and understood.

Dhas et al. presented goal attainment as a participant learn- ing to type his name using the eye gaze device.25 Borgestig et al. also applied goal attainment scaling methodology to assess goals that individuals set for themselves by utilizing the device at home and/or at school.24 Eye gaze assistive technology can be used to achieve a variety of goals in daily life, as well as for education and recreation, but goals must be suited to the abilities of the individual. Examples can range from simply indicating ‘yes’ or ‘no’ to more advanced applications such as browsing the web and accessing social media.1

Use of the ICF Framework

Through this review, the researchers demonstrated the appli- cation of ICF domain classification for intervention evalua- tion. The aim of utilizing the ICF as a framework is to provide a universal language and conceptual basis for describing and explaining health and health-related states.16 Using the ICF framework has been proposed as a means to assess assistive technology.39 and AAC interventions.37 However, none of the studies included in this systematic review utilized the ICF to measure intervention outcomes which are indicative of the low level of evidence and poor methodological quality of many eye gaze assistive technology studies. The lack of uni- versal language across studies indicates inconsistencies in health and disability descriptions. There is a need for stan- dardization across disciplines and among health-care profes- sionals. The implementation of a common language through the ICF as a standard of practice may improve knowledge transfer across disciplines and aid intervention development and provision. Setting goals that are complementary to the ICF framework have been recommended in the evaluation of AAC interventions.37 Although there are no outcome mea- sures that are specific to eye gaze assistive technology, the recently developed AAC TOMs are aligned with the ICF.15

The outcomes evaluate the areas of impairment, activity, participation, and well-being, both before and after AAC intervention.15 Using Goal Attainment Scaling in conjunction with AAC TOMs would provide the individualized approach

12 E. PERFECT ET AL.

necessary for the diverse population of individuals who use eye gaze assistive technology. In addition, AAC TOMs can allow outcomes to be reported in a standardized format that can be easily interpreted leading to improved comparisons of outcomes among individuals and studies.

Limitations

By conducting a systematic review, researchers are com- monly at risk for database bias, source-selection bias, and publication bias.42 The researchers aimed to identify and consider all articles pertaining to eye gaze assistive technol- ogy for children and youth. Despite the thorough search strategy, there is no guarantee that all relevant articles were captured. This review only includes articles published in English before February 2018. Furthermore, the results of this review were limited by the inclusion criteria. Only children and youth aged 4–21 who do not use functional speech, generate writing, or use any other typical forms of language were considered in this study, although there is evidence of benefits for eye gaze applications in adults, such as for those with Amyotrophic Lateral Sclerosis14,43,44

and for people who are able to communicate with conven- tional methods such as those with spinal cord injury.9 There is also evidence of eye gaze assistive technology being used by infants, as was the case of the excluded 1-year-old parti- cipant in the study by Borgestig et al.13,24 which is further detailed in a case report by Hemmingsson et al.45

Additionally, eye gaze assistive technology use for diagnostic purposes was not included in this review.

Due to the limited number of studies included, the ana- lyzed population may not accurately represent the entirety of all individuals that use eye gaze assistive technology. As well, each study was at risk for at least three forms of bias and had a Sackett’s level of evidence of four. Two of the single case design studies that were further evaluated using WWC criteria did not meet evidence standards. Although this level of evi- dence is expected for this emerging research area, it is the second lowest level, yielding low validity/reliability. Comments and responses from participants as well as par- ent/caregiver perspectives were mapped to the ICF attitudes domain in this review. Although there is some merit to verbal report, this method is vulnerable to bias.46 The primary out- comes of each study were not explicitly mapped to ICF activities and participation domain outcomes by each study’s authors. As the objectives of each paper varied, it is possible that outcomes relevant to this review were not reported. Each researcher may have also had existing bias or opinions influ- encing mapping outcomes. The method of mapping eye gaze outcomes to ICF activities and participation domain out- comes has not been established before in the literature. However, other interventions and outcomes articles have used this mapping method previously.47, 48

Conclusion

Communication skill acquisition is a valuable outcome for children and youth with complex disabilities, as it also

creates opportunities for progress in other life areas. Children and youth have special interaction needs that, if not met, may impede their social, emotional, educational, and creative development, which can further reduce the ability of children with complex disabilities to function in society.26 It is especially important for individuals with disabilities to gain self-determination and continue learning to their greatest extent.48 Eye gaze assistive technology has the ability to enhance performance within many domains related to activities and participation in the daily lives of children and youth with complex disabilities. It was found that eye gaze assistive technology was able to enhance functioning in six of the nine ICF activities and participa- tion domains, with communication outcomes being the most prevalent and co-occurring with all other activities and participation domains outcomes.

Additionally, the population of individuals who use eye gaze assistive technology is diverse and heterogeneous, even amongst individuals with the same primary health condition. Each individual has a unique and often complicated ability profile and consequently, a one size fits all approach to eye gaze assistive technology systems will not work. The initial challenge of assessing the ability of the child to operate an eye tracker is only the first step in a long journey to establish robust communication and education related outcomes. This requires a substantial collaborative effort from health profes- sionals, occupational therapists, teachers, caregivers, and family members.

Despite the benefits of using eye tracking assistive tech- nology, the effects of environmental and personal factors may lead to technology rejection or abandonment. Most notably, products and technology issues and personal fac- tors were found to be barriers to device uptake and success in most studies. The most effective way to mitigate these impacts is through support provided by professionals such as occupational therapists, speech-language pathologists, teachers, and product experts, which proved to be the most prevalent facilitator of device uptake and success. Although professional support is essential for success using eye gaze assistive technology, ongoing commitment, and support of both family members and caregivers is also required. Recommendations for future research include the utilization of goal attainment scaling and AAC TOMs in eye tracking research and the adoption of ICF nomenclature and ideology when presenting disability-related research to promote standardization across disciplines and promote knowledge transfer.

Acknowledgments

Elizabeth Hoskin would like to acknowledge NSERC CGSM. Samantha Noyek and Erin Perfect would like to acknowledge OGS for supporting their Doctoral and Masters research.

Disclosure Statement

The authors declare no conflicts of interest.

DEVELOPMENTAL NEUROREHABILITATION 13

Funding

This work was supported by Natural Sciences and Engineering Research Council of Canada [NSERC CREATE READi]; Natural Sciences and Engineering Research Council of Canada [NSERC RGPIN 2016-04669].

ORCID

Erin Perfect http://orcid.org/0000-0001-9357-8060 Elizabeth Hoskin http://orcid.org/0000-0001-8879-5319 Samantha Noyek http://orcid.org/0000-0002-8379-017X T. Claire Davies http://orcid.org/0000-0003-4880-2654

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