What’s in a name: Dual sensory impairment or deafblindness?

Abstract

Communications about deafblindness within the clinical and research literature are littered with several terms that have not yet been well established or defined, such as deafblindness, dual sensory loss, or combined vision and hearing impairment. Depending on the context (e.g. service delivery for children, adults, or seniors) or the user (e.g. educators, clinicians, researchers, or clients), these terms are sometimes used interchangeably; such practice, however, can be misleading and does not assist the scientific goal of precise communication. The goal of this study was to review the existing definitions of these terms and their use through a systematic review of the literature and by conducting a qualitative survey to solicit the opinions of clinicians and researchers in the field of deafblindness. A systematic review of five databases resulted in 809 references containing terms relevant to deafblindness, which were then searched using the terms, such as deafblind, deaf-blind, deaf AND blind, dual, vision AND hearing, and combined, as they appeared in the titles and/or abstracts. In addition, a survey of researchers and rehabilitation professionals in this domain was conducted. The large majority of articles using deafblind-related terminology were published in clinician-oriented journals, whereas authors of high-impact research journal articles (many outside the domain of sensory rehabilitation) were more likely to utilize terms such as dual sensory or combined impairment. This segregation was similar in the 68 responses obtained through the survey. There is a need to harmonize the interpretation of terminology, specifically across professionals and interest groups relevant to deafblindness. Through the development of comparable terminology and clarity in communication, rehabilitation professionals will find it easier to access (and translate) research findings in their respective fields. In addition, the exchange of ideas between practitioners and researchers will be easier, resulting in more practically relevant research projects.

Keywords

Deafblindness dual sensory impairment knowledge transfer rehabilitation terminology

The terminologies used in the domain of sensory impairment have evolved in recent decades. Until the 1950s, vision rehabilitation predominantly used the term blindness with reference to any level of visual loss (Goodrich, Arditi, Rubin, Keeffe, & Legge, 2008). In 1955, the term low vision was first used in a research publication to describe individuals with residual functional vision (Hellinger & Green, 1955). Similarly, in the domain of hearing loss, the terms deaf and hard-of-hearing coexist in both research and practice in order to differentiate severity levels of hearing loss. In the case of Deaf with a capital D, additional cultural information is conveyed, describing persons who are part of the Deaf community (Higgins, 1980). The investigation of combined vision and hearing loss, generally referred to as deafblindness, has recently gained momentum, in large part due to the increasing number of older adults who have concurrent age-related sensory impairments (Schneider et al., 2011). The perception of the meaning of the term and terminology used in this domain have been shaped by individuals such as Helen Keller and by clients with more common conditions, such as Usher syndrome.

In rehabilitation service delivery, the definition of deafblindness includes individuals with any level of concurrent vision and hearing impairment, independent of time or order of onset or of severity. Some agencies use the term dual sensory impairment to explain the spectrum of deafblindness, while others include functional domains that are affected by the impairment, such as communication, information access, socialization, mobility, and activities of daily living. In addition, it is often mentioned that deafblindness is not simply the addition of vision and hearing impairments but creates a unique entity (Australian Deafblind Council, 2012; Canadian Deafblind Association, 2012; Deafblind International, 2012; Helen Keller National Center, 2012; SENSE, 2012; The American Association of the Deafblind, 2012).

The unified term deafblindness has replaced the hyphenated term deaf-blindness in order to reflect the unique needs of persons who cannot compensate for the loss of one sense with the other (Lagati, 1995). The distinctiveness and rights of persons who are deafblind are reflected in the recognition given by the European Parliament (2004). Communications about deafblindness contain several terms that have not been well defined, such as deafblindness, dual sensory loss, or combined vision and hearing impairment. Depending on the context (e.g. service delivery for children, adults, or seniors) or the user (e.g. educators, clinicians, researchers, or clients), these terms are sometimes used interchangeably; this practice, however, can be misleading and does not assist the scientific need for precise communication. A recent publication specifically called for an operational definition to be developed and promoted for use by all stakeholders (Schneider et al., 2011). The goal of this study was to review the existing definitions of these terms through a systematic literature review and to conduct a survey of rehabilitation service providers and researchers. Given the growing emphasis on knowledge transfer between knowledge producers (e.g. researchers) and knowledge users (e.g. service providers or policy makers), harmonizing the interpretation of these terms should greatly enhance the exchange of relevant information (Graham et al., 2006).

Method — systematic literature review

During the systematic review (summer of 2011), no beginning cut off date or language restrictions were used, and the last search date was 1 August of that year. Search strategies were developed for the Cochrane Database of Systematic Reviews, MEDLINE, Embase, AMED, Web of Science, and CINAHL, supplemented by a hand search of New Outlook for the Blind, Journal of Visual Impairment and Blindness, Re:View, and Insight: Research and Practice in Visual Impairment and Blindness. These journals were selected due to their publication record and relevance to the field of deafblindness rehabilitation (an example of the search string for Medline is provided in Appendix). The resulting 809 references were entered into Endnote, generating a word document with full references of all entries. This file was uploaded into ATLAS.ti for text-based analysis and searched using the terms, such as deafblind, deaf-blind, deaf AND blind, dual, vision AND hearing, and combined, as they appeared in the titles and/or abstracts.

Method — survey

After the approval by the Ethics Review Board of the Centre de recherche interdisciplinaire en réadaptation (CRIR) du Montréal métropolitain, data acquisition for the survey was conducted in four phases. First, the survey was included in the 200 registration packages of the Premier colloque francophone international sur la surdicécité (First Francophone International Colloquium on Deafblindness), held in Quebec City, Quebec, Canada, in May 2011. Second, the survey was distributed in June 2011 via e-mail to all professionals involved in dual and multiple impairment rehabilitation in the Montreal region through its three rehabilitation agencies. Third, 139 agencies that offer rehabilitation services for individuals with deafblindness were identified via a Google search worldwide, and the survey was sent to the e-mail contact person identified on their websites. Finally, the survey link and accessible Word document were made available on the website of Deafblind International, a worldwide association promoting services for deafblind people. The survey (available in English, French, German, Spanish, Portuguese, and Italian) included demographic items as well as five open-ended questions soliciting participant perspectives regarding research and rehabilitation priorities and their use of terminology in dual sensory impairment. The first two questions, analyzed here, asked participants how they define both deafblindness and dual sensory impairment from a functional perspective. Prior to the start of data analysis, two of the authors (W.W. and K.S.) had a candid discussion concerning each of their own preconceived ideas, attitudes, and perceptions toward the research topic in order to document them and not to allow them to enter into the analysis process. This is called reflexivity (Barry, Britten, Barber, Bradley, & Stevenson, 1999). By documenting personal biases before analysis, potential conflicts in interpretation can be monitored, recognized, and potentially avoided during collaboration. In case of discrepancy on interpretation, conflicts were resolved through face-to-face discussion (Hall, Long, Bermbach, Jordan, & Patterson, 2005). All survey responses were translated into English by the authors of this article and then analyzed using content analysis (Elo & Kyngas, 2008) through open coding, creating categories, and abstraction. Coding was conducted face to face (by K.S. and W.W.), reading line by line through transcripts, and assigning codes through mutual agreement. Meaningful patterns within and across question responses were identified and coded. Coded passages were grouped or categorized. Finally, representative excerpts across participant responses were selected based on repeating themes. Data analyses continued until extending analyses produced no new information (Morse & Field, 1995).

Results — systematic literature review

The terminologies found in the obtained references were deaf-blind (n = 310), deafblind (n = 81), deaf AND blind/vision impairment (n = 59), deaf/blind (n = 9), as well as a series of terms that separately stated visual and hearing status, such as dual sensory impairment (n = 140), combined impairment (n = 20), or disturbances of/deficiencies of/compromised vision and hearing (n = 4). The trend to utilize identifiers such as dual sensory or combined impairment emerged during the 1990s. The large majority of articles using deafblind-related terminology were published in journals generally intended for professionals who provide rehabilitation services, such as The Journal of Visual Impairment and Blindness or American Annals of the Deaf. The terms dual sensory or combined impairment of vision and hearing were used in journals that (1) have higher impact factors (e.g. International Journal of Geriatric Psychiatry, Developmental Neurobiology, and Behavior Therapy) or (2) cater to researchers outside the domain of vision and hearing (e.g. Neurorehabilitation, Gerontologist, Clinical Nursing Research, or European Archives of Oto-Rhino-Laryngology).

Findings — survey

Given the four different data acquisition waves, it is not possible to calculate an exact response rate; however, at the Premier colloque francophone international sur la surdicécité, 200 surveys were distributed, of which 26 were completed (13%). This value is low compared to previous reports on survey participation (Van Horn, Green, & Martinussen, 2009); however, the nature of the survey required prospective participants to take the time to reflect and provide responses to open-set questions rather than close-set questions, thereby possibly deterring some from participation.

Sixty-eight participants from six countries (Canada: 35, Australia: 2, France: 8, Romania: 1, United Kingdom: 5, United States: 16, and unknown: 1) completed the survey. The 15 men and 52 women (1 incomplete answer) ranged in age from 24 to 65 years (M = 46 years, SD = 12 years). Their educational level included high school (3), college (4), certificate (1), diploma (8), bachelor’s degree (10), master’s degree (30), MD PhD (1), doctorate in optometry (1), or PhD (10). Their current professions included academic research (4), advocacy (2), audiology (4), Deafblind service coordination (4), senior management (2), management (7), education (10), orientation and mobility (7), ophthalmology (1), optometry (1), occupational therapy (3), psychology (3), retirement (2), social work (4), speech and language pathology (8), low vision rehabilitation (5), whereby some professionals work in more than one area. Of the respondents, one indicated to be visually impaired, one reported having a hearing loss, and five as having a combined vision and hearing impairment.

Question 1. “What is your functional definition of deafblindness?” whereby functional was defined “with regard to the activities and habits of the person”. Analyses gave rise to five components of a definition, which were (1) domains where functional limitations became apparent, (2) time and order of impairment onset, (3) severity and the multiplicatory effects of the impairment, (4) impairment-specific services, and (5) vocabulary that ties these four components together. The respondents’ definition of deafblindness references the following functional domains: communication, mobility, information access, activities of daily living, employment, leisure, education/literacy, participation, safety/security, family, isolation, independence and life satisfaction. Also, the concept of time was utilized, whereby the definition of deafblindness included references to time of onset (congenital or early in life) and order of onset (simultaneous or hearing loss before vision loss). The third aspect component addressed issues related to the severity of the impairments and their multiplicatory effect: “Someone who is very afflicted on two aspects—severely impaired auditorily and visually, deaf with blind gestural communication, or using tactile sign language”. Participants indicated that deafblindness, in general, is a more severe impairment, hearing loss is more profound than vision loss, and the individuals cannot utilize one sense to compensate for the other. The fourth component was reference to the use of deafblind-specific services (tactile sign language and interveners).

Question 2. “What is your functional definition of dual sensory impairment (hearing/vision)?” Of the 68 respondents, 25 considered deafblindness and dual sensory impairment synonymous: “I don’t distinguish deafblindness and dual sensory impairment. I use the expression dual sensory impairment to explain the word deafblindness when I see that my listener does not understand what I mean by deafblindness”. Of these, 11 had a preference for deafblindness in their professional environment, 6 preferred dual sensory impairment, while 3 proposed an altogether different terminology (rehabilitation, continued learning, and combined vision and hearing loss). When compared to the terminology used in Question 1, only two components showed differences. First, when referring to time of onset, dual sensory impairment was defined as late-onset, often adult or age related: “The dual sensory impairment is present when an individual who has lived with one disability for a big part of his life develops the second impairment while aging,” “. . . someone who grew up without any impairment that could impede his development. For example, someone with macular degeneration and presbycusis”, or “I also often think of persons who are older when they acquire their losses as falling into this definition”. Second, the definition was characterized by less severe loss in each sensory modality: “Two impairments at lower degrees than deafblindness. Making it possible to compensate the loss of one with the other” or “. . . considered to have combined hearing loss in the mild to severe categories and not to be legally blind but have vision loss that impacts on activities of daily living and independence”.

Discussion

The purpose of this study was to examine the existing terminology and its use related to combined vision and hearing loss in both the research community and among professionals working in the field of rehabilitation. One key finding from both the literature review and the survey responses was that individuals who reported to be primarily engaged in service delivery or clinical activities (n = 56) differed in their use and interpretation of the term deafblindness when compared to persons identifying themselves more as researchers (n = 12). Service providers cited the definition proposed by the agencies for which they work, with the term deafblind being accepted as the all-encompassing terminology describing all levels of severity, independent of time or order of onset or age of the client. Researchers, however, preferred terminology, such as dual sensory impairment, that allows for more subtle distinctions along the spectrum of impairment. Interestingly, the qualifier dual creates ambiguity simply because it is not stated which two senses are impaired. This may be the reason why some authors have chosen the term combined vision and hearing loss, which, in our opinion, is better suited to describe the spectrum of vision and hearing impairment on which blindness and deafness are simply two extremes. This strikes us as particularly useful when communicating with clients, the public, or professionals from other domains, whose perception of the meaning of the term deafblindness is often strongly influenced by a lack of awareness of the severity spectrum and may lead to misunderstandings.

The systematic review revealed the great variety of journals that publish research on combined vision and hearing loss. A substantial number of research publications were found in journals focusing on pediatrics, aging, genetics, population health, nursing, medicine, neuroscience, education, or psychology, among others. This variety underscores the importance of research into the needs and characteristics of this population, but it also highlights the need for compatible use of terminology across disciplines. Specifically, researchers in areas not based in sensory loss may be influenced by their own perception of terms such as deaf or blind and, therefore, may shy away from their use.

In order to promote research into combined vision and hearing loss, a unified approach to terminology would be very useful. It would improve access to published materials through search terms that are shared by service providers and researchers, within and outside the field. At present, this is a challenge, as both sides may be unaware of their discrepancy in language use or they may prefer the traditional use of deafblind as an umbrella term. Our analyses suggest that the terms deafblindness and dual sensory impairment could serve this function in combination, whereby deafblindness, in the tradition of rehabilitation service delivery, would describe more severe impairments in both senses, specifically in the pediatric population and adults with “early”-onset (e.g. Usher syndrome). Meanwhile, dual sensory impairment, in the tradition of the research community, could become the term of choice in the domain of age-related conditions, such as age-related macular degeneration and presbycusis, the most common combination of impairments in older adults (Wittich, Watanabe, & Gagne, 2012). This division of terms would also reflect the differences reported by the respondents who chose to distinguish between the two terms based on severity and time of onset. Furthermore, these already co-existing terms would provide a choice for clients as to how they prefer to identify themselves, as one participant stated: “Labeling can be a sensitive subject, personally, I feel that it is whatever the individual feels comfortable with.”

Limitations

Language itself posed a challenge within this study. Even though the survey was made available in six languages, the 68 responses were all provided in either French or English. For the purpose of the analysis, the French terms surdicécité and sourd-aveugle were translated as deafblindness and deaf-blind, respectively. It has been pointed out that terminology across languages differs; however, since the international language for publication is currently English, the results of this study inform authors of other languages about the use of the relevant English terminologies (Lagati, 1995). Given the large proportion of respondents from North America, it is possible that a bias exists, reflecting the opinions of service providers and researchers within the United States and Canada. Before international consensus about terminology may be possible, it would be advisable to raise this issue in a forum where more stakeholders will be able to contribute to this discussion. Such a discussion should also include a range of persons with combined vision and hearing loss, in order to incorporate the perspective of those individuals who live the experience themselves. Their perspective would greatly enhance our mutual understanding of the personal impact of terminology in rehabilitation and would warrant an investigation on its own.

A further limitation of the present data is that several stakeholders in the domain of combined sensory loss are not represented. The survey was targeted at individuals involved in the rehabilitation field; however, numerous professionals in education provide essential services, specifically when dealing with the pediatric clientele. In addition, policy makers and funding agencies may have terminologies that differ from the service provision and research domains. These groups also differ in their way of communication, as many relevant policy or education documents on dual impairment are not published in peer-reviewed journals and are, therefore, not included in the present review. These often web-based sources require separate search strategies and are not always familiar or known to professionals from other fields.

In order to reflect the true complexity of terminology in combined vision and hearing loss, an analysis of the context in which terms are used will also be required. The presented quantitative analysis of terminology frequency ignores who uses which term when and with what implied meaning. Such an approach would elucidate specific details about differences in terminology use across the stakeholder groups, the severity of each impairment, the time and order of onset, and the age of the client. This analysis would also provide more detailed information about the change in use of terms over time across domains, and whether such change would reflect important developments in research, policy, and service delivery.

Conclusion

This study aims to open a dialogue among researchers and professionals who provide clinical, education, and/or rehabilitation services in the domain of combined vision and hearing loss in order to facilitate improved exchange of ideas through the harmonized use of terminology. At present, knowledge transfer potentially encounters barriers in communication simply because the term deafblindness means different things to different people. The findings of this study serve to offer information to service providers about the terminologies applied in research settings, while clarifying for researchers how rehabilitation professionals may interpret clinical terminology. Future research in this domain could examine whether communication styles and terminologies in other countries, languages, or among other stakeholders encounters similar discrepancies.

Footnotes

Appendix

Acknowledgements

We would like to thank Martine Gendron and the Institut Raymond-Dewar for their assistance with translations and technical support during the survey administration.

Funding

This research was supported by a post-doctoral fellowship to W. Wittich from the Canadian Institutes of Health Research, MFE - 104424.

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