Impact of visual impairment on the lives of young adults in the Netherlands: a concept-mapping approach.

Abstract Purpose: While the impact of visual impairments on specific aspects of young adults’ lives is well recognised, a systematic understanding of its impact on all life aspects is lacking. This study aims to provide an overview of life aspects affected by visual impairment in young adults (aged 18–25 years) using a concept-mapping approach. Method: Visually impaired young adults (n = 22) and rehabilitation professionals (n = 16) participated in online concept-mapping workshops (brainstorm procedure), to explore how having a visual impairment influences the lives of young adults. Statements were categorised based on similarity and importance. Using multidimensional scaling, concept maps were produced and interpreted. Results: A total of 59 and 260 statements were generated by young adults and professionals, respectively, resulting in 99 individual statements after checking and deduplication. The combined concept map revealed 11 clusters: work, study, information and regulations, social skills, living independently, computer, social relationships, sport and activities, mobility, leisure time, and hobby. Conclusions: The concept maps provided useful insight into activities influenced by visual impairments in young adults, which can be used by rehabilitation centres to improve their services. This might help in goal setting, rehabilitation referral and successful transition to adult life, ultimately increasing participation and quality of life. Implications for rehabilitation Having a visual impairment affects various life-aspects related to participation, including activities related to work, study, social skills and relationships, activities of daily living, leisure time and mobility. Concept-mapping helped to identify the life aspects affected by low vision, and quantify these aspects in terms of importance according to young adults and low vision rehabilitation professionals. Low vision rehabilitation centres should focus on all life aspects found in this study when identifying the needs of young adults, as this might aid goal setting and rehabilitation referral, ultimately leading to more successful transitions, better participation and quality of life.


Introduction
Visual impairment occurs mainly in older age and, in 2010, affecting over 200 million people worldwide. However, the estimates of visually impaired people aged 14-49 years (i.e. >80 million) cannot be denied. [1] In the Netherlands, it is estimated that in 2009 $ 17,800 persons aged 14-49 years had low vision. [2] However, both global and national data on the prevalence of visual impairment in the youngest adults (e.g. 18-25 years) are lacking. In young adults, the transition to adulthood is often accompanied by various challenges, [3] especially when dealing with disabilities. [4] Young adults face important changes related to study, work and housing. [5][6][7][8] Dealing with a disability during changes in important life transitions might result in psychological distress [9] and interfere with developmental tasks. [10] This may lead to a less successful transition to adulthood, which can influence the physical, social and psychological potential of young adults, and their full participation in adult life. [11] Therefore, having a visual impairment might present a risk to young adults for reduced participation and social exclusion. Moreover, young adults with low vision experience more difficulties in social interaction, and initiating and sustaining (romantic) relationships. [12][13][14] Similar to others with a disability, visually impaired young adults have fewer friends and are more likely to feel lonely than young adults without disabilities. [3,[15][16][17] Furthermore, visually impaired young adults less often have a (paid) job compared to young adults without visual disabilities. [18,19] However, there is no gap in educational dropout and graduation rates to explain this difference, [19,20] although external factors such as negative attitudes of employers and inaccessible work environments have also shown to be a major barrier to employment. [21,22] With regard to participation, young adults most frequently face challenges related to mobility, domestic life, communication, interpersonal interaction and relationships, general tasks and demands, major life areas, and leisure activities. [23,24] However, previous studies focused only on the impact of visual impairment on particular life aspects, such as social relations, intimate relations, study or work. With the exception of the investigation by Van Leeuwen et al. (2015), to our knowledge no study has focused on the impact of a visual impairment on the life of young adults as a whole. However, the study of Van Leeuwen et al. was a patient record study, and did not focus on the impact of a visual impairment on the life of young adults according to important stakeholders, i.e. young adults and professionals working with them. [24] Qualitative research methods are commonly used to explore the context of health-related outcomes. [25][26][27][28][29] For example in-depth interviews and focus group discussions have received much attention in health-related research. However, a variety of other participatory research methods exists. Conceptmapping is one of these methods, [30][31][32] and it provides a way to quantify qualitative data to discover differences and similarities between stakeholders' ideas. [33] Concept-mapping is a structured, multi-step method which yields a conceptual framework about the stakeholder's thoughts on the topic at hand and visualises how these thoughts are connected. [31] Concept-mapping has been used for various purposes in health research, such as programme planning and programme evaluation, [31,[34][35][36] exploring risk factors and experiences, [37][38][39][40][41] generating hypothesis and developing theory, [33] developing measurement instruments, [30,[42][43][44] and discovering critical issues in programme implementation. [45] Furthermore, it has been used to gain insight in a variety of social and health contexts, including experiences with intimate partner violence, [35] burden of low back and neck pain, [30,42] barriers and facilitators for breast cancer screening, [33,37] and quality of radiation care. [41] Moreover, conceptmapping has also been used to describe the impact of a visual impairment on the participation of children. [46] Since concept-mapping is a useful tool to clarify complex, diffuse and unclear concepts, such as participation, this study aims to elucidate which life aspects are affected by visual impairment in young adults aged 18-25 years using a concept mapping approach. The focus of this article is on young adults' participation in activities, and participation needs and restrictions experienced by them.

Study participants
Invited to participate were young adults aged 18-25 years with a visual impairment and professionals specialised in working with visually impaired young adults. All young adults with a visual impairment were clients of two Dutch nationwide rehabilitation organisations, Royal Dutch Visio and Bartim eus. Young adults were approached by mail and/or email; the written information was provided using a clear and large font with extra spacing. A (digital) informed consent form was attached to the information letter. Young adults had the possibility to contact the researchers by telephone and email, which was mentioned in the letter. When informed consent was given, young adults received a phone call in which information was provided and procedures were explained. Participating young adults were selected consecutively on a voluntary basis. Young adults needed to have access to a computer, laptop, tablet or smartphone in order to participate. This could either be a private or public device, for example as seen in schools or libraries. Young adults were free to ask for assistance from acquaintances when participating in the study, and had the option to ask for guidance from one of the researchers. Professionals were employees of the two rehabilitation organisations who often worked with young adults, such as educational counsellors, vocational counsellors, mobility trainers and occupational therapists, psychologists or social workers. The contact persons of these organisations were asked to select representative professionals from various backgrounds, since most professionals tend to focus on their own areas of expertise. [24,47] This study was approved as an amendment to the study for the development of a questionnaire for children aged 18 years, the PAI-CY (children and youth), by the Medical Ethics Committee of the VU University Medical Center in Amsterdam and adhered to the tenets of the Declaration of Helsinki. All participants gave their written informed consent before the start of the study.

Concept-mapping procedure
Concept-mapping consists of five steps which are both qualitative and quantitative. In the first step, the brainstorm session, a seeding statement is used to generate statements. In this study, the following seeding statement was used: "Thinking as broadly as possible, generate statements about activities that young adults with a visual impairment would (independently) like to participate in." The seeding statement was not limited to those activities influenced by a visual impairment, in order to generate a broad overview of statements and activities young adults with a visual impairment would like to participate in. Participating young adults received an email with the link to an online questionnaire which included the seeding statement together with questions about demographic variables. The email again included information on the procedure, and the contact information of the researchers was mentioned in case young adults required further information or guidance. The online questionnaire was compatible with most assistive software for visually impaired persons (e.g. enlargement programmes or text-to-speech programmes), although no specific adaptations to the online questionnaire programme were made to make it accessible with all assistive software available. However, the layout of the questionnaire was made user-friendly for people with a visual impairment by using a clear and large font. Young adults were stimulated to fill in the questionnaire by offering them the chance to win a gift card. Professionals received an email with the seeding statement and could reply their statements by email. All generated statements were checked, deduplicated and reported back to the participants through an online concept-mapping software programme (Concept Systems Inc., Ithaca, NY). To login to this software, participants received instructions by email, including a personal username and password. Because the concept-mapping software is internet-based, it is accessible with most assistive software programmes, for example enlargement programmes. However, it was not possible to make specific adaptations to the software to make it more user-friendly for young adults with a visual impairment, although young adults again were free to ask for help from acquaintances or ask one of the researchers for guidance. They were then offered guidance via telephone or a home-visit. However, none of the young adults made use of these options. Young adults were stimulated to complete the concept-mapping procedure by offering them another incentive. Participants sorted the generated statements in the second step and rated them in the third step. For the sorting procedure, participants created themes and assigned a name to each theme. Then, they sorted the statements within the themes. In step 3, participants were asked to rate the importance of the generated statements on a scale from 0-10. In step 4, a concept map was computed by the software programme based on the obtained data.

Concept-mapping analysis
To analyse patterns among the generated, sorted and rated statements, the software programme uses three steps in the core analysis. First, the software creates a similarity matrix based on the sort data, which displays the number of participants who sorted each pair of statements together in themes. Next, the software uses multidimensional scaling of the similarity matrix, to locate each statement as a separate point on a map. Last, hierarchical cluster analysis of the multidimensional scaling coordinates divides the statements on the map into groups. [48] The result is a two-dimensional visual map grouping statements into a given number of clusters, illustrating content similarities and cluster priority. Items located close to one another form a cluster. The distance between the clusters and statements represents the similarity; the smaller the distance between clusters and statements, the more they are conceptually alike. The rating of statements is represented in the thickness of clusters; thicker clusters are more important than thinner clusters. Based on the names assigned to each theme by participants, the software chooses a name for each cluster, and gives suggestions for other names. In the final step, the concept map is interpreted and the number of clusters is revised, resulting in a concept map with a cluster number which best fits the data. The final stress of the concept map is calculated to see the statistical fit to the multidimensional scaling model. Lower stress values represent better statistical fit. Furthermore, intra-class correlation coefficients (ICC) were calculated to explore the reliability in statement rating in young adults and professionals, using a two-way random model. Additionally, rating data were imported in SPSS version 22.0 (SPSS Inc., Chicago, IL) to identify any differences in statement rating between young adults and professionals. This was done using independent samples t-tests and Pearson correlations. In this study, one concept map was developed based on the sorting and rating data of young adults and another was developed based on the sorting and rating data of professionals. Additionally, a third concept map was developed that combined the sorting and rating data of both young adults and professionals.

Response and characteristics
A total of 22 young adults (41% male) responded to the invitation and filled in the online questionnaire (response rate 12%). Most young adults attended regular primary and secondary education, whereas three attended special primary education and six attended special secondary education. Twelve participants completed secondary education and nine participants completed higher education or university. One participant only completed primary education. Most young adults did not have a (part-time) job (59%).
Of the 16 professionals, 15 (73% female) replied to the email (response rate 94%) and generated statements. Their professional backgrounds were varied: social workers, (educational) ambulatory counsellors, educational or vocational managers and advisors, behavioural scientists (e.g. child psychologist) and occupational therapists.
Young adults generated a total of 59 statements in response to the seeding statement whereas professionals generated 260 statements. All statements were checked and deduplicated, resulting in 99 individual statements generated by young adults and professionals (Table 1).
In total, 26 young adults were invited to sort and rate the statements using the concept-mapping software. The sorting procedure was completed by seven young adults (27%), while nine young adults (35%) completed the rating procedure. Of the 16 professionals that were invited to sort and rate the statements, 12 (75%) completed the sorting procedure and 13 (81%) the rating procedure.

Concept-mapping results young adults
Data from the concept-mapping procedure for young adults yielded a graphical presentation of all activities that young adults with a visual impairment would like to participate in (independently), and their interrelationships. The final stress of the map was 0.30, indicating sufficient statistical fit to the multidimensional scaling model. A 10-cluster map was chosen, as this resulted in the best interpretation of clusters (Figure 1(a)). The high density of the dots within the clusters self-care, mobility, social network, going out, study and work, indicate high agreement in similarity between statements. However, dots in other clusters were less dense, indicating that these statements were more difficult to classify and less similar to other statements in the same cluster. The cluster numbers reflect the mean rating scores, with cluster 1 (study) being the most important. The statements within this cluster had a mean rating of 8.1 out of 10. Other clusters which were considered very important were fairs, workshop and information meetings, work, and going out. Digital/online and visual aids, explaining, and household were the least important clusters, as indicated by their cluster numbers. The ICC showed a moderate degree of reliability in the rating of young adults, with an average measure of 0.67 (p < 0.001).

Concept-mapping results professionals
Data analysis of the professionals resulted in a concept map with nine clusters which represented best fit of the data, and displays what activities young adults with a visual impairment would like to participate in (independently) (Figure 1(b)). The final stress of the map was 0.20, indicating good statistical fit to the multidimensional scaling model. The high density of the dots indicates high agreement in similarity between statements in the clusters mobility, practical skills, study, social network, and work. Within the clusters related to computer, leisure time and peer contact, the dots were more scattered, indicating less agreement in similarity. Statements in the cluster work were regarded as most important by professionals; computer and study were also rated as very important. Statements in the cluster hobbies/sport/leisure time were considered the least important. The mean rating of statements in this cluster was 7.3 out of 10. Professionals had a high degree of reliability in their ratings, as indicated by the ICC average measure of 0.83 (p < 0.001).

Differences and similarities in concept maps
In the concept map of professionals the cluster names mobility, social network, study and work were similar to those in the concept map of young adults. However, within these clusters, professionals and young adults sorted the statements differently (Table 1). Both young adults and professionals indicated that the clusters relating to work and study were the most important. The statements knowing how to tell employers about visual Going to a terrace impairment, following a study independently, starting and maintaining a relationship with a partner, living independently and arriving at school/university independently are rated as very important by professionals (rating at least 9.0), whereas young adults rated the statement being equal to people without a visual impairment as very important. Both young adults and professionals rated the statements finishing a study successfully, carrying out my work decently and finding a job where appreciated as very important. Young adults rated the statements knowing what is expected when having a relationship, putting on make-up, knowing which recipes are appropriate, knowing about sexuality and intimacy, knowing whether to drive a scooter, following the latest fashion trends and gaming independently as rather unimportant (rating below 6.0). There was moderate to strong correlation between professionals and young adults in the rating of statements (r ¼ 0.6, p < 0.001). The difference in the rating of statements between young adults and professionals was on average À0.57, indicating that young adults rated the statements as being somewhat less important. Despite the small average difference, 29 statements (29%) were rated by young adults as being rather less important compared with ratings by professionals (rating difference 1.0 or more) ( Table 1, indicated with d). These statements were mostly found in the clusters of the combined concept map social skills, living independently, social/relationships and hobby. On the other hand, three statements (3%) were rated by young adults as being rather more important compared with ratings by professionals (Table 1, indicated with e). These statements concerned listening or making music, finding the way to an unknown location and travelling internationally. Independent samples t-tests showed that five statements differed significantly in importance between professionals and young adults (p < 0.05) ( Table 1, indicated with f). These statements concerned knowing what to expect when having a relationship, finding appropriate software for computer and telephone, knowing about sexuality and intimacy, knowing whether to drive a scooter and following the latest fashion trends. The differences in rating were also apparent when comparing the concept maps of young adults and professionals. The mean ratings of professionals ranged from 7.3 for hobbies/sport/leisure time to 8.7 for work. In comparison, the mean ratings of young adults ranged from 5.7 for household to 8.1 for study. Thus, young adults considered some of the statements to be less important than professionals. Table 1 presents a list of all 99 generated statements regarding activities included in the concept-mapping procedure, together with the clusters to which they were assigned by participants and their mean rating scores.

Combined concept map
When data of professionals and young adults were combined and a new concept-mapping analysis was performed, a combined concept map of 11 clusters was considered best (Figure 1(c)). The final stress of the map was 0.21, indicating good statistical fit to the multidimensional scaling model. Although some cluster names corresponded with those in the concept maps of both young adults and professionals (such as mobility, study and work), statements in these clusters did not always correspond with statements in the concept map of both young adults or professionals. The high density of the dots in the clusters study, living independently, mobility and social skills indicate high agreement in the similarity of statements in these clusters. Less agreement in similarity was shown in other clusters, especially related to having a hobby. The cluster numbers reflect the mean rating scores of young adults and professionals, with cluster 1 being the most important (work; mean score 8.6) and cluster 11 the least important (hobby; mean score 6.8). There was a strong correlation between young adults and professionals for the rating of statements within the clusters (r ¼ 0.7, p ¼ 0.017) (Figure 2). Both groups considered work to be most important; information and regulations is the second most important according to professionals and the third most important according to young adults. Both groups also considered hobby to be the least important. The largest difference in rating was found for the cluster social skills, which is prioritised third based on the ratings of professionals and eighth based on the ratings of young adults. For the clusters social skills and computer, independent samples t-tests showed that the mean rating of young adults differs significantly from that of professionals (p ¼ 0.034 and p ¼ 0.038, respectively).

Discussion
In this study, three concept maps were developed detailing the life aspects affected by a visual impairment in young adults aged 18-25 years. The concept maps show that a visual impairment in this life stage influences work, study, social skills and relationships, living independently, computer, mobility and various leisure time activities. Since young adults with a visual impairment are at risk for having an unsuccessful transition, it is important that rehabilitation services consider them as a separate group.
This study shows that the life stage of young adults with visual impairments is most influenced by activities related to study and work. This supports the evidence that study and work are major themes in the lives of young adults with disabilities. [49,50] For example, a study linking the rehabilitation needs of visually impaired young adults to the ICF found that most needs (23.8%) could be linked to the chapter "major life areas" of the activity and participation component; this chapter includes education and work, and most needs prioritised around higher education and options for work. [24] Attending postsecondary education and being employed are considered to be normative social roles by young adults. [51] Moreover, attending postsecondary education is regarded as an investment in future employment and an improvement in potential income, [52,53] whereas other studies show that working results in economic and residential independence. [54] Information and regulations was another cluster considered to be important in the combined concept map. This cluster is related to work and study, since it contains statements regarding successfully following a study, including completing homework and knowing how to use specialised software, and managing things related to study. One statement contains information about laws, regulations and allowances for people with a visual impairment.
Although this cluster has only five statements, the mean importance of this cluster is high. A study on the priority of goals in adults aged 18-55 years also showed that goals related to regulatory and information were in the top 10 priority list based on importance and difficulty. [55] The cluster social skills was also considered important, but mostly among professionals. Training in social skills is considered important for people with a visual impairment, because lacking these skills might affect their ability to succeed in their work and social life. [7,56] However, developing social skills can be challenging, since contextual cues and honest feedback from others might be lacking. Furthermore, sighted people might behave inappropriately, and society as a whole might have a negative attitude towards visual impairments. [57] Recently, internet and technological applications have led to new opportunities and manners for social interaction. [58] Social interaction in online environments does not require interpretation of non-verbal and contextual cues, and visual impairments are less obvious. The popularity of internet and other online applications was apparent in a study among visually impaired adolescents aged 13-17 years, who stated that they had plenty of friends online. [46] A similar result was found by Gold et al., who reported that about 75% of the participants stayed in touch or socialised using online applications; [59] since the opportunities and popularity of social network sites has expanded, [60] these numbers are probably even larger now. Thus, young adults with a visual impairment are probably as likely to socialise online as their sighted peers. Nevertheless, visually impaired young adults experience challenges related to social participation and inclusion in peer groups, building social and intimate relationships, and participation in leisure activities, [13,61] at least in real-life. Social relationships are important in dealing with visual impairment [13] and may be especially important in the transition to adulthood and the related changes that take place.
In this study, the less important clusters were related to sports, activities, mobility, leisure time and hobbies. With respect to sports, activities, leisure time and hobbies, our results support the study of Van Leeuwen et al., in which only 27 rehabilitation needs recorded in patient files (3.6%) could be linked to recreation and leisure in the ICF activity and participation component. However, a discrepancy is seen for mobility, which was rated as not very important in this study, but was a dominant theme in the patient files of visually impaired young adults. [24] Mobility was also important according to two studies evaluating the needs in adolescents aged 13-17 years. [46,62] Studies on the importance of goals in visually impaired adults aged 18-55 years also showed that mobility (outdoors and at home) was considered important, both being in the top 10 priority list. [55] The results of this study thus do not concur with other research, which might be explained by differences in the study population. The studies of Van Leeuwen et al. and Bruijning et al. involved clients seeking rehabilitation services, because they experienced problems in daily life, which probably also relate to mobility, [24,55] whereas our study involved clients already registered at a rehabilitation centre. Therefore, they might already have had mobility training, since this is often one of the first interventions applied after prescription of assistive devices. The studies of Rainey et al. involved children, for who mobility is still a very important topic to address in rehabilitation. [46,62] Visual impairments in young adults mostly emerge at young age. Therefore, mobility is dealt with at a younger age as well, which may explain why mobility seemed less important in this study. Nevertheless, activities related to mobility were still generated in the brainstorm session, indicating the impact of vision loss on this domain; moreover, the mean importance rating was 7.58, which is considered moderately high.
The final stress of the combined concept map was 0.21, and the concept maps of young adults and professionals had a final stress of 0.30 and 0.20, respectively. Meta-analyses across a broad range of concept-mapping studies estimated an average stress value of 0.285, with a standard deviation of 0.04. [63] Thus, 95% of the concept-mapping studies are likely to have a stress between 0.205 and 0.365, with lower stress values suggesting a better overall fit. The concept maps of this study are mostly on the lower side of the range or even lower, indicating that they represent the grouping data well.
Finally, this study demonstrates that professionals tend to ascribe more importance to all clusters of the combined concept map than young adults do, except for the cluster leisure time. However, the correlation between young adults and professionals was high for the importance of individual statements and clusters. Nevertheless, relying solely on the experience of professionals during intake or rehabilitation might lead to a misplaced emphasis on particular life aspects or the use of inappropriate treatment during rehabilitation, not necessarily corresponding to the needs of young adults. [24,47] The results of this study will be used to develop a new, structured intake procedure for young adults. This approach is already implemented for visually impaired adults in Dutch and American rehabilitation practice. [47,64] Such an approach might benefit the rehabilitation process of young adults and, ultimately, increase participation of young adults with a visual impairment.

Strengths and limitations
To our knowledge this is the first study to describe the impact of a visual impairment on all life aspects of young adults (aged 18-25 years) and provide a comprehensive overview of the life aspects affected. Earlier studies focused on specific aspects of life, such as social relations, intimate relations, and study or work. Gaining a fuller understanding of all life aspects affected by a visual impairment is important in order to offer appropriate rehabilitation programmes. Furthermore, greater understanding of all life aspects affected allows to better quantify them in terms of importance to young adult lives, as was done in this study. To accomplish this, a seeding statement was used to generate activities young adults with a visual impairment would like to participate in. The seeding statement was not limited to only those activities impaired by low vision, but was aimed at identifying all activities, in order to generate a broad overview of activities young adults value in their lives. When the seeding statement focused on those activities which are impaired by low vision, too much emphasis would be placed on activities which are severely limited by visual impairment, while it is likely that young adults with a visual impairment encounter limitations to some extent in participation in a broad range of activities. The approach used in this study is comparable to the universal application of the International Classification of Functioning, Disability and Health (ICF), which is also not limited to activities influenced by impairment to identify problems in, for example, participation. [65] A second strength is that the perspective of both young adults and professionals was taken into account. These two perspectives revealed both differences and similarities in ideas towards life aspects and activities that are influenced by having a visual impairment. Professionals rated 29 statements at least 1.0 higher than did the young adults. In particular, five statements were rated significantly higher by professionals than by young adults; these statements concerned driving a scooter, dealing with sexuality or intimacy, finding appropriate software, expectations when being in a relationship, and following the latest fashion trends. This knowledge may increase the awareness of professionals that young adults might have other issues to deal with when they approach a rehabilitation centre.
The individualised method of concept mapping can also be considered a strength. Due to their visual impairment and the logistic difficulties caused by this impairment, it was hardly feasible for young adults to participate in face-to-face brainstorm sessions in a group. These young adults preferred a non-invasive digital approach, which was also more feasible for the professionals. Therefore, it was decided to employ an online conceptmapping procedure, in which professionals individually generated statements by e-mail and young adults generated statements in response to an online questionnaire. Subsequently, participants rated and sorted the statements individually using the online software. Although the online procedure limited group discussion and participant interaction, the use of online brainstorm sessions, and sorting and rating software to increase feasibility and response, has been reported. [30,46,66] Using this personalised, non-invasive digital approach, more clients and professionals were willing to participate in the study (the initial face-to-face group brainstorm session yielded only one participant), thereby providing more generalisable results.
Several limitations also need to be addressed. All young adults were clients of a multidisciplinary rehabilitation centre (MRC) and participated on a voluntary basis in this study, which could have biased the information provided. However, it would be almost impossible to find young adults who are not registered at a MRC, since Dutch health care stipulates that visually impaired people must be informed about the existence of MRCs and their services, which often involves referral to these MRCs. However, this selection process does limit the generalisability of the results.
Another limitation was the low response rate of young adults to participate in the brainstorm of this study, although considered sufficient for concept-mapping. [31] This might have resulted in overlooking information of non-responders, which could be different from the information provided by participants in the brainstorm phase. Furthermore, we did not have any information on visual acuity or diagnosis of participants in this study. Although this can be considered a limitation, concept-mapping is a qualitative research method, thus having a representative sample is often not the aim which is given highest priority. [67] Moreover, a questionnaire will be developed based on the information gathered in this study which will be tested extensively in a large sample of young adults, thereby testing the representativeness of the information provided.
The results of the combined concept map were influenced slightly more by the results of professionals than by those of young adults, because more professionals participated in the sorting (12 professionals vs. 7 young adults) and rating (13 professionals vs. 9 young adults) procedure. Although there is no strict limit on the number of participants involved, it is advised to have 10-20 participants (i.e. a workable number). [31] Despite the tailored methodological approach, response rates among young adults were low. Of the 26 young adults eligible for sorting and rating the statements, only seven sorted the statements and nine rated them. This might have been caused by limitations in the accessibility and user-friendliness of the programmes used. However, the face-to-face brainstorm and concept-mapping workshops initially envisaged yielded only one participant, and young adults stated to prefer a digital approach instead. Furthermore, the response rate is comparable to similar studies, [68,69] and in total 19 participants sorted the statements and 22 participants rated them. These numbers are within or slightly above the recommended number of participants for conceptmapping. [31] Finally, the group of respondents taking part in the brainstorm session, and the sorting and rating of the statements was not always identical. Some participants only responded to the brainstorm question and did not sort or rate the statements, whereas others performed the brainstorm and rated the statements, but without sorting them. Furthermore, five participants were not included in the brainstorm session, but did rate and sort the statements in the subsequent step. However, according to Trochim, it is not necessary that all participants take part in every step of concept-mapping, even though this facilitates understanding of the process. [31] In this study, no participant reported that the procedures were unclear. Furthermore, this approach enabled more people to be involved in this study, which helps to provide a broader understanding.

Conclusions and implications
In conclusion, this study shows that professionals and young adults particularly value activities related to work and study. Furthermore, social skills and (social) relationships are considered important, as are activities of daily living and computer. Less important, but mentioned in the statements, are activities related to sport, hobby, leisure time and mobility. Since young adults with a visual impairment are at risk of an unsuccessful transition, it is important that rehabilitation services consider young adults as a separate group. This study provides a more comprehensive understanding of the life aspects affected by a visual impairment in young adults. Our ongoing research focuses on developing and validating a new questionnaire based on the results of this study, to measure, evaluate and monitor participation needs of visually impaired young adults. This questionnaire may help low vision rehabilitation centres with goal setting and rehabilitation referral of young adults. Ultimately, this might increase the participation of young adults with a visual impairment, a more successful transition to adult life and improvement in their quality of life.