This study investigated the relationship between the onset age of visual impartment and labor market outcomes, including employment, job security, and log monthly wages, among prime-aged adults (those 20–49 years of age) and late-middle-aged adults (those 50–64 years of age). People with adult-onset disabilities showed lower employment rate than those with childhood-onset disabilities, when women had adult-onset disabilities, they were more likely to experience hardness in getting a permanent or temporary job within the prime-aged adults, while persons with adult-onset disabilities were more likely to work for temporary jobs than those with childhood-onset disabilities within the late-middle-aged adults.
The wage-earning employment rates in those with visual impairment were 67.8% among prime-aged adults and 50% among late-middle-aged adults, whereas the corresponding rates in the entire population as of 2015 were 54.9% (73.0% for men and 53.0% for women) among prime-aged adults and 39.1% (70.7% for men and 37.7% for women) among late-middle-aged adults after excluding self-employed and unpaid family workers . The higher employment rate of persons with visual impairment compared to the entire population is likely due to there being a higher portion of men among the visually impaired in the present study than in the general population (68.6% versus 50.4% among adults aged 20–49; 59.8% versus 49.8% among adults aged 50–64) , and it is also caused by the exclusion of the beneficiaries of the National Basic Livelihood Security System (n = 123), which is an income subsidy program, as it is reported that 95% of them are not engaged in work .
However, job security and average monthly wages were lower for those with visual impairments than for the entire population. Among those with visual impairments, 63.9% of prime-aged adults and 40.2% of late-middle-aged adults were permanent employees. These are lower than the corresponding proportion (74.1% among adults aged 20–49; 65.4% among adults aged 50–59) of the entire population . The average monthly wage was 1,774 USD for prime-aged adults and 1,438 USD for late-middle-aged adults, which were lower than the average for wage workers (2,053 USD) for the entire population above 15 years of age .
Our study showed that the employment rate was lower for those with adult-onset disabilities among prime-aged adults, especially when a person experienced onset of visual impairment over the age of 25 years old. If a person experienced visual impairment in the middle of their lifespan, they might find it difficult to continue working, maintain the same level of job performance, or obtain new job opportunities . In contrast, those with childhood-onset disabilities have relatively diverse opportunities to acquire skills required in the job market, such as digital skills and social skills . Persons with adult-onset disabilities might need time to accept their disability , and the delayed time for recovering their functional limitations and social relationship would hold back their employment. It is known that people with higher levels of disability acceptance are more likely to want to participate in the labor market and have a higher employment rate or re-employment rate [33,34,35], therefore, support for psychological recovery can be helpful . In addition, those with adult-onset disabilities face a lack of adequate rehabilitation programs for returning to work or getting a decent job , and they do not have many job choices other than massage-related work or simple labor jobs . As there is a growing demand for skill trainings to reflect the rapidly changing occupations and a variety of job types, policy efforts are needed to develop vocational rehabilitation programs, including recent job trends, professional career counseling and job match, group counseling services or individual case management . These efforts may have effect on satisfying the demands of job seekers who want to work in occupations other than massage-related work .
We also demonstrated that the disability severity was significantly associated with the likelihood of permanent employment. Both prime-aged adults and late-middle-aged adults with severe visual impairment had a lower likelihood of having a permanent job. It is known that the employment rate of the severely disabled group in persons with visual impairment is much lower , and our result proved that the gap came from permanent employment. Some employers prefer hiring people with mild disabilities because those with severe disabilities need assistive devices or personal support , and it may create a barrier when those with severe disabilities try to find an adequate workplace . Even if a severely visually impaired person finds a job, some of them are assigned inappropriate tasks due to a company does not carefully consider their characteristics or prepare the assistive devices. In addition, the unmatched tasks with their ability threatens their work-related identity, and the loss of the identity can be linked to quit a job . Under the current Mandatory Employment Quota system, double rate is applied for the severely disabled, when the mandatory employment rate for the disabled is calculated, since 2010 . However, additional policy for support the retention of employment rate is also important, through wages, appropriate work arrangements, installation of convenience facilities, and personal assistance .
Education level are known human capital factors of economic independence , and their effect was only significant in permanent employment among prime-aged adults. However, the education effect was opposite for temporary employment, especially among the late-middle-aged adults. The likelihood of temporary employment became significantly lower for the college or higher education group, which suggests that their preexisting knowledge or skills would not be adequately utilized and the job quality would not be suitable for this group. Part-time jobs can be a complementary means for people with visual impairment, especially who have received a high level of education but working hours are limited due to health reasons or other priorities in their lifecycle, providing opportunities for economic independence and broad social participation [43, 44].
When the onset age of disability was 25 years or older, the monthly wage level for permanent workers was higher, although the odds of permanent employment were lower. It is possible to continue to work even after occurrence of adult-onset disabilities, if job security is guaranteed  and wages can increase over time . The lower income level of people with childhood-onset disabilities may be caused by low job quality . Young persons with visual impairment often face challenges in mobility and interpersonal relationships, and their working environment may not be disability-friendly . Our analyses also showed that those with a disability onset age of over 25 years old showed higher levels of job satisfaction (88.5%) than those with a disability onset age of under 6 years old (85.2%), 6–17 years old (81.3%), or 18–24 years old (71.4%) among permanent employees aged 20–49 (Table S3 in the supplementary material).
The subgroup analysis by sex showed that women experienced a lower employment rate when their onset age of disability was over 25 for both permanent and temporary jobs, whereas men had difficulties only in permanent jobs. Women with disabilities have more socio-economically disadvantages than men , and the present study emphasized that adult-onset disabilities can be an additional barrier for women, even after adjusting for marital status or educational level. Women’s jobs are less likely to be stable, making it difficult for them to return to work. Women might also face negative employer attitudes when trying to obtain a job after visual impairment. They may face even more obstacles if they have children under the age of 16 . These imply that job flexibility, e.g. time-selective jobs, and vocational training programs to improve their work capabilities rather than simple tasks are needed for women with adult-onset visual impairment [44, 49].
“Aging with disability” and “disability with aging” are mixed in late-middle-aged adults aged 50–64. Many people in this age group retire early from their original work or transition to other jobs . According to our study, the odds of employment were higher when the onset age of disability was 25 years or older, especially for temporary employment. Temporary jobs that do not require specialized knowledge or skills may be easy to find for those with adult-onset disabilities.
The effect of the onset age of disability on wages was reversed for permanent workers and temporary workers within late-middle-aged adults. The higher the onset age of disability, the lower the wages in permanent workers, whereas the opposite was true in temporary workers. Permanent jobs tend to provide more flexible working conditions, allowing employees with adult-onset disabilities to adjust their working conditions without fear of losing their jobs. Alternatively, those with adult-onset disabilities in permanent jobs are likely in managerial positions, where they have self-determination on their working conditions and are able to reduce their working time, work intensity, and salary. In the case of temporary jobs, those with adult-onset disabilities would participate in non-skillful work or manual labor, spend long hours at work, and earn relatively higher wages. On the other hands, individuals with childhood-onset disabilities may also have experienced pre-labor market differences when the late-middle-aged adults were being educated in the 1960s–70 s . There has been social prejudice against those with disabilities , so persons with childhood-onset disabilities would have had difficulties in accumulating labor skills or qualifications while growing up. This, in turn, could lower their employment rate and wages.
Job training was found to increase the likelihood of temporary employment in late-middle-aged adults. Approximately 8% of those aged 15 years or older in the entire population had job training experience , while 11.8% of prime-aged adults with visual impairment and less than 5% of late-middle-aged adults with visual impairment had such training. Job training programs are not specialized enough for those with visual impairments, which may restrict these persons to assembly work or massage acupressure training, regardless of education status . Further studies need to assess the role of job training or occupational rehabilitation programs in those with visual impairment, considering the effect of onset age of disability and the severity of the disability.
There are several limitations to this study. First, people with mild disabilities accounted for approximately 70% of the study sample. This study therefore does not appropriately represent people with severe visual impairment, such as blindness. It may also underestimate the effect of onset age of visual impairment on labor market outcomes. In addition, although we used a representative national survey data of individuals with disabilities, the final sample size was not enough to generalize for those with visual impairment. Further studies need to reflect the situations of severe visual impairment using the revised disability severity index of the Korean Disability Registration system  and a bigger size survey or cohort study for examining the labor market of individuals with visual impairment would be needed. Second, job quality was not fully considered, as this study only considered employment and income security. Further research should consider job quality, such as development possibilities, work conditions, relationships, and employers’ understanding of disability .